We had our new house painted with Dunn Edwards Acri-flat “Loam” (dark brown) color in 1997. It was primed before painting. We used Hardiplank cement fiberboard siding and have wood trim.
After about a year, the paint has taken on a yellowish tinge anywhere it’s had sun exposure (which is most of the house). The more time passes, the worse it gets. It doesn’t come off on your hands and doesn’t wash off. We’ve repainted the wood trim several times with the same kind of paint and it also develops a yellow tinge after a time.
I looked on the internet and saw that problems like efflorescence and alkali can occur on masonry surfaces, but we also have this problem on the wood surfaces where the sun shines.
I’ve called the company and they are sending out a salesperson to look it over. Any ideas on what might be going on here?
Thanks from a newby and a neophyte in all construction related things.
Calico
Edited 9/23/2004 11:44 am ET by Calico
Replies
Wonder if there's somekind of interaction with the primer? Otherwise sounds like a classic symptom of exposure to UV from the sunlight. If so I imagine the only cure is repainting...
is the wood cedar? what was it primed with?
Was the Hardiplank PrimePlus or did the painter prime it? Did he use masonry primer on the siding?
What was the weather like when painted? And how much time elapsed between prime and topcoat?
Something could be bleeding through and needs to be sealed.
Is "Loam" a factory color or was it mixed at the store? If mixed at the store, did they use the right base color?
or you could have gotten a bad batch of paint..it happens
Edited 9/23/2004 1:16 pm ET by Barry E
latex or oil based?
Oil can be more prone to yellowing from UV.
For clarification...is the yellowing occuring on both the wood trim and the hardiplank, or just the wood trim?
"Dunn Edwards Acri-flat" ..would be acrylic
Barry E-Remodeler
Time for reading glasses. I firsst read it as "Accu-flat".
Doh!
There was a thread about glasses.
But maybe you didn't see it!
;)
My FIL keeps complaining about his glasses. He says the hinge screw works loose, so he takes them off to tighten the screw.
But once he has them in his hand instead of on his nose, he can't see the screw to fit the baby screwdriver into it, LOL
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Too funny. Before my wife had lasik, she had far vision of 20/400 and 20/800. And here I am whining about near vision of 20/25 and 20/33. Time out, I gotta go change my diaper.
Fortunately my far is still good, 20/13 and 20/15. I do have a pair of cheaters for reading. Not quite used to them, though.
Getting old is becoming a contact sport for me. It hurts!
I've got bifocals now. Sometimes it still doesn't help. <g>
Barry E-Remodeler
The thing that kills me is the labels on the shelves at HD. Too close for my far vision, too far for my near vision, and too blamed small period!
All paints are subject to sun damage. The sun causes the binders to break down and the pigments to bleach out. A "well-designed" paint will have the two processes occur pretty much in sync, so as the pigments bleach out the binders holding them break down and a fresh surface is exposed.
It sounds like the paint you have has binders that are "too strong" in relation to the pigments, so you're seeing a layer of bleached-out pigments on top of the original color.
It could be the pigments in the paint are bleaching due to the exposure. Im not sure what color Loam looks like but some color's pigments are prone to UV breakdown and they might have used interior pigments when they should have used exterior Pigments.
Welcome to Breaktime Calico. I'm not familiar with the brand of paint you used but if you have had to repaint since 97, I would change brands. Dark colors particularly when exposed to the sun will fade or discolor. Some manufacturers are better with the dark colors than others. Flat acrylic should not yellow like an oil. From the maintenance perspective, I would not use flat dark brown on large areas. My best luck has been with either California Premium House and Trim, satin gloss acrylic or Cabots problem solver. It's always best to contact the siding manufacturer and use their recommendations, the same with paint. I use all one brand and follow the label directions. Some paints are just better than others.
Beat it to fit / Paint it to match
Thanks, Everybody, we're in the mountains (Sierras), and the dark brown just seemed to blend into the scenery. It's kind of a "National Park Building" brown. I'd really hate to change paint colors, but I hear what you're saying about dark colors and UV light. How often you suppose the national parks repaint their buildings?
The Dunn Edwards color "Loam" is a custom color and had to be mixed at the store, at least that's what I get out of looking at the paint can. Says it was custom and couldn't be returned.
The paint is acrylic.
I don't know what kind of primer was used on the Hardiplank. I feel pretty confident it wasn't pre-primed, and am not even sure Hardy was making pre-primed Hardiplank then.
I saved all my e-mail communication with the contractor, and from what I can tell, the garage was painted in 12/96 and the house painted in 2/97. Both the garage and the house are having the problem.
I don't know how long they waited between putting on the primer and painting.
I'd thought about the problem having something to do with the pigments in the paint. I know nothing about colors, but did look around the internet some, and brown has more yellow in it than anything else. And that's the color that's "surfacing" on the brown paint. It almost looks like someone took a VERY pale piece of chalk with a yellowish tinge and smeared it across the siding. It doesn't come off on my hands, though, when I rub them across the siding.
The discoloration is happening on both the Hardiplank and the wood trim, but only if it's in the sun. For example, we have a screened in porch that gets no sun, and there's no problem with the paint there.
I'm not sure what kind of wood the trim is.
I went to the James Hardy web site (they make the siding we used), and they show that Dunn Edwards recommends the Acri-flat as one of the paints that can be used on their siding.
I got a call from the district manager of Dunn Edwards and they're having a salesperson come up and look at it. We'll see what happens with the company.
Thanks again for your insight,
Calico
Edited 9/24/2004 8:02 am ET by Calico
Edited 9/24/2004 8:19 am ET by Calico
Edited 9/24/2004 8:22 am ET by Calico
Edited 9/24/2004 8:24 am ET by Calico
Most exterior paints contain approx. 30 different ingredients. One of those is a UV inhibitor. Sounds like this company sells its product without regional adjustments to the formula to compensate for differing exposures. One size fits all approach.
All you might need is more UV inhibitor in the product. Or maybe you need a different company's product that does/will put in more UV inhibitor.
And.....they may not be using the most fade resistant pigments either.
Knowledge is power, but only if applied in a timely fashion.
Edited 9/24/2004 10:16 am ET by GOLDHILLER
Have you tried contacting the paint manufacture?
Yes, I've called the manufacturer and talked to the district manager. He's sending a salesman to take a look at it by the end of next week. We'll see what happens.
Calico
Goldhiller may be onto something there.
In the higher elevations you are subject to a lot more UV radiation than most folks. That could be reducing the effects of the reds in the mix, allowing the yellows to become stronger.
our PAINTERS AROUND HERE HATE HATE HATE THE DARL BROWN COLOURS.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Well……. I guess this is as good of an opportunity to drop a little paint info onto the forum as any other.
