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  #1  
Old 06-07-2011, 10:58 PM
chaoticbear chaoticbear is offline
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How to make oil-based paint dry?

Tried to search, of course, can't use "oil", tried "alkyd" to no avail.

I painted some cabinets with some high-gloss oil paint marketed for floors last Wednesday. Two coats of it. It's certainly dry to the touch, but in several areas, it's not dry all the way down, meaning that if i set a ceramic bowl there, it'll leave a circular indentation in the paint, and one can easily dig a fingernail in to parts of it.

It's been a week, though!

Tried a fan for several days, and although it's helped, this seems to be beyond the scope of the range of drying times offered online. Can I just wait this out, or do I need to do something additional to it to make it dry, or (oh heavens no) strip the paint off and start over?

It's a beautiful color, but I really would like to have functioning cabinets again.
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  #2  
Old 06-07-2011, 11:16 PM
Joey P Joey P is offline
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If you're in a humid area maybe cranking up the AC will help (or running a dehumidifier). I beleive I've heard that adding some paint thinner (naptha, mineral spirits etc) to the paint will help it dry faster. But that's not really an option at this point.
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  #3  
Old 06-07-2011, 11:28 PM
TehBearJew TehBearJew is offline
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I remember my painting instructor in art school explaining how oil based paints in general, don't dry, but cure..some very very old and famous oil paintings have still not cured completely and if the mixture is not ideal, the oils will eventually slide down the canvas by gravity and form lumps.

That being said, dehumidifiers won't probably do much, but leaving them in a warmer area with the predominant face up to 'cure' might help.
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  #4  
Old 06-07-2011, 11:34 PM
Joey P Joey P is offline
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Originally Posted by TehBearJew View Post
That being said, dehumidifiers won't probably do much, but leaving them in a warmer area with the predominant face up to 'cure' might help.
Not what I was aiming at, but coincidentally, a dehumidifier does result in a net increase in room temperature. Technically they absorb and dissipate the same amount of heat from the two sets of coils but the fan motor and compressor will create their own heat as well. But that's not really ideal. What about a blow drier on the wet parts of the paint?
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  #5  
Old 06-08-2011, 06:19 AM
chaoticbear chaoticbear is offline
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Oh no. Fuel for the fire; my roommate has been wanting to split the costs of a dehumidifier with me for months now. I don't see the point, if it's 95 degrees outside, I want the air on anyway. I'm going to see if we even own a blow dryer. Unfortunately, I didn't have the technical skills to take these shelves out - it's a very old built-in cabinet with glass doors, and after how much paint has been slobbered on that thing over the years, I don't even know how they're affixed.
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  #6  
Old 06-08-2011, 06:27 AM
Joey P Joey P is offline
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Let you're roommate know that running the dehumidifier without the AC will heat the house and the AC is it's own dehumidifier (look at the water draining out). They are both the same exact thing. The only difference is that the dehumidifier is all inside the house and the AC has one set of coils outside the house to dump the heat.
IOW, if you want to dehumidify the house and it's 95 outside, run the AC.
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  #7  
Old 06-08-2011, 08:10 AM
ratatoskK ratatoskK is offline
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I'm not a painter, but at this point I think you will have to just wait it out and hope it cures in another week. Put the pieces in a non-humid area to dry. If it doesn't you may have to strip and repaint. It sounds like you may have applied the paint too thickly or did not allow the first coat to completely cure before you applied the second. If you live in a humid area and have to repaint, you could consider adding some drier to your paint.

Forget the hair dryer, etc., those ideas won't work in my opinion.
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  #8  
Old 06-08-2011, 08:46 AM
thelabdude thelabdude is offline
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My guess is that the paint was defective and will take a long time if ever to harden. Oil base paint requires what are called driers. Lead compounds at the level required were safe and effective. Unfortunately, due to stupid, unscientific federal laws, other, less reliable, and no safer materials are used. Also due to other air pollution laws, many oil base paints use isopropanol as part of the solvent. The longer and warmer the storage, the more the alcohol breaks down the polyester in the resin backbone.

Modern oil base paints, most of the last 100 years, contain unsaturated oils such as linseed or soybean. The oils are chemically combined with a polyester backbone. When they dry, first the thinners evaporate, and then oxygen in the air forms links between the unsaturated fatty acids from the oil. The curing is a hockey stick thing, rapid at first, but continuing slowly for years. A number of things can go wrong to keep the paint from forming a hard film. The thicker the paint, the longer it takes too.
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  #9  
Old 06-08-2011, 09:37 AM
sachertorte sachertorte is offline
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I've been painting cabinets these past few weeks. I've discovered that very thin coats are essential. Any area that has a thicker coat is not going to dry for a very very long time. For me, these accumulations occurred on the inside of the cabinet, where I don't care about them and wasn't paying close enough attention. I scraped them down to let them dry. I imagine if I hadn't they would still be tacky.

Also, the instructions on my can of paint says the paint is dry to touch in 6 hours but to wait at least 24 hours before the second coat. Did you do this?

