Acrylic paint that never dries?

[David Hingtgen]

Long story short, I painted something with "cheap craft paint" like you find at Hobby Lobby, Michaels, etc (it was a PERFECT match and had the same amount of gloss so I wanted to use it) and it just doesn't seem to fully dry. It's a fairly glossy paint, and I did put 6 or so layers to cover (I thinned it a lot and it's quite translucent now) and while it's not as bad as "enamel over rubber" which will rub right off on your fingers even after months, it is still "tacky" after a couple weeks. It's not going to rub off, but it does lose its gloss after repeated handling, and kinda attracts dust etc. I can't figure out why some areas dried and some didn't, it doesn't seem directly related to what was underneath the paint.

Stripping/repainting is NOT an option. I can either just leave it alone, or add something to it.

Should I just let it dry for like, a year, and hope it'll fully harden some day? Could I put a clearcoat over it and hope the clearcoat dries hard? Would said clearcoat screw up the underlying layer?

[Maxtype]

David, my gut feeling is to leave it alone for a few months, and then get a glosscoat on it. I'm hoping it'll "harden".

Maybe the others will have a better thought.

[nightmareB4macross]

Hey David,

Your question is a bit vague. Maybe if you were to specify what type of paint was used, other than "cheap craft paint", and what it was applied to, it might be easier to help you out.

Did you use a primer prior to applying the "cheap craft paint" ? What type?

NB4M

[jardann]

Yeah, a few more details might help. What did you thin it with? What material is it painted on to? I would worry about putting a clear coat over it at this time. With an acrylic clear coat you would risk it fogging up or not curing as well. With an enamel clear coat you would have a very good chance of it cracking if it cures first and then the underlying color continues to cure at a different rate.

I think I would put it in a safe, dust free place (covered if possible) for a good long while (months?) before trying anything else. You really want that color coat to have as much time to harden up as possible before putting anything on top of it.

How heat resistant is the item? You may be able to speed up the cure of the paint by gently heating it. Using a hair dryer maybe, or placing it close to an incandescent light bulb etc. Be careful to avoid blistering the paint or damaging the item. Just an idea that would have to be handled very carefully if tried.

I hope you can come to a good solution. Good luck!

[Greyryder]

My mom has done One Stroke painting on glass with that type of paint. It takes 28 days to fully cure. I think hers might be a different brand, since I've never known it to stay tacky for so long. Might just have to give it a couple more weeks, or you may have to find a suitable clear coat.

[David Hingtgen]

OK, exact specifics:

Paint:

Apple Barrel Gloss "Real Green"

Thinned (quite a bit) with MM acryl thinner (seemed to work well, and the water in this town is often so bad it's cloudy, so I never thin with water)

Added a bit of Liquitex Flo-Aid

Added a touch of black (I honestly don't remember which, had to be either Testors Acryl or Pollyscale Acrylic--which are nigh-identical formulas)

Applied over:

Blackened metal (likely plated brass), bare steel wire, bare plastic, factory-painted plastic. It's a model locomotive, so I honestly don't know what the exact plastic or paint is. Factory paint is very durable and very glossy though, I can tell you that. Plastic is likely styrene, a fairly hard formulation.

No primer, as frankly that would have added yet more layers and it was hard enough to paint the little details. (does anyone ever brush-paint primer prior to painting small details etc?)

I have noticed/discovered that while it has dried "2nd-least-tacky" on the metal parts (railings/piping---fine steel wire mostly), it really hasn't adhered to the metal at all--it's really just a coating, adhering to itself 360 around the wire.

It has totally dried on the areas where it was applied over bare plastic, factory green paint or factory black paint, but is slightly tacky where it was applied over factory silver paint.

However, where it was applied over factory green paint, where the factory paint was applied over "not so hard" plastic(PE?)--it's very tacky.

[PetarB]

David I can tell you one thing as a fact - do not clearcoat it while at all 'tacky'. You will regret it later, it will discolour/flake/turn into viscous radiactive bubbly goo!

I'm going to guess that the plastic where it's not dried over properly is something like polyethylene, although I could be wrong.

Next time... a light pass of metal primer (Tamiya make a great one). Or - you guessed it - "avoid the cheap stuff" altogether, as my father in-law used to tell me!

I don't see a way out other than strip and start again. The only other advice has already been given - wait it out and see...

Best of luck, I feel your pain! It's an annoying situation!

Edit: yes I airbrush thinned primer on tiny detailed parts. Thinned Mr Surfacer is good!