Following is a post from a colleague on another forum. This guy knows paint and shared all this with us some time back. Gave me permission to post it wherever I see fit. So here it is.
I'll break this into several posts cause there's just a ton of stuff here.
Paint 101 - Nestor Kelebay
All paints, whether latexes, oil based paints, polyurethane fortified alkyds, epoxy paints or artist's paints all consist of 4 separate
components:
1.) the binder - this is the stuff that forms the continuous film over the surface. It's job is to dry to a clear or transluscent
continuous film which sticks well to the substrate but does not remain tacky after drying and protects the substrate from sun,
rain, UV light, dirt, etc. Latex paints use extremely tiny pieces of plastic as a binder. In latex paints,the plastic is made out of
polyvinyl acetate (which you probably know better as "white wood glue"), polymethyl methacrylate (which you probably know
better as "plexiglass") or a styrenated acrylic plastic (which I don't know the macro equivalent of). Very few paints use
styrenated acrylic plastic for the binder.
Those latex paints that use polyvinyl acetate plastic as the binder are called "PVA" or "vinyl acrylic" paints, whereas those that
use plexiglas are referred to in the industry as "PMMA" or "100% Acrylic" paints.
Basically, PMMA are better in every category than PVA paints except cost. PMMA dries to a harder film, is more UV, alkali,
acid and moisture resistant, it sticks better to most substrates and it's adhesion isn't as adversely affected by moisture in the
substrate. PVA resins are used primarily for inexpensive paints and latex primers where good moisture, UV resistance and
hardness are not as important to have.
Oil based paints no longer use drying oils like boiled linseed oil as the binder. Nowadays, essentially ALL of the "oil based
paint" you buy uses alkyd resins as the binder. The polyurethane "varnish" that you buy in the paint store is actually a modified
alkyd resin. Really, the only difference between oil based wall and floor paints and alkyd and polyurethane "varnishes" (and
polyurethane hardwood floor finishes) is that the paints contain pigments to give them color and opacity whereas the clear coats
don't. Also, the clear coats will use more expensive alkyd and polyurethane resins that dry to a clearer (more transparent) film
to better display the wood substrate. Much more on the chemistry of drying oils, alkyds and polyurethanes later on in this post.
2.) the pigments - The difference between a dye and a pigment is that dyes are colored molecules that are normally dissolved in
alcohol or mineral spirits whereas pigments are tiny solid colored particles that are vastly larger than dye molecules. Wood
stains use dyes, paints ONLY use pigments. When the pigment is suspended in glycerine so that it can be more accurately
dispensed for tinting purposes, it is refered to as a "colorant".
Not to put too fine a point on it, but an "alcohol" is anything with a hydroxyl group bonded to a carbon atom C-OH, and
glycerine has three of those, so glycerine should actually be correctly called "glycerol". They use glycerine as the carrier fluid for all the paint colorants in the paint tinting machine because glycerine is soluble in both mineral spirits and water, so the same
tinting machine can be used to tint both oil based and latex paints without changing the colorants in the machine. Glycerine is an
alcohol and all the glycerine added when tinting the paint evaporates out of the paint as it dries. But, because glycerine
evaporates much slower than water, it can take a month for all the glycerine added when tinting to evaporate from a paint film.
Basically, paint pigments can be subdivided into two types; organic and inorganic. (And, you can also subdivide each of these
into "natural" and "synthetic" depending on whether they're produced in nature or in a chemistry lab.)
The organic pigments are the ones you normally associate with the primary and secondary colorwheel colors, like red, yellow,
blue, green, orange, purple and magenta. The inorganic pigments are the ones you normally associate with "earth tones", like
white, black, mustard yellow, reddish brown, chocolate brown and a very dark brown called "Raw Umber".
For the purposes of understanding the properties of paint pigments, it's best to think of all the organic pigments (red, blue,
yellow, etc.) as synthetic and all inorganic pigments (earth tones) to be natural.
Now, all of the inorganic pigments you find in colorants in the paint tinting machine (black, white, mustard yellow, reddish
brown, chocolate brown and dark brown) are all the synthetic equivalents of naturally occuring colored rocks found in various
places on this earth. For example, the artist's pigment "Raw Sienna" gets it's name from the Italian town of Sienna where the
rocks are a mustard yellow in color. Artists have been collecting these rocks for millenia to grind up into a fine powder and use
to color their paints. And, basically, if you think of these inorganic pigments to be nothing more than finely crushed rocks, you
don't have to remember their properties because they're easy to figure out. First off, for a rock to be 300 million years old, it
has to be very chemically stable, or it would have disintegrated on it's own by now. If you grind up a 300 million year old rock,
the colored dust you get is 300 million years old too, and equally chemically stable.
It's that chemical stability that gives rise to the excellent colorfastness and resistance to fading from UV light from the Sun that is characteristic of ALL inorganic pigments.
Also, rocks are pretty darn good at being opaque. In fact those rocks that are transluscent or transparent are generally highly
valued as gem stones. If you grind up an opaque rock, the dust you get is equally opaque, and it's this high degree of opacity
that gives rise to the very good hiding ability that is also characteristic of all inorganic pigments. So, if you pick paint colors that call primarily for the following colorants in their tint formula:
titanium white - which is white as Manitoba snow
carbon black - which is soot actually (yes, really)
yellow oxide - which is mustard yellow in color and is a form of iron oxide
red oxide - which is rust (reddish brown) in color and is the most common form of iron oxide
brown oxide - which is chocolate brown in color and is also a form of iron oxide, and raw umber - which is very dark brown in color and is yet another form of iron oxide... then what you're spreading on your wall will essentially be finely crushed rock that has both the high opacity (high hide) and chemical stability (excellent colorfastness) that we take for granted in rocks.
By contrast, the organic pigments like (red, yellow, blue, green, etc.) are all over the map when it comes to opacity and
colorfastness. Some of these (notably Hansa yellow and Napthol red) look like pieces of yellow colored glass under a
microscope, and that results in their having poor hiding ability. Other pigments, like Toluene red, have very poor UV resistance,
and that results in low colorfastness and the associated problem of having to repaint an entire wall to repair a nail hole cuz the
paint on the wall has faded from it's original vibrant color. When it comes to colorfastness and hide, none of the organic
pigments are as good as any of the inorganic pigments.
Pigments are suspended in a paint film much the same way raisins are suspended in raisin bread. Their job is to color the film,
hide the color of the substrate, and to lower the gloss level of the film from high gloss down to flat depending on the amount and
size of the pigments added.