Also, the instructions said that full cure occurs after 7 days, so I waited a week before putting the hardware onto the cabinet doors.
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  #10  
Old 06-08-2011, 09:46 AM
garygnu garygnu is offline
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Quote:
Originally Posted by TehBearJew View Post
I remember my painting instructor in art school explaining how oil based paints in general, don't dry, but cure..some very very old and famous oil paintings have still not cured completely and if the mixture is not ideal, the oils will eventually slide down the canvas by gravity and form lumps.

That being said, dehumidifiers won't probably do much, but leaving them in a warmer area with the predominant face up to 'cure' might help.
To be specific, oil paint dries via oxidation. You can mix stuff in before you paint to make it dry faster, but once it's on the wall, there's not much you can do.
I suppose, theoretically, you could blow oxygenated air at it or something. Got Nitrox scuba certification?
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  #11  
Old 06-08-2011, 10:32 AM
constanze constanze is offline
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Quote:
Originally Posted by thelabdude View Post
My guess is that the paint was defective and will take a long time if ever to harden. Oil base paint requires what are called driers. Lead compounds at the level required were safe and effective. Unfortunately, due to stupid, unscientific federal laws, other, less reliable, and no safer materials are used.
Funny how for centuries artists using lead-based paint used to go crazy and die prematurly from poisioning. Stupid unscientific effects!
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  #12  
Old 06-08-2011, 11:45 AM
thelabdude thelabdude is offline
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Originally Posted by constanze View Post
Funny how for centuries artists using lead-based paint used to go crazy and die prematurly from poisioning. Stupid unscientific effects!
They were using true lead base paint, not the stuff in use in the 70's when the stupid law was passed. The SD is supposed to be an oasis free of ignorant fear mongering.
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  #13  
Old 06-08-2011, 11:59 AM
beowulff beowulff is online now
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Quote:
Originally Posted by thelabdude View Post
They were using true lead base paint, not the stuff in use in the 70's when the stupid law was passed. The SD is supposed to be an oasis free of ignorant fear mongering.
How do you explain the dramatic drop in serum lead levels in children since the ban?
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  #14  
Old 06-08-2011, 12:33 PM
chaoticbear chaoticbear is offline
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Quote:
Originally Posted by sachertorte View Post
I've been painting cabinets these past few weeks. I've discovered that very thin coats are essential. Any area that has a thicker coat is not going to dry for a very very long time. For me, these accumulations occurred on the inside of the cabinet, where I don't care about them and wasn't paying close enough attention. I scraped them down to let them dry. I imagine if I hadn't they would still be tacky.

Also, the instructions on my can of paint says the paint is dry to touch in 6 hours but to wait at least 24 hours before the second coat. Did you do this?

Also, the instructions said that full cure occurs after 7 days, so I waited a week before putting the hardware onto the cabinet doors.
I didn't wait 24 hours. And I applied it as thickly as would have latex paint. I guess I treated it exactly the same, except harder to clean and smelling much worse.

So, since these are mostly inconspicuous, we may just restock the cabinet and get along with our lives. The paint is dry, it's just soft still in certain spots.

And re: dehumidifier: we both know that's how they work. She is just ADAMANT that it has to be more efficient than running an A/C. I can almost see her point for times when it's humid and not particularly hot, but I'd still rather be chilly and dry than have to spend a couple hundred on a dehumidifier. And it's Arkansas - we have 8 months of hot anyway.
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  #15  
Old 06-08-2011, 02:17 PM
picunurse picunurse is offline
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Did the cabinets have latex paint on them when you painted the oil? If so, they won't dry.
They may be dry to the touch, eventually, but the paint will peel.
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  #16  
Old 06-08-2011, 02:56 PM
thelabdude thelabdude is offline
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Originally Posted by beowulff View Post
How do you explain the dramatic drop in serum lead levels in children since the ban?
Despite the paint red herring, there have been some efforts to go after real problems including lead in gasoline.
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  #17  
Old 06-08-2011, 08:32 PM
gatorslap gatorslap is offline
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There's a product called Japan Drier to make oil-based paint dry faster, but it has to be added to the paint, so it's too late now. Pretty sure there's nothing you can do other than strip the paint off and start over, at this point.

Were the cabinets previously painted? As picunurse said, oil-based paint won't properly cure if applied directly over latex (or on some other surfaces, for that matter). In that situation you would first apply an oil-based primer (or strip down to the wood). Did you prime?
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  #18  
Old 06-09-2011, 10:07 AM
chaoticbear chaoticbear is offline
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Oh, so in other words, I actually just did *everything* wrong. I thought that latex wouldn't stick to oil, but assumed that oil would stick to latex.

And at $30 a can for the paint, you think I was buying primer, too?

::sigh:: I guess I know what I'm doing with my next weekend off. :/
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  #19  
Old 06-09-2011, 01:17 PM
thelabdude thelabdude is offline
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Don't discount my point of paint aging poorly. Oil base paint isn't very popular now, and who knows how long it may have set on the shelf or a hot warehouse. Try applying a thin coat to some bare wood and see if it dries.
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