paint cracking

[krebs128]

i've been working on my new s2000, i put down 2 coats of testors grey primer and sanded it out-the usual. at least 2 weeks after applying the primer, i put on my first coat of black (ts-14) and a few hours later i came back and the paint was cracked. it was mostly in just one area-the trunk and back bumper, with a few on the front fender and hard top. so i sanded it down, some places down to the plastic making sure of no cracks and applied another coat just a little bit ago, and i can already see cracks forming in the same place. i did a search on this and the only thing that came up was putting down enamel and then acrylic over that would cause cracking, but tamiya paints are resistant to this enemal/acrylic mix crack, or so says their website. any advice on what's going wrong here would help alot, thanks.

[freakray]

I suspect your problem is contained in the first couple of lines of your post, and it originates in paint compatability.
Testors grey primer is an enamel primer, Tamiya TS-14 is a lacquer paint, you should never spray a lacquer over an enamel as the 2 paint types react with each other.

What is written on Tamiya's website pertains to their own paints, they are made to be compatable with each other as far as enamels and acrylics. Tamiya sprays, as lacquers are subject to the same compatability rules though as any other paints, lacquers should not be sprayed over any other type of paint as they will react (hence the cracking).

[krebs128]

oh ok, only compatiable w/ their paints, well that's kinda gay and misleading but oh well...back to sanding. i'll strip the whole car, go buy some testors SP, and hope it all works out good.

my transfer from testors to tamiya (a better paint) isn't starting out too well.

[scaleracecars]

Originally Posted by krebs128

oh ok, only compatiable w/ their paints, well that's kinda gay and misleading but oh well...back to sanding. i'll strip the whole car, go buy some testors SP, and hope it all works out good.

my transfer from testors to tamiya (a better paint) isn't starting out too well.

HMMM,
Maybe you should ask Testors why their paint is not campatable with tamiya paint. The question goes both ways and the superior paint is Tamiya. Also I can almost assure you 100% that the new lacquers are not going to be compatable with the old enamels. You might want to go ahead and ask them now before it actually ships from the factory to the dealers so they reformulate the paint and make an inferior product.
Am I making sense?
You can mix and match different brands of paints as long as they are the same type of paint. No manufacturer is going to place a label on their cans telling you what other brands are compatable with their paints. I superior paint may not be compatable with an old paint.
David

[v3rs3]

hahah, thanks for posting this, b/c I almost did that earlier before I read this post. I was about to primer w/ Testors and paint TS-17. heh

[David_]

i think the enamels can go over the lacquers tho.... not sure how that'll help you,but yea.... lacquer, enamel,acrylic is the order it can go on i think.

[krebs128]

ok, well how should i go about fixing this? i mean, only the back of the car is cracking, but the front is beautiful. i went ahead and sanded it to the plastic in the back, and left the front alone. could i primer the bare spots w/ tamiya primer and then paint again w/ the ts-14? or could i paint over the exsisting ts-14(lacquer) w/ testors primer(enemal) and paint the final color w/ testors black? which would be the best approach.

v3rs3, lol, my misfortune turned out to help you. thanx all for help.