3.) Additives - A typical gallon of latex paint will contain over 30 different additives. These include coalescing solvents to help
the acrylic resins coalesce as the paint dries, rheology modifiers to thicken the paint when it stops flowing so that it won't sag on
vertical surfaces, glycols to prevent it from freezing in subzero temperatures, mildewcides, corrosion inhibitors, wetting agents,
antifoaming agents, UV protectants, etc.
4.) The solvent - who's job is primarily to thin the paint. This reduces the viscosity of the paint sufficiently that it can be spread
with a brush and remain inviscous enough so that surface tension can straigten out any unevenness in it's surface (like brush
strokes) before enough of the solvent evaporates that the paint becomes to viscous to self level.
Except for true drying oil based paints that are thinned with turpentine, all of the solvent added to thin latex, alkyd and
polyurethane paint will evaporate from the paint as it dries.
In the case of latex paints, water is not correctly called a "solvent" even though it does exactly the same job as "paint thinner" in alkyd and polyurethane paints.
Knowledge is power, but only if applied in a timely fashion.
FILM FORMATION
How do latex paints form films?
Latex paints consist of tiny PVA or PMMA plastic particles (called "resins") and colored particles (called "pigments")
suspended in solution of water and a water soluble solvent called a "coalescing agent" as a slurry (solid particles suspended in a
liquid).
When this slurry is spread over a surface, first the water evaporates, leaving the plastic resins surrounded by the more slowly
evaporating coalescing solvent at ever increasing concentration. The coalescing solvents "soften" (pronounced "dissolve, kinda")
these acrylic resins sufficiently (and make their surfaces so mushy) that the forces of capillary pressure and surface tension that
exist between any two resins can deform the resins and cause them to all pull on each other until any gaps between resins are
eliminated and the paint film consists of solid plastic film. These coalescing solvents then evaporate from the paint giving the
room that "freshly painted smell". Once you smell the coalescing solvents in the air, you know that film formation of the paint is
nearing completion and the paint film is rapid becoming harder and harder as the residual coalescing solvent remaining inside the
paint film evaporate from it.
Thereafter (for regular latex paints) the only thing that's going to happen inside the paint is evaporation of the glycerine added
when tinting the paint. However, if this is a latex floor paint or a top quality latex wall paint, it will most likely use a "crosslinking"
acrylic resin as the binder. These crosslinking acrylic resins form chemical bonds with their neighbors, causing all the resins to
bond chemically to one another over the next month or so, resulting in a considerably harder paint film than non-crosslinking
latex paints produce.
How do drying oils form films?
The binder that forms the film in true "drying oil" based paints is most commonly boiled linseed oil. Drying oil finishes like Danish
oil and Swedish oil will most commonly use Tung oil as the binder because it dries harder, clearer and yellows less than linseed
oil. Basically, the primary difference between Tung oil and Danish and Swedish oil is that the Danish and Swedish oil will have
hunks of dried plant sap called "copals") dissolved in the oil to increase the hardness of the film. "Amber" is a very expensive
copal that's used as a gem stone (even though it's dried sap) in making jewelry. Very expensive varnishes used on musical
instruments (notably violins) will be made by dissolving real amber in a drying oil (like linseed oil, Tung oil, Safflower oil, oiticia
oil, Tall oil, poppy seed oil, walnut oil and others). (I don't know which of these drying oils forms the hardest clearest film, but
my guess would be Tung oil since it's the only one that's still commonly used in oil based wood finishes.)
All plant oils and animal fats and oils (like whale oil) are "triglycerides". That means they consist of three long hydrocarbon
chains (called "lipids" or "fatty acids") connected to a central glycerine molecule. Each of those three fatty acids in the oil
basically consists of a backbone of carbon atoms with two hydrogens bonded to each carbon atom. However, all plant oils
(and I think animal fats, too) will occasionally have instances in those fatty acid carbon chains where two neighboring carbon
atoms only have ONE hydrogen atom bonded to each of those carbon atoms, and a double bond between the carbon atoms.
Like this: -HC=CH-
Those such instances are called "unsaturated sites", and they're the reason why drying oils will dry from a liquid to a solid when
exposed to oxygen. When an oxygen molecule in the air happens to come between two unsaturated sites in close proximity,
three things will happen:
1. the double carbon=carbon bonds in both unsaturated sites will break
2. the oxygen molecule will dissociate into two oxygen atoms, and
3. a PAIR of C-O-C "crosslinks" will form between those two unsaturated sites.
The two unsaturated sites don't have to be on the same oil molecule, they can also be on neighboring oil molecules. As oxygen
in the air converts more and more pairs of nearby unsaturated sites into pairs of C-O-C crosslinks, the oil molecules become
ever increasingly "spot welded" together, and this "auto-oxidation" process is the mechanism by which a liquid drying oil
gradually dries into a solid film when exposed to the oxygen in the air.
YELLOWING in oil finishes is actually caused by auto-oxidation occuring at a single unsaturated site. What happens is that
-HC=CH- becomes -HC-(C-O-O-H)- and that -O-O-H group (called a "peroxide" group) is what causes the yellowing.
Peroxides are inherantly unstable, and exposing yellowed oil based paint to UV light from the Sun will break those peroxide
groups down, releasing oxygen molecules from the paint and eliminating the yellowing of the paint at the same time.
Since crosslinking only occurs where you have two unsaturated sites in close proximity, oils with more of those unsaturated
sites in their fatty acids dry into a harder film faster than oils with fewer of them. Most vegetable oils are non-drying (like
coconut oil) or semi drying (like soy bean oil), and only a dozen or so oils will actually dry into a solid (most notably linseed and
Tung oil). Crude oil (petroleum) consists of hydrocarbon molecules with NO unsaturated sites. Crude oil will never dry into a
solid or even become any more viscous due to exposure to air. If it gets any more viscous, it's entirely due to evaporation of the
shorter hydrocarbon molecules from that crude oil.
So, in a nutshell, when you paint with a real "oil based" paint, the first thing that happens is that the paint thinner evaporates, and
you're left with a film of linseed oil molecules spread over the substrate. Oxygen from the air then crosslinks those linseed oil
molecules together to form a solid film over the substrate.
(People often presume that oil based paint dries slower than latex paint. That's due to their misunderstanding of the film
formation process. The turpentine in oil based paint dries FASTER than the water in latex paints, but that auto-oxidation
process whereby the oil film subsequently transforms into a solid is much slower than the coalescence that takes place in latex
paints.
Knowledge is power, but only if applied in a timely fashion.
What's an alkyd resin?
The name "alkyd" actually comes from the words "alcohol" and "acid", which combined give you al-cid, which people decided
should be pronounced "alkid".