Edited April 30, 2010 by PetarB

[hibiki_konzake]

if you want to mix paint with water use demineralized water or something similar. my dad is a pro spray painter and he told me paint will become bad if you mix it with tap water.

his exact words were that the paint becomes moldy

Edited April 30, 2010 by hibiki_konzake

[MechTech]

The flo aid and thinning will delay the curing time of the paint. If you can let it sit in some sun (without getting hot) that may help (as long as there's nothing to yellow. I hate using gloss enamels for the same reason. I think as was said, just let it sit. If you have a dehydrator (like for beef jerky and fruits), that may suck some more moisture out too. If it's humid where your at (house conditions) that may be an issue too. Happy drying! - MT

[David Hingtgen]

Currently I'm just continuing to let things sit. (actually stripped and repainted one small part that I was able, but only because the paint got a nick in it---uncured paint isn't very durable) Maybe another month will do something, but I'm thinking more like 2 or 3 months for noticeable improvement, if any will occur. (I'm pretty sure some segments have dried for over a month now)

I could use a hair dryer or something and heat it up a little, but I doubt "30 secs of being warm" would do more than "3 weeks of being room temp". Can't get it hot, some parts of it are the type of plastic that'll "curl" when hot, and never un-curl. (and I don't plant to experiment/test and find out too late that a "safe" part wasn't)

On a related note of a different paint---should I put a clearcoat over an acrylic paint that dries, but instantly liquifies upon contact with water? Very strange--a general rule of acrylics is that "contact with their thinners will not reliquify them"---especially when their thinner is pure water. But this one---contact with almost any moisture (other paints, saliva, etc) will make the paint just come right off. I'm hoping a lacquer clear from Tamiya would be non-aqueous enough to not affect it.

[Noyhauser]

Currently I'm just continuing to let things sit. (actually stripped and repainted one small part that I was able, but only because the paint got a nick in it---uncured paint isn't very durable) Maybe another month will do something, but I'm thinking more like 2 or 3 months for noticeable improvement, if any will occur. (I'm pretty sure some segments have dried for over a month now)

I could use a hair dryer or something and heat it up a little, but I doubt "30 secs of being warm" would do more than "3 weeks of being room temp". Can't get it hot, some parts of it are the type of plastic that'll "curl" when hot, and never un-curl. (and I don't plant to experiment/test and find out too late that a "safe" part wasn't)

While I hope it does work out, I've been in your situation before with generic paints and its not been a successful one. If its not dried in a month, then its unlikely to dry (and more likely to get worse as its a chemical reaction between the paint and something underneath.)

On a related note of a different paint---should I put a clearcoat over an acrylic paint that dries, but instantly liquifies upon contact with water? Very strange--a general rule of acrylics is that "contact with their thinners will not reliquify them"---especially when their thinner is pure water. But this one---contact with almost any moisture (other paints, saliva, etc) will make the paint just come right off. I'm hoping a lacquer clear from Tamiya would be non-aqueous enough to not affect it.

There are two parts to your question. Some Acrylic thinners will react to dried paint: windex or alcohol being the top two. Water should not and I've never seen what you're describing for dried paints. I've found that future does react to dried paints, albeit minimally. It may also be due to the fact that it wasn't completely dry. Consequently, I'd be very careful in applying a glosscoat to it. However if you're using a lacquer glosscoat like Tamiya I'm almost sure you're going to get a reaction, as lacquers will eat into any acrylics faster than it can dry. If you try to brush it on it will streak the colours, while airbrush will leach the colors over the surface. There are airbrush techniques that might be able to mitigate this. I personally use Modelmasters acryl glosscoat for a first glosscoat because its generally non-reactive and dries really fast (30 minutes versus 24 hours for future.) It has orangepeel problems, but it lays a good, thin base, for later gloss coats of future.

The best might be to do a test piece with the paint on a piece of scrap styrene, wait a week, test the paints durability (in regards to reactivity to water) and then spray on lacquer and other glosses you might have. That will give you an idea of where to go.

[kanata67]

hey dave... been a bit.

There are a couple things you can do to speed the curing process without risk. Much like drying fungus you can put said model in a box in a closet and throw a bunch of "dessicant" packets in with it. You know the little packets of silica+ stuff they put in electronics and other boxes that say "do not eat". Better still, if an option, is if you have central heat and ac place the subject on a piece of cardboard underneath the intake for the air handler [usually in a closet somewhere in the house]. only do this if your ac unit does not have a leak/drip. The constant airflow devoid of moisture works wonders drying fungus... I mean paint

when absolutely dry I still recommend citadel clear coat sealer applied as directed. You will probably have to order a can but I've used the stuff on everything from models to my old car.