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WHAT IS THE PROCESS FOR PAINTING LATEX OVER OIL BASE PAINT? I WAS CURIOUS WHETTHER A SPECIAL PRIMER IS USED OR IF SANDING OR OTHER PREP IS REQUIRED ???THANKS FOR YOUR TIME.
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Replies
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I'm going to start this slow to see if your following it.
Prep a small area at an inconspicous spot not at eye level. Paint a sample of the finish latex paint you want to use on that spot. The next day take a piece of masking tape and firmly press it on to the sample. Now pop the tape off quickly and see if it took the latex paint with it. If it did you need special prep and or prime techniques for a good bond. If it stayed on through this test you should be able to paint as you prepped your sample.
So please stop shouting and tell me how your sample worked.
joe d
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YEAH!
*Always start with making a sample of something if you are unsure about the outcome. In this case take a small area of whatever it is you're painting and make it your test site. For interior application I would make sure all your oil substrat is scraped and sanded to give the primer tooth. Then I would apply pigmented shellac, also called stain killer primer (Bullseye, Kilz, are some of the names), which is an alcohol base product. Allow the primer to dry completely, it's fast usually within an hour. Then apply your finish coat of paint. Wait a day, and do the masking tape test by applying tape to the spot and pulling it off to see if any paint came up. If not, I would say you're safe to proceed. Making a sample can be time consuming but in the end it saves alot of heartaches.
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Bullseye 1-2-3 is NOT shellac based primer. It is a water based primer. It is still a great all purpose primer, but the shellac based is BIN (both are made by William Zinsser Co.)
When painting latex over oil base, it can be done successfully INSIDE, but not successfully OUTSIDE.
Inside the home you have climate control, and the paint does not expand/contract very much. Outside it will expand and contract tremendously. Because latex paint and oil based paint expand and contract at different levels, they will separate from each other, and you will have peeling and flaking in short order. (THIS IS OUTSIDE APPLICATIONS)
On inside applications, use a good quality primer made for glossy surfaces, OR sand the glossy surface to degloss, OR use a liquid deglosser to degloss the surfaces (very messy and smelly).
Like the other gentlemen said, try a small area in an inconspicuous place to start.
If you have any questions about the use of primers, and what surfaces to use them on, go to this site and check them out.
PRIMERS
Just a thought...
James DuHamel
*Prep is always needed before painting over anything! 90% of painting is preperation. Sanding gives the tooth for the next coat.Usually it's not a good idea to put oil over latex without a transition coat because latex will expand and contract better than oil which tends to dry harder and not be as flexible. Without seeing the condition of your paint, I'm assuming what you're painting over is basically sound, the comment about testing is a good idea.Latex can go over oil on the exterior, in fact most painters still use oil primer, under a good acrylic topcoat. As on the interior just don't use oil over latex without the transition coat.
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what they said, especially mr.DuHamel. Ditto...
(I always prep and prime any and all surfaces to be painted, included cleaning the surface thoroughly first. Paint just doesn't stick that well to dirt... neither does tape for that matter. Of course, if you practice with a Purdy for a few years, you no longer need tape... which reminds me - if you want a quality job, use QUALITY tools :)
oh yeah - what you're looking for is the Caps Lock button - over above "Shift" on the left side of your keyboard...
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Well almost everything Mr. DuHamel said.
The only thing I would respectfully disagree with;
"Use a primer made for glossy paint OR sand.."
Always sand! That's important, especially for
cabinet grade work. I even sand if I use a
deglosser. Primer or deglosser will not remove the
grit embedded in the paint.
You can paint acrylic over oil on exteriors, just
don't do the opposite. Most painters prefer oil
primer with acrylic topcoat. We have painted many
old houses with a quality acrylic as long as the
basecoat was solid and not chalking. In this case
we only prime the bare spots. As in everything
Prep is the #1 consideration. Then use quality
materials so you don't waste the prep
time.:)......