From the prior discussion of drying oils, we know that it's the unsaturated sites (-HC=CH-) on the three fatty acid hydrocarbon
chains of plant oil molecules that causes those oils to dry into a solid.
Common sense tells us that the more of those unsaturated sites there are on the fatty acids hydrocarbon chains of the oil, the
faster that oil will dry into a solid, and the harder that solid will be. That's because the more C-O-C crosslinks created, the
more each oil molecule will be constrained from moving independantly of the other oil molecules. If no oil molecule can move
without all of it's neighbors moving too, then movement becomes more and more difficult, and the oil becomes a harder and
harder solid.
To make an alkyd, what we do is take those tryglycide oil molecules apart to make three fatty acid chains and a glycerine
molecule out of each oil molecule. We then cook up a bunch of those fatty acid chains in a pot with hydrogen peroxide
(H-O-O-H). Hydrogen peroxide is inherantly unstable, and at the cooking temperature it breaks down into a water (H2O)
molecule and an Oxygen atom.
Now, how can I put this politely? Lone oxygen atoms are basically the horny drunken sailors of the chemical world. They'll
"react" with whom/whatever they can as soon as they can, and it's that aggressive reaction of lone oxygen atoms with dyes and
chemicals that makes bleach and ozone machines possible. Both rely on the lone oxygen atoms produced from sodium
hypochlorite (NaOCl) breaking down into salt (NaCl) or ozone (O3) breaking down into oxygen (O2) to produce lone oxygen
atoms that then react with dye molecules or other molecules to break them into pieces. Once broken up into pieces, no
individual piece of the former dye molecule will absorb certain frequencies of light like the original dye molecule did. Similarily, if
a molecule in the air smells, and you break it into pieces, you won't smell anything since no individual piece will affect the
sensors in your nose the same way.
Now, when the hydrogen peroxide in the pot breaks down at cooking temperatures, the lone Oxygen atom produced reacts
with the hydrocarbon chains of the fatty acid to form those all important unsaturated sites. That is, each lone oxygen atome will
convert this:
-HCH-HCH-HCH-HCH-
into this:
-HCH-HC=CH-HCH- and a H2O molecule (which turns into a butterfly and flies away).
Eureka! We now have an unsaturated site on that fatty acid.
And, since we can make great gobs of those unsaturated sites with hydrogen peroxide, we don't need to start with an
expensive oil like linseed oil that has a lot of them to begin with. Instead, we can start with a cheap plentiful oil (like soy bean
oil), break it apart into fatty acids and glycerine molecules, and then cook those soy bean fatty acids in a pot with hydrogen
peroxide to make "souped up" fatty acids that have unsaturated sites all over them like ugly on a frog.
Once we have those souped up fatty acids, we then mix them in a pot with glycerine and a "dibasic acid" like phthalic
anhydride, stir and simmer.
("Phthalic" is actually short for "Napthalic", and the word "anhydride" means "without water". So, phthalic anhydride is what you
had before you added water to make napthalic acid. Kool-Aid crystals can be though of as "Kool-Aid anhydride".)
Now, each of those three things (the phthalic anhydride, the glycerine and the souped up fatty acids) will react with the other
two. And, so what happens in our cooking pot is that "clumps" of souped up fatty acids are formed, and these clumps of
souped up fatty acids are what we call "alkyd resins".
When we dissolve these alkyd resins in mineral spirits, we have a tint base for an "alkyd paint". Now, if we spread that solution
of alkyd resins dissolved in mineral spirits over a substrate, the first thing that happens is that the mineral spirits evaporate.
Those clumps of souped up fatty acids then come into closer contact, and there's pairs of unsaturated sites in close proximity to
each other all over the place. The oxygen from the air then crosslinks all those nearby pairs of unsaturated sites together to form
C-O-C crosslinks fast and furious.
And, it's really the fact that alkyd resins have so many more of those unsaturated sites that causes them to dry to a harder film
faster than the old boiled linseed oil based paints. With the old true drying oil based paints, it literally took 2 or 3 days for the
paint to dry. Nowadays, alkyd paints are dry to the touch in an hour or two. And, the increased number of crosslinks that form
has a comensurate effect on hardness too; alkyd paints dry to a harder film faster than the old drying oil based paints ever did.
This crosslinking by oxygen continues at a perpetually slower rate all the time the fatty acids are exposed to air. Consequently,
both drying oil and alkyd coatings (and even window putty which is a mixture of clay and linseed oil) gradually get harder and
more brittle with time. But, it's alkyd paints that form the hardest, brittlest films, and it's that inability of the alkyd film to stretch
as wood swells and shrinks with seasonal changes in humidity that limits the lifespan of alkyd paints on wood outdoors.
When you make alkyd resins, the ratio of the amount of oil you use to phthalic anhydride is known loosely as the "oil length".
"Long oil" resins use more oil and less phthalic anhydride, and dry to softer films that are more suitable for use over wood
outdoors as exterior alkyd paint for example. Short oil alkyd resins use less oil and more phthalic anhydride, and dry to harder
films more suitable for alkyd floor paints (which have to be hard to resist dirt becoming embedded in them underfoot). If you
make a "zero oil length" alkyd resin by combining phthalic anhydride with glycerine, what you actually have is a polyester resin.
These polyester resins are what most "powder coatings" are made from.
We often call these powder coatings (like the ones on steel bathtubs, the coating on the inside of a hot water heater, the hard
coating on your stove's cooktop) by the term "enamel" or "baked on enamel". That phrase "baked on enamel" means that the
way you apply the coating is by putting a mixture of polyester resin powder and colored pigments on the substrate, and then
baking the whole business for 10 or 20 minutes at 350 deg. F. until the polyester resins melt and fuse together, trapping the
colored pigments inside the continuous polyester plastic film. When cool, such powder coatings typically have about three times
the hardness and durability of alkyd paints. The blue/grey coating on the inside of your oven is a special kind of powder coating
called a "ceramic coating", which is baked at about 1300 deg. F.
Knowledge is power, but only if applied in a timely fashion.
So, what's a "polyurethane"?
Polyurethane paints and "varnishes" are really just alkyds on steroids. Recall that most alkyds are made by combining phthalic
anhydride, glycerine and souped up fatty acids.
To make a "polyurethane resin" you just add a chemical called a "di-isocyanate" to the pot. BUT WHAT THE HECK IS A
DI-ISOCYANATE? An isocyanate is anything that has an isocyanate group in it, and an isocyanate group looks like this:
-N=C=O
The most commonly used di-isocyanate is toluene di-isocyanate.
