Weirdest Paint Issue I've seen

[binaryterror]

Now I've been in RC since the late 80's and have painted numerous bodies with the old Pactra Cans, sure I've done dumb things and hit issues, but this recent one has me completely boggled.

I'm painting a Wraith Kit, mainly the interior first. Completely wash the body in soap and water and let air dry in the office. So I grab a brand new can of Pactra Indy Silver, shake it for 2 minutes or so and have it stored in 70* office at work. I take the 2 interior pieces to the warehouse area and spray them with a decently heavy coat (nothing too think and no runs or drips and did need a second coat to get coverage). It was left to dry in the warehouse, temp was 65*. Now I come in this morning and the paint has cracked pretty badly and in the corners it has pulled away from the body and made what looks like a caulk grove but the paint doesn't touch the lexan underneath. Both coats cracked.

Could it be a bad can of paint? Too cold of temps (I've painted in colder weather before)? Maybe I need super thin dusting coats?

Now I have to search and find a way to remove the Pactra and retry, but I do not want to start painting the body panels until I learn what I might have done wrong.

Only thing I didn't do that I normally do is instead of washing with soap and water, I usually use rubbing alcohol to clean the inside.

[bigstu]

This sounds excatly like what I saw the last two times I used some Pactra paint. Both times I painted a short course body first one straight indy silver the second was the rust metallic color, I think it is sunburst. Light coat, dry time, med coat, next morning, cracks everywhere. Both times I washed the body with soap and water, even scuffed the insides a little bit to promote adhesion. Used the body and in no time the paint was flaking off.

The only thing I could come up with, both times I painted the bodies in my garage, and then moved them in the house to dry (in the basement to be specific). I think the change in temperature is what did it to me. Not 100% sure though.
The solvents flash off so fast, the paint sets up really quick and next thing you know, you have hard paint that is trying to stick to a body that is changing size. That is my only guess.

I emailed Testors, and they said it sounded like a contamination problem.

For removing the paint, the only thing I know is DOT 4 brake fluid. Let it soak and be preparred for some clean up.
Lately, I've been using the Krylon Fusion with good results. Not a lot of great colors, but I mostly use it to back the water based paints I use.
For the paints I airbrush, I have used a variety of materials, mostly Fastkolor.. But I have always backed it up with the Krylon Fusion and have had great results.

[binaryterror]

Well damn, that's exactly what I'm seeing. Maybe its time to switch to Tamiya Acrylic colors again like I used to use.

Thanks for the tips.

[STANG KILLA SS]

i had that pulling away in the corners happen to me using house of color pearl paints that were supposably for lexan.
also. you need to always mist on the first two coats when painting lexan. youll get alot better adhesion. then lay it on thick.
and also yes, you dont want the body changing temps whille painting. ie stored in your house at 74* and then going outside to paint and its 100*
or winter time is worse were its colder outside, because the compressed paint is already chilling the body quite a bit.

[HARDKNOCKZ]

Originally Posted by STANG KILLA SS

i had that pulling away in the corners happen to me using house of color pearl paints that were supposably for lexan.
also. you need to always mist on the first two coats when painting lexan. youll get alot better adhesion. then lay it on thick.
and also yes, you dont want the body changing temps whille painting. ie stored in your house at 74* and then going outside to paint and its 100*
or winter time is worse were its colder outside, because the compressed paint is already chilling the body quite a bit.

I've used HOK for over 20 years & haven't seen anything listed fro lexan. I'm curious. Unless you mean that model paint they made Kustom Kolors?

Anyhoo...what you guys are experiencing is pretty common in solvent based paints. Solvents carry the colors & when those solvents get trapped behind dry or drying paint, the wrinkle the surface trying to escape. In kustom paint we have a few terms for it like solvent pop.

When you lay a heavy coat down, you have to make VERY sure that the temp is as low as possible so that the paint doesn't dry from the outside in. In urethanes, we control this by different reducers...some are slower for high temp painting.

Your best bet is to lay multiple, LIGHT coats letting each FULLY dry before spraying the next. I'm sure in your 20 plus years of RC you have sprayed lids like this one & gotten away with it but as you've seen...it only takes one time to ruin your day. It IS possible that Pactra has changed their reducers too. If they went to a faster reducer...its more important than ever to apply light, even coats vs heavy.

Hope that helps.

J.D.

[bigstu]

I think Hardknockz is right. I think they changed the reducer.
It smells different when sprayed now.
And now that you mention it, I don't ever remember spraying it and having coats dry to the touch so fast.

One of the tricks I have always used is to drop the can in hot water, from the faucet, and let it sit for a few minutes.
Has always seemed to raise the can pressure just a little and it sprayed much smoother.
I wonder if that is causing the reducer to flash off on the outer layer first, and this is causing the problems we are seeing.
I just did a body for the new comp truck, sprayed my water paint, in multiple coats, and then backed it with a medium coat of Krylon Fusion.
The paint was dry to touch in less than a half hour. No wrinkling, but I painted it in the basement and let it stay there to dry.

[STANG KILLA SS]

Originally Posted by HARDKNOCKZ

I've used HOK for over 20 years & haven't seen anything listed fro lexan. I'm curious. Unless you mean that model paint they made Kustom Kolors?

Anyhoo...what you guys are experiencing is pretty common in solvent based paints. Solvents carry the colors & when those solvents get trapped behind dry or drying paint, the wrinkle the surface trying to escape. In kustom paint we have a few terms for it like solvent pop.

When you lay a heavy coat down, you have to make VERY sure that the temp is as low as possible so that the paint doesn't dry from the outside in. In urethanes, we control this by different reducers...some are slower for high temp painting.

Your best bet is to lay multiple, LIGHT coats letting each FULLY dry before spraying the next. I'm sure in your 20 plus years of RC you have sprayed lids like this one & gotten away with it but as you've seen...it only takes one time to ruin your day. It IS possible that Pactra has changed their reducers too. If they went to a faster reducer...its more important than ever to apply light, even coats vs heavy.

Hope that helps.

J.D.

yes the kustom kolors, it was listed as usable for lexan.