Enamel paint problem

[GrenadeKing]

I'm working on a recreation of a vintage rifle. The stocks on this gun were brown plastic painted green. The closest match to this green that I could find off the shelf, was a can of Testor's Model Masters enamel.

The problem is, the paint doesn't seem to be setting up. It's been 4 days and it's still rather soft. It's dry to the touch but, it scratches off easily, it has no durability.

The real problem, is that the over spray on my table outside, that's been in 90+ degree heat with an absurd amount of humidity, for the same amount of time... is solid as a rock. I have to put major effort into scratching it just to break the surface of the paint.

I'm wondering if by leaving it in the house, I'm slowing the cure time. Or it maybe I just did something wrong and need to strip it off and do it again.

I'd really hate to try and strip it as I have 3 other coats of paint under it and I can't use sandpaper because there is too much detail to the surface piece.

Should I just leave it for a few more days and hope for the best? :confused

 

[robn1]

Heat does speed up the hardening process. My Dad once recommended placing painted items under an overturned box with a light bulb inside.

I've been using Rustoleum oil based enamels, combined with a hardening agent. It works great, it used to take this paint months to harden, now it sets up rock hard overnight. I don't know if the hardener will work with Testors, but if it's oil based it should. The hardener I use is from Valspar, I've only seen it in Tractor Supply stores.

 

[DL 44 Blaster]

If you applied a second coat too soon or one heavy coat it will take a long time to cure since it's really too late for it to "dry". If you did wait plenty of time inbetween coats the surface that was painted onto could have contamination on it such as oil, or some other residue which is preventing the paint from fully drying.

 

[GrenadeKing]

I cleaned the surface with alcohol before spraying. I did spray quite a heavy coat though... I'm just wondering why the overspray outside (which has all the same layers of paint) is solid and more or less unscratchable but, the actual piece that I've had inside, isn't.

It's dry to the touch, you can handle it fine, it's just "soft". Peels off with fingernail pressue.

I do have a mini-heater that gets up to about 90, I suppose I could sit it infront of that for a little bit and see if it helps any.

I really want to try and tackle the problem now because, I have 3 large parts to paint this same color.

 

[DL 44 Blaster]

It sounds like the coat might have been too heavy since if you prepped with alcohol your surface should have been clean and ready to accept a paintjob. The only explanation I can give as to the overspray drying is that it is likely on a paper / cardboard or some other porous material letting the moisture wick out of the paint, into the surface material thus drying completely and much faster. With the plastic being coated so heavy the moisture has no where to go so it's trapped between the plastic under-surface and the air. I would assume it will dry fine, but make take upwards of a month confused as now it has to "cure" rather than just plain old "dry". If you need to and you test a spot first, you could use a stripper to take off the paint and re-shoot it, as long as the rifle isn't made from styrene.

Don't feel so bad...I just spent the better of three days a month ago repainting the entire front clip of my black '97 Grand Prix. My wife had nailed it a couple of years ago with our other new car...brilliant I thought. :rolleyes I had done some surface prep with glazing compound, sand, prime, paint x 3 coats, clear x 3 coats, polishing compound, polish x 3, then wax. It looked like glass............and today when pulling it out of the garage, which I keep it backed in and pulled all the way over to the left of the garage (passenger side faces the wall) since it's the third car, I accidentally scraped it onto the garage door roller frame. Two huuuge gouges and scraped a crapload of paint off. All my work ruined. It looked like heck for two years and one month after I fixed everything, I ruined it. So now I've sanded, prepped, and hit the area with more glazing compound. Tomorrow is a full day of sanding, priming, masking, car covering, hopefully painting, and clear will get done if I bust arse.

A hobbists' work is never done:cool

 

[GrenadeKing]

Ouch. I know what that's like. I painted a guitar awhile ago. Lots of prep, then paint, then wait, prep, paint... then catasrophic failure, repeat above steps with crossed fingers, etc. :lol


This is my first time using this specific brand of enamel for something like this. For several reasons, I sprayed this small part first, partly because I needed to do another layer of a different color on the other parts and partly as a test.

If I do decide to strip it, is there any enamel specific paint remover that's pretty good? I've heard I can use oven cleaner but, I'm a little leery about that and how it may effect the other coats. The plastic should be fine, it's actually a form of bakelite so, should be fairly chemical resistant.

 

[DL 44 Blaster]

I have heard the oven cleaner route to stripping as well, but never tested it. I have used plain old "paint stripper" , but it too can be catastrophic to certain plastics, such as styrene. Some plastics it has absolutely no effect on......I've had good luck with it, but one bad when I used it on styrene. My own dumb fault really.

I might just try plain old mineral spirits/paint thinner to clean off the heavy coat if you don't seen any improvement, or don't want to wait until it fully cures, if it ever does.

On a side note, I have all of the sanding done, two coats of primer, three coats of paint on my car and am waiting to do the clear. I decided solely to paint this car today since the weather men up until this morning said that the humidity was going to really be low today....NOT...it's been overcast all day and humidity around 50%:angry Now after lunch it's gotten to near 60%:angry I swear the weather forcasters can't even predict friggin' humidity.

 

[GrenadeKing]

Not much choice on the humidity here. It's always high. :wacko It's either paint and hope it works or never paint.

I sat the part infront of a small heater/blower for about an hour the other night and that seems to have done the trick, or at least kick started the curing to a point where it's more "safe" to handle. It passes the fingernail test for the most part so, it should get better with age now.

I went ahead and sprayed one of the larger parts and, aside from a run, it turned out pretty good. I'll see if I can't polish it out and then give it a second coat after the instructed 48 hour wait. Lucky for me, enamel seems to be self leveling to an extent.

 

[DL 44 Blaster]

That's great about the heater helping speed it along. Maybe a couple of more "sessions" in front of it would really do the trick at curing it quickly.

I hope the rest of the project goes smooooth. :thumbsup