NOW, when an isocyanate group (-N=C=O) meets a hydroxyl group (-OH), you get a "urethane" group, and it goes
something like this:
A-N=C=O + HO-B = A-(NH)-(C=O)-O-B
and that ugly -(NH)-(C=O)-O- thing in the middle is a "urethane" group.
Urethane linkages are pretty strong (I don't know why), so when they form WITHIN alkyd resins you effectively get alkyd
resins that are internally cross braced with strong urethane groups, and this makes the alkyd resin harder (if you could squeeze
one) and stronger (if you could stretch one) much like the roll cage in a race car makes it stronger in a crash. As a result,
polyurethane "varnish" is really just unpigmented alkyd paint made out of "stiffer" alkyd resins.
The important thing to note is that polyurethanes, alkyds and drying oils all rely on exactly the same film formation mechanism.
That is, the reaction of O2 molecules at places where two unsaturated sites are in close proximity to form C-O-C crosslinks
that "spot weld" the fatty acids together at those places. Also, since O2 from the air will also react at a single unsaturated site to
form a -HC-(COOH)- peroxide, drying oils, alkyds and alkyd based polyurethanes all yellow with age. And, since the
peroxides that formed in each are all equally unstable, you can eliminate that yellowing in drying oil, alkyd and polyurethane
coatings by exposing them to strong UV rays (like those in sunlight). Also, just as with alkyds, you can make "long oil" and
"short oil" polyurethane resins that will form harder and softer films, too. Finally, since it's the crosslinking of the souped up fatty
acids in alkyd and polyurethane resins that causes the film to solidify, polyurethane based paints, "varnishes" and hardwood
floor finishes have much the same drying time as alkyd paints.
The word "enamel" only has a clearly defined meaning in the field of dentistry. As it applies to paints, the origins of the word
"enamel" are unknown, but most people believe the word originated when someone put a can of real varnish (made by
dissolving dried tree sap called "copals" in boiled linseed oil) in a paint tinting machine to make a "paint" that would dry to a
harder film than an ordinary linseed oil based paint would. As a result, the commonly understood meaning of the word "enamel"
has become well settled, and it now means "a paint that dries harder than you'd otherwise expect". However, as a result of
ongoing improvements in the resins used in making latex and "oil based" paints, EVERY paint nowadays dries to a harder film
than the corresponding paint produced 10, 20 and 30 years ago did.
Consequently, some opportunistic paint companies have taken to slapping that word "enamel" on every can of paint they make
save for their flat latex paints (which is the softest paint they make). So, when you see the word "enamel" on every can of paint
a company makes, the meaning of the word changes from "this paint dries harder than you'd expect" to "Hey you! Yeah you.
Buy this paint!" That is, paint companies are exploiting the fact that most people are paint-illiterate to try to dupe them into
buying their paint. Since people generally believe an "enamel" dries to a harder film than an ordinary paint would, for the same
price, most people would presume the "enamel" would be the better value.
Actually, since the first enamels were probably just pigmented varnishes, and polyurethane has effectively replaced varnish as
the clear coat of choice over wood indoors, the most correct definition of an "enamel" nowadays would be a polyurethane
based paint!
---------------
PMMA is about twice as expensive as PVA, but it makes for paint that sticks better to damp surfaces, doesn't
soften up as much if it gets wet, sticks to most surfaces better, is more UV, acid, mildew and alkali resistant,
doesn't remain slightly sticky after it dries and forms a harder film. It simply makes for a better paint in any
category you can think of that's important in a good paint, except price.
Secondly, the most important pigment used in paints is arguably the white pigment titanium dioxide. Titanium
dioxide is relatively expensive compared to other white powders such as talc (magnesium silicate) or chaulk
(calcium carbonate) or clays (like Kaolin clay). But, titanium dioxide his a very high refractive index (second only
to diamond) and that means it bends light through a much greater angle than talc or chaulk (or zinc oxide).
That's super important in promoting high hide because the paint film is very thin. Consequently, the more you
bend incident light, the further it travels laterally in the shallow paint film and the greater the liklihood of it being
absorbed before it hits the substrate and is reflected back. Also, by having a higher refractive index, the fewer
the number of refractions you need to total 180 degrees and send the light back where it came from without it
hiting the substrate at all. That's important because if it hits a colored substrate, then some of the incident light
will be absorbed and the color of the light reflected from the substrate is what gives you "poor hide".
No one is going to give you titanium dioxide for the price of talc or chaulk, so with white paints, the more they
cost the higher the liklihood that you're paying for more titanium dioxide, which will give you better hide.
You see, the whole problem with paint is that it's a techical field where you have to know what in the paint does
what to know if you need to pay more for it or not, and that just doesn't lend itself well to easy understanding by
the general public.
The problem is that some times cost IS important (as in the case of white and off-white paints), and other times
it really isn't (as in the case of interior heavily pigmented paints like Navy Blue or Blood Red). It's just not ####subject that you can reduce to a few simple rules except:
1. The more you pay, generally the better the paint you get, and
2. You don't always need the extra quality you may be paying for. Ceiling paints are simply not as good as wall
paints for scrubbing because more of their cost goes into buying better additives so they don't spatter instead
of harder drying resins so they stand up to scrubbing better.
3. Buying a paint that's meant for the purpose is ALWAYS going to yield better results than buying according to
brand loyalty. If you're painting a floor, buy a FLOOR paint, not a wall paint regardless of who's name is on the
can. Ditto for bathroom paints and concrete & metal primers, swimming pool paints, etc. (But I'd use a top
quality wall paint on a ceiling if you want better scrubbability and little spattering.)
3. The more a paint looks like an "earth tone" color (pronounced "kinda ugly color"), the better it will hide and
the less it will fade.
4. All things being equal, the glossier a paint, the easier it will be to clean, but the poorer it will hide.
5. "Blocking" which is a paint's tendancy to remain slightly sticky when dry is really due to the fact that the
adhesive nature of PVA is just plain hard to engineer out of it. In order to eliminate the problem entirely, you
need to switch to a different kind of plastic. PMMA paints are more expensive, but they don't have that problem
at all.
6. Titanium dioxide actually acts as a catylist in the chemical reaction whereby UV light from the sun
deteriorates the plastics that paints are made from. So, generally, white exterior paints tend to chaulk more than
other colors of exterior paint. DuPont coats their titanium dioxide pigments to minimize this problem, but lots of
paint sold here is made with titanium dioxide from countries like Turkey and Brazil where they simply don't do
that.
Knowledge is power, but only if applied in a timely fashion.
And here's Nestor's reply to a fella having problems with a green paint that likes to fade on him.
This ties in nicely with Piffin's notion about the reds in the paint fading and leaving the yellow component less effected.