*Very good points by all...One thing I must respectfully disagree on though... oil based primer is NOT paint. It is an entirely different animal. Oil based primer is best used for new wood, because it will absorb into the wood pores much better, and penetrate much deeper. When refering to the application of Acrylic paint over an oil based primer, it is not the same thing as Acrylic paint applied over an oil based (or alkyd) paint. Primers are made for specific purposes. There are as many different types of primer as there are situations to use them. Primers are a sealer, bond coat, and stain blocker all in one (the good ones anyway). The primers chemically bond to the surface they are applied to. The top coat of paint is chemically bonded to the primer. This is a "system" and as long as the system is used, you will get a great paint job. The longevity of the paint job will depend on many factors.Climate plays a major role in what types of primers and topcoats are used, and when and where to use them. Although I may give advice and tips on painting, it is a general type of advice. I may not live in the same climate as some of you, therefore I would have to do my priming and painting a little different.When using a deglossing agent, or sanding, or using a primer made specifically for glossy surfaces, the same results are had. Sanding does indeed give some teeth for the new paint to adhere to. The primer on the other hand, is what seals and bonds the surface. It will seal in all imbedded dirt and debris, and prevent it from "floating" to the surface. I personally sand with very fine grit to smooth the surface on trim, cabinets, and fine woodwork. I do this because I use a sprayer more often than not, and spraying leaves a very smooth surface. Any debris in the surface will show.My humble opinion...James DuHamel
*Maybe I'm wrong, but I don't think any of these primers actually contains shellac. they were developed as alternatives to shellac (which can still be used as a primer) and pigmented to provide some hide. Anyway, shellacs are alcohol-based, water makes shellac go waxy.The sanding and primer are invaluable precautions: if the entire paint job doesn't stick you'll have a horrible mess. But no one has suggested regular primer, which should give better "hold out," a more consistent sheen to the topcoat (or so i thought). The pseudo-shellacs are more for stain/knot concealment and other problem surfaces or, in my case, when you're in a hurry. They're ready for topcoat in little over an hour. On the advice on the paint shop, I also used the oil Zinnsner (sp?) to prime "preprimed" moulding to avoid raising the grain; results were very good.Always looking for tips on the black art of painting, andrew
*a few years ago, faced with having to repaint exterior, moderately weathered oil based topcoat on doors & trim, I tried a test:1) lightly scuffed the old alkyd topcoat w/ 80grit(?) sandpaper, then painted test patches2) latex top coat directly on the old oil top coat3) latex top coat over LATEX primer over old alkyd top coat4) latex top coat over ALKYD primer over old alkyd top coatall paints & primers were the top grade of Ben Moore exterior paints. My environment is So Calif coastal, facing southwest (worst direction).A week later, I did the tape "peel off" test.# 4, latex over oil primer, was BY FAR the best adhesion, it basically didn't peel. The others peeled off to varying extents, #2 was easily the worst.I have become a believer in alkyd primers, unless it's brand new wood that hasn't weathered, in which case latex primer (that others rave about) is probably OK.
*Hey Andrew,I only mentioned that the Zinsser brand Bullseye 1-2-3 wasn't a shellac based primer. Zinsser makes a shellac based primer (real shellac according to them) that is called BIN. KILZ makes one too. They are both DENATURED alcohol based. I was not saying that shellac based primer should be used for the application mentioned, only that the Bullseye 1-2-3 was not shellac based.Everyone has their own opinions about what primers are best, and where and when to use them. I have no problem with that at all. Each area of the country is different, so it makes sense that different products, techniques, and styles will be used.I have tried every combination imagineable, and available to me. I have chosen what works best for me, in my situations. I offer a minimum of a 3 year warranty on all paint jobs, and in order to do that, I have to make sure that the surface is properly prepped, moisture penetration problems are solved, and surfaces are properly primed and top coated. I can only tell you what works best in my area of the country, and on the jobs I work on. I am like you, and I am always looking for information to make my paint jobs look better, last longer, and take less time to do. I am one of the few people I have ever known that actually LIKES to paint. For me, it is easy money, and something I enjoy. Just my humble opinion...James DuHamel
*I'm amazed at all of the disagreement. This isn't an opinion area, I wouldn't believe, but one that could be substantiated fairly positively. The expansion/contraction issue is easy. No alkyd over acrylic. On the other hand, the expansion argument doesn't explain why acrylic can't go over alkyd, so James DuHamel may need to adjust his argument.Adhesion may be the primary reason not to put acrylic directly over alkyd, and this would hold inside or outside, as tom herman illustrates. Primer is appropriate beforehand.
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I don't know if I'm that amazed over the disagreements. As with many other applications, there are various methods that produce acceptable results. In the case of painting and finishing, some of the results are not seen or known for several years, so the superior answer, if there is one, is harder to find. Manufacturers probably have some pretty good data, but it seems difficult to find among the promotional material.
Sorry, but I must disagree with Steve, in his response above, as well as with the others who discuss the expansion issue. If your recently applied paint film is so thick as to have its own expansion and contraction properties, you're in trouble. Paint adheres (when properly applied, of course) to the underlying substrate, whether that substrate is more paint or the base wood, steel, etc. It is the underlying base that expands and contracts with changes in temperature or moisture, but the paint moves with it, NEITHER FASTER OR SLOWER. When the paint ceases to move adaquately, it begins to crack, or rarely, peel (peeling is usually a moisture problem). Alkyd, oil, latex, or acrylic, -it doesn't matter what the resin or vehicle was, once it's fully cured. You can sandwich 'em all you want as long as each one is cured and has adaquate tooth, be it physical (sanding) or chemical (de-glossers or 'systems' such as primers). If any layer has lost its elasticity, the paint job will eventually fail. If any layer does not adhere to the next, it will also fail.
