Odd paint bubbling problem

[crawlerpawl]

This problem has me stumped:

I painted the underside of my new lexan body 3 days ago - red first then black. I let the red cure overnight before the black coat and it was fine until today.

Took her out for a muddy trail run and the black paint has bubbled over most of the interior body surface and separated from the red - you can rub it right off with your finger, but the red is still fine. I only noticed the problem after cleaning the mud off with plain tap water. You can see that the red is now lighter everywhere the black has separated from it. I only drove in mud puddles, no salt water and no oily water. Should I have let the red cure longer? It seemed completely dry before I put the black on.

[Headquake]

Hmmm, ive had this problem recently too. I thought mine may be due to the fact i used different brand paint for the red and black. The red coat was tamiya spray, and i have had other problems with tamiya spray chipping off and not really bonding to the lexan well. Not sure what to say.
Hopefully Unglued will pop in, he will sort us out.

[true-scalecrawler]

your not suppose to let the paint cure until your done.......if the paint cures you must sand it in order for it to "stick" 10 min flash dry times are best......also use your judgement.... the key is to not fully dry, but not be "wet" either.... at the middlepoint where the paint goes flat and the whole surface is the same uniform "flatness"



also, if your paint is chipping off, its caused by a heavy finger.... VERY light dust coats(shouldnt even be able to see the first 2 or 3 coats...
if you can paint a body(top and under coat) in 4 coats.... its probably not gunna last....

[MegaToys]

your not suppose to let the paint cure until your done.......if the paint cures you must sand it in order for it to "stick" 10 min flas dry times are best......also use your judgement.... the key is to not fully dry, but not be "wet" either.... at the middlepoint where the paint goes flat and the whole surface is the same uniform "flatness"

yea when i paint i use the same brand paint for all colors and i only let the paint sit for 10-15 mins before i got for another coat or color

[crawlerpawl]

Then my mistake may have been waiting until the next day to put the black on?

Note that the problem is only with the black - the red is still bonded to the lexan - and that the black is soft and bubbly and I can rub it off with my finger. It also took 3 days for the problem to surface.

[true-scalecrawler]

most likley, but if you got a pic of it to post lets see it.....maybe somethin else

[imthatguy]

Were you painting indoors or outside?

[crawlerpawl]

Here's a shot of the black where I rubbed some bubbles off:



And here you can see lighter areas where the black paint separated from the red - it's a little fuzzy but you can see it:




And if that wasn't enough, this morning the black paint has hardened back up and the bubbles are mostly gone, although there's still a couple spots where the bond is lost as shown in the pics above. Yesterday there were bubbles all over the underside covering about half the surface area - looked like it had some horrible disease.

It'll be interesting to see what happens on my next wet trail run. I think I'll keep her dry for a while though.

[UNGLEWD]

Sounds bizzare, doesn't sound like you've done anything wrong.
- used all tamiya, did you blend PS & TS sprays?
Sounds like the red adhered okay, probably lighter because it's showing light through where there's now no black backer
I've seen this happen when people use Tamiya Laquer (TS spray) directly on lexan. I spray TS over top of PS all the time without issue...even after a day....but not the reverse.
- How thick of a coat of black....heavy?

I'm thinking temperature change possibly...Trapped condensation maybe between the black and red?

[true-scalecrawler]

yes..... upon picture review.... i think Kev has your answer there

still hard to say though lol, paint is a fickle thing