----------
I'd guess the same as you did that your pigments aren't colorfast enough. If it were just the red causing a problem, then I'd have
an easy solution, but the fact that the green is fading is a problem that I know of no solution for.
You see, there are at least 4 different red pigments that are used in tinting paints, and they're all of different colorfastness; 1.
Toluidine Red which is the least colorfast 2. Napthol Red 3. Quinicridone Red, and 4. Perelyne Red (which is the most
colorfast, but is more of a maroon color than a blood red)
Now, I know that Sherwin Williams used to use Napthol Red for their red colorant, and just told their distributors not to use it
to tint exterior paints. The price of pigments has come down a lot in the last 10 years, so I think most companies are now using
the more colorfast quinicridone reds to tint paint.
What I'm suspecting is that your exterior paint was tinted with Toluidine or Napthol Red instead of the more colorfast
Quinicridone Red.
If you buy paint from a home center or hardware store, they'll use the same colorants to tint every can of paint regardless of
who's paint it is. So. if you're paying extra for Pratt&Lambert Paint, but you're buying it in a hardware store that also sells Behr
paint, then most likely they'll be using Behr colorants in your P&L paint, not P&L colorants. I'm thinking the P&L colorants
would use the most colorfast red pigment that would work since you are paying extra for premium quality paint. To get P&L
colorants, you need to buy P&L paint from a dedicated paint store. Paint stores will have a separate tinting machine for each
manufacturer's paint they sell, so if you buy Behr paint you get Behr colorants and if you buy P&L paint you get P&L
colorants.
The problem I'm having is with the green. So far as I know, there's only one green that everyone uses, and that's
Phthalocyanine Green (called "Thalo Green" for short), which is about the color of Hunter Green.
So, switching to a more expensive or less expensive paint won't make a difference in the green department simply because the
green pigment will be the same one.
In the case of the green, I'm wondering if you may simply need more UV inhibitors IN YOUR PARTICULAR CASE because
of your southern exposure. When paint companies mix paints, they'll use amounts of additives that are enough to prevent
problems MOST of the time. However, your particular situation may be one where you need more UV inhibitors than the
house next door.
I think what I'd try is to just splurge and buy a gallon of a well known premium quality paint like Pratt & Lambert or Benjamin
Moore's exterior top-of-the-line paint from a paint store in your area. When paint companies make paints, they'll also vary the
amounts of additives that go in paint that's to be shipped north as opposed to south to account for the more intense sunlight in
the south.
However, small paint companies will often be part of a "buying group" so that as a group they can place larger orders from the
paint manufacturers and get larger volume discounts. I don't know if the manufacturer can also vary the amount of additives it
puts in paints being sold to buying groups because the destination of the paint may not be known to the manufacturer.
I don't know for sure what's causing the problem, but if other red and green houses in your area don't fade as readily, the first
thing I'd try is a top of the line paint from a well respected name (like P&L or BM) purchased at a dedicated paint store
because there are differences in pigments and the kind and amount of UV inhibitors used in paints.
And if that doesn't help, what would help is to switch to an "earth tone" colorscheme that uses only inorganic pigments which all
have excellent colorfastness.
Knowledge is power, but only if applied in a timely fashion.
Is your brain glazed over yet? LOL
Knowledge is power, but only if applied in a timely fashion.
I saved it to read later when my eyes are not glazed like a Krispy Kreme!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
We call this, "Better living thru Chemistry."
The way we chose our paint color was we were driving around the town and I saw a dentist's building (an old renovated house) painted this darker brown, and I really liked it. I called the dentist's office and they gave me the name of the painter who had painted it. I called the painter and he said he had used Kelly Moore paint, so when we put our spec together I spec'd "Kelly Moore latex paint: Loam Standard #413. Sheen to be 1245 low".
What we got, and I had no reason to be concerned about it, was the Dunn Edwards Acri-flat paint.
What do you think of Kelly Moore paints? I think I heard a comment somewhere along the way that it was more a homeowner, do-it-yourselfer's paint than a "professional's paint", kind of inteferring that the quality wasn't as high in Kelly Moore as in some others.
We're at 2500' (considered the foothills) which doesn't seem THAT high but that's all in comparison to where some people live around here, which can be at 7,000'. I guess the UV light would have to be higher here than, say, the San Joaquin valley just an hour away.
I get back to the brown paint that National Parks use on their buildings (at least the ones I've seen). That's really the color I was after. Do you suppose they have the same problem?
Calico
That isn't a very high elevation. When you said Mountains, I infered more than I should have
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I figure I may as well drop some more of Nestor's knowledge on this thread while I'm at it. Seems we have alot of questions about paint showing up on BT and the more we know the better we can answer those questions...........and we can all certainly benefit from the knowledge anyway...and so can our clients. Besides............ you can now dazzle them with the info you have.......IF you can remember it all. <G>
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Why does paint quality vary so much?
The situation is this:
1.) No paint company makes ANY of the ingredients they use to make their paints with. They all buy them from chemical companies like Rohm & Haas, DuPont and Sun Chemical. Those same companies are willing to sell their products to any company wanting to make paint, so ANY company can make good paint. It depends entirely on the resins, pigments and additives they buy from their suppliers. You don't even have to have technical expertise as the chemical companies are the real experts on what resins work best where, what
additives work best with what chemistry of resins and what pigments give you the most bang for the buck.
2. Because each chemical company is continually coming out with newer and better technology at a higher cost,the job of the paint company management is really to decide on "how good a paint to make" based on their guestimate of what will sell the best. Every paint manufacturer will have a top-of-the-line paint that represents what he thinks is the best value for the money when the focus is on quality. Each will also make less expensive paints that represent their idea of the best value for the money when the focus is on price.
So, quite literally, when it comes to paint, you get what you pay for.
If you want the best paint, buy the most expensive paint. If you want the best value for your money, buy a "house brand paint" like Sears Weather Beater, Wal-Mart House Beautiful or Lowes American Tradition.
If you want a paint made by a company who intentionally buys the latest and greatest technology so that they can
advertise how much better their paints are than Sherwin Williams, Benjamin Moore or Pratt & Lambert, check out C2 Paint. C2 is excellent paint, but your not getting the biggest bang for your buck. Your getting a little more bang for a lot more bucks.
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EVERY paint company can make a paint as good as Benjamin Moore's best.
It's simply a matter of buying the best resins, additives and pigments from companies like Avecia, Rohm & Haas and Sun Chemicals. If you buy the same resins, additives and pigments that Benjamin Moore buys to make it's paints from, you'll end up with as good a paint as Benjamin Moore makes.
In fact, if you want to make a better paint than Benjamin Moore makes, all you need to do is buy better resins,
additives and pigments than Benjamin Moore buys.