Simple, eh?
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Not so simple, eh?
Latex and alkyd paints (NOT primers) expand and contract at different rates. That's a fact.
If you paint acrylic over alkyd on exterior surfaces, it will fail. Guaranteed, UNLESS you take precautionary measures, remove the topcoat, or use some other method to get rid of the alkyd paint. The acrylic and the alkyd expand and contract at different rates, and when this difference occurs, the paint loses it'e adhesion. And rest assured, paint CAN lose it's adhesion.
If you apply alkyd over acrylic, you run into the exact same problem, only you add another. Moisture vapor will pass through acrylic paint (one of its benefits) and will NOT pass through the alkyd (one of ITS benefits) You will actually have moisture trapped beneath the alkyd surface, and the paint will fail. Not only will it fail, it will peel.
I do not come to all of this on my own. I have taken all of this directly from the findings of the Haas Paint Institute, which is the major testing lab for all manufacturers, and independent companies. They have tested paints for over 50 years, and this is THEIR findings. Because it is THEIR findings, and the paint companies have all contracted them to test their products, the paint companies themselves have adopted these guidelines.
Interior is NORMALLY climate controlled, so the expansion/contraction issue is not so strong.
It never ceases to amaze me the limited amount of knowledge that most Americans have when it comes to painting. They seek out each others opinions and advice, but never go directly to the manufacturers, or the testing labs. These are the people who REALLY know what's what with paint. Unless you are getting your info from someone testing and using the various paints under extreme conditions, then it amounts to no more than an opinion. An opinion is all I offer.
Just my humble opinion...
James DuHamel
*James, while I agree with you about the primer my point was you CAN paint QUALITY 100% acyrlic latex over oil on exteriors. As LONG as the paint is not peeling, chalking, alligatoring, checking or any other conditions that would indicate previous conditions. On the other hand putting oil over acrylic is not the same problem because oil dries harder than acyrlic,(which is more elastic than oil), CAUSES alligatoring and checking because you are applying relatively harder coats over relatively softer coats. Under influence of changes in temp, the paint film expands & contracts. If the top coat is not elastic enough it will crack. On new wood the longer the priming coat is exposed to the air the greater the oxidation and the harder the surface. Up to a certain limit, this is most desirable for a primer. Undercoats should always be harder than outer coats. As for your lab that has been testing paint for 50 years, that is great, to a point, but some of this paints haven't been available for 50 years. As a 3rd generation painter here in the midwest,A pretty good lab as far as weather changes) we have been testing these theories in real world applications since latex has been commercially available in our area (late 50's). We can even show people these "labs" still looking great. In fact we use to be one of the companies the paint chemists sent paint to test and I remember my dad working with the chemists of a regional manufacturer to develop some of these paints, but James is right in that there are regional differences and after all is said and done these ARE just opinions about what has worked for each of us in the past. Barry (never heard a humble opinion) Elings...........................
*Amen Barry!I also use the great outdoors of Southeast Texas as my "lab". I only refer to the Haas Paint Institute because these are the guys who study the chemical makeup of paint, and also test the VOC limits for the EPA. They have been doing it for various paint manufacturers, gov't, etc... FOR 50 years, not testing paint that is 50 years old.I live in a hot, humid, chemical and salt laden climate that plays heck on exterior surfaces (whether paint or some type of permanent siding product) Oil paints have always been a problem here because of moisture penetration from inside the home, and because of the chemical and salt.Acrylic Enamels have come a very, very long way in the paint world. With the lower VOCs allowed in alkyds, and with the greater concentration on acrylics by the paint companies, alkyds are fast becoming extinct. Almost every major paint manufacturer has indicated that they will start slowing the production of oils, and increasing the production of better acrylics. These acrylic enamels are going to basically be a very hard, plastic shell that is weatherproof, climate resistant, and lasts a long, long time. With the technology available today, tomorrow's paints will be awesome.I in no way mean to infer that all of the info I share is "how it should be done, all else is wrong". I share info with people from all over the country, and I learn something new everyday. I love talking with other painters because there just isn't a whole heck of a lot them around anymore, and these painters are the ones who are out in the field using these products everyday. I do, however, find quite a few that tell me "use Sherwin - Williams, Benjamin Moore, etc... (or some other brand specific paint simply because they have always used this paint) or your paint job will fail!" This is nothing more than brand name addiction, and carries no true meaning as far as how these paints perform when compared to other paints. I always try to learn about various brands, how they held up, what techniques are being used, etc... When someone comes along and tells me "do it my way, or you're wrong", I tend to think they are not very informed or experienced. The people here at BT have all been sharing how to, when to, why to, etc... about every kind of paint, primer, equipment, etc... I love the exchange of ideas and info. Thanks to everyone here who has been sharing.As for "never have heard a humble opinion", a lot of people here at BT that have been around a while will offer their humble opinions regularly. These are true, honest to goodness, HUMBLE opinions. We offer them in the hopes that we can make people understnad that they are indeed opinions, and not what we consider the gospel truth. We learn by trading information, and I am always learning.Have a good day Barry! James DuHamel
*Hi James;Good post. Nothing to disagree with there. :)Actually the humble opinion thing was my feeble attempt at a joke and I did understand the 50 yr. thing, just my way to make a point, I guess.It is funny about the brand loyalty, around here the "regional" stores far outsell the "big" name stores and most everyone has his favorite. I, like you, am one of the few guys on this BB who enjoys painting and probably one of fewer still with a painting background to become a remodeler. I too am amazed at the advances in paint products in the years since I was exclusively painting.Although I'm as good as putting my thoughts on "paper" as many of you on this BB I enjoy the exchanges of information and marvel at the way the net has made keeping up on new and different techniques, in all phases of construction, easier and faster. Like my Grandpappy always said, if you didn't learn anything today you must be dead!By the way, I have family in Corpus Christi, where are you in SE Texas?To borrow from another BB "Paint safe out there" ;)Barry......................
