I am doing a little painting today. The instructions say dry to the touch in 20 minutes can be recoated in 12 hrs. Of course I am putting my second coat on in about an hour or so, once it’s dry, and I haven’t seen any problems. Any good reason for this 12 hr wait time?
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Yes, absolutely!
When you apply that first coat of paint, it is several molecules thick. when it is tack dry to the touch, you are pnly feeling how dry the top two or three molecules are. The layer of paint you put on is surface dry only. When you go over it all again prematurely, you disturb the underlying thickness that is still in the process of curing. results vary from creating a more uneven, mottled finish, to peeeling the whole thing off , to creating greater possibility for future blistering.
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isn't that mils????
let's go help watch his paint anyways..
you make it home okay???Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Home but not OK - I'm sick of that much road time on top of being just plain sick
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Speak the truth, or make your peace some other way.
Edited 4/4/2006 11:35 pm ET by dustinf
get better...
fly the next time
good wishes bud....
go watch the paint dry...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Piffin, What are you saying about several molecules thick?
Did you mean mils or am I due for a learning experience?
be hitting the books again
'Nemo me impune lacesset'No one will provoke me with impunity
Naw, I understand him perfectly, that's just his figure of speech.
Mills are a measurement of thickness in thousanths of an inch.I don't know how thick a molecule of paint is in mills but I know a layer of them ( one coat) piles up a few molecules thick and dries that way, the ones exposed to the air first.Anybody who wants to figure out how thick a molecule of paint is, can translate it to mills, not that it is important. We just have to keep enough hot air moving to dry this girls paint for her.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I think that it is a little more complicated than that.Latex does more than just drying from the evaporation. After it dries the "globs" start knitting together.Try scrubing the paint, even aftere a couple of days. Then after a couple of months.IIRC they talk about 1-2 months for a full cure.
HEY!!!!!
I asked first...
wait yur turn....Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
it's kinda an ideal
like my wife would like me to last closer to twenty minutes instead of two
w/ painting you have more control
hope you have the most ideal conditions for your indiscretion
never a dull moment around here...
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
even if all we're doing is sitting around watching the paint dry...
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Eleven hours and fifty-eight minutes to go.
I have learned tha hard way to believe what the finish mfgrs say about waiting for a second coat. Some will say to recoat within an hour, or wiat until after 12, and I have provenm that they are right. It's no fun stripping off a failed finish.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Piffin is mostly correct - except for the molecules part; those are measured in microns, not mills - you should believe the manufacturer's label instructions. If they say 12 hours, it's because they have had problems with re-coating sooner than that.
Take it from an old paint company guy, re-coating too soon can cause problems even if it seems ok while you are doing it. Think of the dry surface being like the skin that forms on top of an open can of paint. It holds in water or solvent, as the case may be, and tends to keep the paint below that skin from drying. When you put another coat on too soon, the new paint also starts to dry from the top down, shrinking in the process, and may wrinkle the dry part of the first coat or at least break some of its bonds with the still-wet paint underneath, causing early failure of the system.
Except for lacquer and shellac, which reach full properties as soon as the solvent comes out, paints go through several stages as they dry:
Set = still wet but no longer brushable.
Dust Free = dry enough that dust won't stick, but handling can leave fingerprints.
Dry to Touch = most of the water or solvent has released from the film and it can be handled gently.
Dry to Recoat = The resin has cured sufficiently that a second coat will not damage it.
Full Cure = the film is as hard and durable as it will ever be. This may take a month or more with some paints, as little as a day with some fast-drying resins like vinyl toluenes.
Label times are usually based on 70 degree F and 50% humidity. If the temperature is higher and/or humidity lower, dry times will be faster.
Now aren't you sorry you asked?
BruceT
You are right--I made the mistake of painting two coats of oil-based enamel in one day and the first coat made the second drag and not flow. After a couple days of letting it all dry, I sanded it down and started over. Not fun.
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I am not sure what type of surface you are painting but each type of paint and surface will react differently to each other. In my area many high end homes are using a veneer plaster which slows the curing significatly.
In commercial work on regular wallboard we can prime and successfully apply a second coat within 2 hours. Using a commercial product, like Moorcraft, will allow for faster re-coats.
Of course watching paint dry can fill a day.
Good luck,
Jon
"we can prime and successfully apply a second coat within 2 hours"Since primer is a different animal, that can sometimes be done, but what you refer to as a second coat is relaly the first coat of paint and manufacturers instruictions still prevail before applying a second coat of it.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
True, the second coat is really the first of what should be two finish coats.There is definitely some flex in manufacturers directions. As mentioned above. the temperature and humidity can affect the ability to re-coat a relatively fresh base coat.Thanks for the clarification Piffin.
true, there must be a hundred variables in painting. My painter's son went to college to study chemical engineering. he's making better money taking over the old man's business, but it is amazing how much of his schooling he applies daily on the job to uinderstanding all those variables.And to boot, the kid sets me straight sometimes;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
You mean there is science behind paint?!? Who would have thought college could provide basis for a rewarding career in the trades?Must be a diplomatic guy to correct you Piffin;)All the best, Jon
The thing with the 12 hours is, if you're still there 12 hours after you started painting, or if you're back again less than 12 hours after you finished painting, then you're working way too hard. ;-)
-- J.S.
I would have to agree. Who said Painting has to be labor?Jon