One company that does this is C2 Paints at http://www.c2color.com/
You see, all of the chemical companies are always trying to push their latest and greatest technology on their customers (the paint manufacturers), but the paint manufacturers won't buy it unless they feel that the improvement in performance is worth the difference in price. (Just like you would if you were the top dog at
Benjamin Moore.)
C2 Paints intentionally buys the latest and greatest technology from the various chemical companies selling paint resins, additives and pigments. You make a better paint, but you pay a lot more. That is, you get a little more bang for a lot more buck.
C2 makes some of the best paint that can be made with existing technology. But, the purpose in doing so is so
they can present independant lab test results proving their paints are superior to Pratt & Lambert's, Benny Moore's and Sherwin William's best. And they are. But you're not getting a better deal.
With paint, you get what you pay for. But, in the case of house brand paints like Wal-Mart's "House Beautiful", Sears "Weather Beater" and Lowe's "American Tradition", the price of the paint is determined in advance by company management. As a result, the volume discount ends up resulting in an improvement in quality of resins or additives going into the can rather than a reduction in price to the retailer. (Just go to any caterer and ask what kind of meal you could get for $10 per person if you're hosting a party for 25 or hosting a party for 500.
Price is in fact the best indicator of a paint's quality, but the whole trick is to buy that most expensive paint from
the place that sells it the cheapest.
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Edited 9/26/2004 9:58 am ET by GOLDHILLER
Why today's alkyd ("oil") paints simply don't penetrate like the oil paints of yesteryear and what you can and can't do about it.
Those clumps of oil molecules (called "alkyd resins") are simply too large to penetrate well into wood no matter how much you thin the paint and no matter how much time it takes for that paint to dry. The alkyds are simply 10 or 20 times larger than an oil molecule and aren't absorbed by the wood the way oil is.
And latex paints penetrate even less.
How big is an acrylic resin? Well, a "micron" is a millionth of a meter, or a thousandth of a millimeter or roughly 1/25000 of an inch. A human hair is about 100 microns in diameter. The smallest thing you can see with the naked eye is 10 to 20 microns in diameter. Extender pigments used to make paint flatter are 10 to 20 microns in diameter. A red blood cell is 5 microns in diameter. A single "polymer colloid" (or acrylic paint resin) is about 1/10 of a micron in diameter, and the smallest pigment used in paint (black) is typically about 1/100th of ####micron in diameter. And, an oil based paint (or "alkyd") resin is much smaller still.
And finally, the real "oil based paints" that used boiled linseed oil didn't even have resins (which are "clumps" of molecules), but had oil molecules themselves as the binder. Because an oil molecule is about as small as you can get when it comes to a coating of any kind, and the old boiled linseed oil based primers had the BEST adhesion to wood because the oil would literally be absorbed right into the wood, just like water or mineral spirits are absorbed in wood.
So, basically, the reason latex paints don't stick as well to smooth surfaces as oil based paints is because of the size of the resins in the paint. Some latex paints stick better than others, tho, and it doesn't really have anything to do with the size of the latex resin, but what it's made from. But that's another topic
Since thinning an alkyd paint won't improve penetration, there is absolutely no advantage in using a slow drying thinner like
turpentine to provide ample time for that penetration to occur. All you do is increase the drying time of the paint without
improving it's penetration. This is why alkyd paints are thinned with mineral spirits instead of turpentine; the penetration ain't
gonna get any better with a longer drying time, so you may as well have the paint dry faster.
If you want better penetration (and therefore adhesion), paint the wood with either boiled linseed oil first (or Tung Oil) thinned
with enough turpentine so that it spreads easily and doesn't leave brush strokes, and then when that's dry enough to touch, paint
with your alkyd primer, and then within 24 hours of the primer, paint with your top coat.
That way, the oil penetrates for good adhesion. The alkyd primer crosslinks with the oil that's anchored deeply in the wood. The top coat crosslinks with the primer.
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Knowledge is power, but only if applied in a timely fashion.
Edited 9/26/2004 10:03 am ET by GOLDHILLER
Edited 9/26/2004 10:39 am ET by GOLDHILLER
Is Benjamin Moore consistently thought of as a high quality paint? Is it related to Kelly Moore paints?
Calico
"Is Benjamin Moore consistently thought of as a high quality paint?"
Pretty much so. But I'm pretty sure the SW Duration exceeds anything they currently have for the exterior. I think.
"Is it related to Kelly Moore paints?"
I have no idea.
Knowledge is power, but only if applied in a timely fashion.
Is there any general rule in how often a house built from Hardiplank should need to be repainted if it's painted with a good quality paint? Seven years seems way out of line to me, but I don't really know. We used Hardiplank versus wood siding so we wouldn't have to repaint often. We've had to redo some of the very exposed woodwork, which I didn't think was unreasonable, but there's not very much of that.
Calico
I have no knowledge or experience with Kelly Moore paints. So..I dunno would be the answer to your question.
But what I do know is that even if they had a good paint one year, doesn't mean they do the next. Paint companies are frquently "reformulating" their products. Sometimes for the better and sometimes for the worse.
I'm currently painting the exterior of a house with SW Duration. First used the stuff about 7 years ago and I can tell it's not the exact same product. And the folks in here at the SW store told me it had been reformulated. I hoping for the better of course, but I certainly have no complaints with how the "older" stuff performed. Used it here on this house first and the performance is just remarkable. Looks like it was painted a year ago.
As far as your fading problem...what I gather from Nestor is that perhaps the product you used was colored with a blend of the cheaper organic pigments rather than the more expensive inorganic pigments. And there may not be enough UV inhibitor in there either.
I don't hear you complaining about the paint wearing away prematurely so whether it's PVA or PMMA based, that part seems sufficient for your particular exposure.
I'd say get ready to hear a song and dance from the paint rep when he/she shows.
If you've read all these Nestor posts, I'll bet you'll be armed to the teeth to discuss the matter. You'll probably know far more than the rep does. Be prepared to see a raised eyebrow.
But none of that will remedy the fade problem you have. I'm thinking the resolution amounts to finding a paint comany that does use inorganic pigments to achieve the color you desire and also throws in enough UV inhibitor to stand up over the long haul. This might take a call or a few to various tech folks at a few different companies.
Maybe you should talk to someone from the park district and find out if they have fading problems with that color. Don't forget to take into account whether there's difference in exposure between their buildings and yours. Maybe theirs live in the shade most the day while yours is out in the blazing sun.
If exposure values are the same and theirs doesn't fade, you might want to purchase the same paint from the same company. Park district folks might not even know which paint they used, but someone should know who did the job and that person should know what product was used.