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I have a humble opinion as well. I'm a painting contractor and renovator/house builder here in Canada specializing in early homes. I tell my clients with older homes with no or poor vapor barriers that all paints will fail anywhere there is a warm space behind their warm walls unless as the early homes did there were lots of air leak areas that vented moisture back and forth in the building rather than trying to squeeze it through the painted surfaces.
For best adhesion over oil paints use a high adhering oil primer or latex blocker like Sherwin Williams Pro Block.
This gives the new coat of latex something to cling to. To increase the paints life use a flat paint that is porous, use satins where a certain amount of cleaning is necessary and for high traffic doors and frames you will never beat an enamel since the easticisers in the latex semi glossses retain oils from hand traffic.
On this painters Victorian house in Canada I use oils and expect to have to touch up minorly every 3rd year more so after 6 and recoat after 9 or 10.
For exteriors in Latex you might want to add a mildewcide to your paints if this is a problem in your region.
*James has this right on - Zinnser is actually shellac based. Not sure on the Kilz brand. When I was in college, I worked for a local hardware store, and had the opportunity to talk to the factory reps quite a bit. They educated me as to the mysteries of paint, and later I learned the secrets of the trade from a few long time locals.James - re: the 3 year warranty. I used to paint signs on the side (more fun and artistic than walls!). Yesterday I saw a box van I had painted in '92. The paint looks the same today as it did then. I have to say, I am impressed that it's lasted so long! Goes back to surface prep, quality tools and quality product. Count me in the group of folks that actually "likes" to paint. To me, it's one of the easiest jobs as well - if you do it right.
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I'm aware of the gradual extinction of oil-base for VOC/environmental reasons. But is there any substitute for exterior oil-based PRIMERS? I won't be using latex any time soon in a wet location -- moisture moves through it TOO freely (I'm thinking of backprimed, sealed materials where there just isn't going to be much moisture trying to get out except what the paint first lets in). Oil primer, latex over, appear to work great.
*Oh, I like to paint -- for the first 20 minutes. Then I want to go do something else.Re Zinsser, the B-I-N is shellac based while Bulls-Eye and Cover-Stain are latex and oil, respectively. http://www.zinsser.com/priseal.htmlJames, what goes around comes around. I just responded to sawdust's general reference to "zinsser." WHY they have to gice such stupid and unmemorable names to their products I don't know. Kilz has "Total One," "Kilz," "Kilz Ultra," "Klean Kote," "Kilz 2." etc. http://www.kilz.comAre Cover-Stain and Kilz/oil comparable? Kilz is the preferred primer around here, although it dries about as fast as you can brush it out and skins over pretty easily. The paint shop claims the Kilz-type primers have less consistent topcoat holdout/sheen vs. regular primers ... and the quite helpful Kilz site itself says, "KILZ is recommended only as a spot sealer on exterior applications and is not intended as a whole house exterior primer. For large scale exterior priming, especially on wood substrates, KILZ 2 or KILZ Total One are recommended. Where a rust inhibitive primer is indicated, use KILZ Total One."
*Hey Andrew,That's exactly what I said in my first post. Even gave the Zinsser web site. James DuHamel
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WHAT IS THE PROCESS FOR PAINTING LATEX OVER OIL BASE PAINT? I WAS CURIOUS WHETTHER A SPECIAL PRIMER IS USED OR IF SANDING OR OTHER PREP IS REQUIRED ???THANKS FOR YOUR TIME.