Knowledge is power, but only if applied in a timely fashion.
Yes, I also anticipate a song and dance act from the company. I don't know what my rights are in a situation like this, but I expect I will before this is over. I can't feature using their paint again.
I live very close to a large national park, so I may be able to find out what they use on their buildings.
Thanks for your ideas. As you said, it seems like the crux of the matter is type of pigment and amount of UV protection.
Another theory - Could it have anything to do with the fact that it is flat paint in that something like pollen (which we have a lot of in the spring) would adhere to and bake into the exposed surface? The thing that makes me think it's not the pollen is that the parts of the house that aren't sun exposed don't have a problem. They look fine. It seems like if it were the pollen, we'd be having the yellowish build-up everywhere, but we don't. So . . . . maybe I just answered my own question. What do you think?
Also, one more bit of data. There's a tendency for the discoloration to be "striped" in that it isn't discolored where the studs of the wall are. This is not a hard and fast, but a general rule. In other words, we have a vertical rectangle of lightly yellowed paint, and then a thinner vertical rectangle (stripe) of un-discolored paint which follows the vertical stud (at least that's what my husband says it's doing). This pattern repeats across the wall. Any idea what that might be about?
Calico
I'm thinking that the striping may be due to a phenomenon known as the Brownian effect. I don't have a link handy at the moment, but you can Google your way to it and an explanation, I think.
The basics of it all is that it is this "effect" that causes brownish stripes (mostly seen on interior plaster or drywall surfaces). Since your paint is already brown, it may be that the paint under there is also faded but the brown color has simply been replaced by an accumulation of dirt via this phenomenon......and so it looks to you as if it hasn't really faded or faded as much.
I haven't painted any Hardi siding yet, but I would anticipate the life expectancy to be similar to the old asbestos siding shingles of which I've painted numerous times. I can usually expect as much as twice the paint life on these shingles compared to wood siding with the exact same product.......applied in equal thickness.
I think this is because the thermal coefficient of the asbetos siding is relatively low (.7 ?) and so it doesn't move around much stressing the paint layer. On the other hand, wood siding tends to expand and contract quite a bit around here from one season to the next and so the paint needs to have the ability to keep up with this and still maintain adhesive intergrity. As the paint gets older and more dried out, it looses this ability and so starts to fail earlier than it does on the asbestos shingle. On the AS, the paint literally wears away and that's what constitutes "failure" and time to apply more.
A relative comparison I'm familiar with would be SW Super-Paint on these two different materials. On wood siding and trim around here, you can expect maybe 7 years on a single coat of SP. On the asbestos siding, maybe 12. Maybe a bit more....depending upon how fussy you are about appearance. These are houses that sit out in the blazing sun in the country. Some wood clapped houses we painted with the same product that live in heavy shade in town are still going strong some 15 years later. I drive by them all the time on the way to pick up materials.
The house I'm currently painting is asbestos shingle and I'm using SW Duration on it. This is the first time I've used the Duration on this material. If it performs anywhere nearly as well as it has on this Vic, I like to think I'm set for 20 years or more. Check back with me then and I'll give ya a report. :-)
Oh yeah. Your "rights" with the paint company will not likely amount to anything more than replacement price of the materials only. That's SOP for most building material related "failures".
This is why it's really penny-wise and pound-foolish to use "economy" materials in most instances. Take for instance the price of paint since we're talkin' about paint. I haven't grabbed any SW Super-Paint for quite a while now so I don't know the current price here. Let's say $28 a gallon for sake of discussion. SW Duration is curently $38. The house siding I just did required 6 gallons of Duration. That's a $60 difference to use the superior product. Some folks faint when they hear that $38 a gallon price. I say........whoopdyfriggin'dooo. LOL Based on experience with the two products I anticipate twice the life expectancy from the superior product. I already know which one I'm going to buy before I ever pick up the phone to have them start mixing my batch.
Knowledge is power, but only if applied in a timely fashion.
Edited 9/26/2004 11:56 am ET by GOLDHILLER
I couldn't agree with you more about not being penny wise and pound foolish. That's why we went with the Hardiplank. We wanted a really low-maintenance house. Same reason we used Trex for the deck. Neither of us are handy, so we knew it was worth it.
One of the problems, and I guess it may be a problem everywhere, is contractors only want to use what they're familiar with, and I can't blame them. I don't know if they sell SW paint in California, but I'll check. We were afraid to force a contractor to do anything, since we had opinions but no real expertise, and if something went wrong, they'd just point the finger at us and say "I told you so".
I did what I knew how to do to check out the Dunn Edwards paint. Went to the store, googled, etc. Oh, well!
That's really crummy, given that the least expensive part of the painting project is the paint itself, that they'd only be liable for the paint.
Thanks so much for your ideas. I'll check on that Brownian effect. One idea my husband had was that the studs were absorbing just enough of the heat to keep the paint from discoloring, or at least not as badly, as the areas where there are no studs.
Calico
Calico
Here's a link concerning the Brownian effect or Brownian motion as it applies to frame ghosting.
http://www.buildingscience.com/resources/misc/black_stains_on_carpet.htm
Knowledge is power, but only if applied in a timely fashion.
Thanks for the link. That's really interesting. It might be the issue, but I think in this environment, and given that it's outside, it's more likely the heat being tempered by the stud, but who knows?
Calico
Striping would presumably be due to a temperature-sensitive effect. The areas over the studs will be warmer or cooler (generally cooler when hit directly by the sun) and that may make a difference in how the paint reacts.
Very interesting.
I knew bits of this, but not the chemistry. This helps put a lot of it together.
But one very minor clarification.
"Wood stains use dyes, paints ONLY use pigments."
I that that should be wood stains use dyes and/or pigments .....
From M-W
Main Entry: 1enam·el
Pronunciation: i-'na-m&l
Function: transitive verb
Inflected Form(s): -eled or -elled; -el·ing or enam·el·ling /-'nam-li[ng], -'na-m&-/
Etymology: Middle English, from Middle French enamailler, from en- + esmail enamel, of Germanic origin; akin to Old High German smelzan to melt -- more at SMELT
Main Entry: 2enamel
Function: noun
1 : a usually opaque vitreous composition applied by fusion to the surface of metal, glass, or pottery
So my guess is that enamel paints are ones that emulated (hard and glossy) the fired on glass/ceramic coatings.
"But one very minor clarification.
"Wood stains use dyes, paints ONLY use pigments."
I think that should be wood stains use dyes and/or pigments ....."
Ah! You caught that too, did ya?
Shoulda edited for him, but I didn't.
I'll give the guy that small omission. He's got alot on his mind. :-)
Knowledge is power, but only if applied in a timely fashion.