Possible Paint crazing???????

[Dublinguy]

Hi all,

Sorry for the vague Subject line but here is my problem. Got started a week or so ago on a Tamiya Monte Carlo impreza. All going well even the body was going ok. I did the usual prep on the body, cleaned it, light sanding, 2 mist coats of Plasti-Kote grey primer, left to dry for about 5 days. Then started with TS-50, again 2 light coats and one heavy coat. Left that to dry but noticed I had a few specks of dust and also some runs in the paint. So sanded all the problems out but on the rear of the body around the bumpers I sanded through the primer. So I did the sensible think and re-primered the whole rear bumper. Now I only left this for about 24 hours to dry before I put one light coat and a slightly heaver coat of TS-50 on. And here is where the problem has started. Im not sure if the paint has just cracked or whether it has crazed. imnot sure what crazed should look like. But on my body it looks like raised cracks.

So my question is if it is crazed, does that generally mean that the plastic is ruined or can I sand the crazing back to a smooth finish and start again with that section of the body? I think the problem occured because I didnt leave the primer to 'gas-out' long enough. My impatience I suppose. The worst thing is I was fairly happy with how things where going up until then.

Any help advice would be appreciated.

Ciaran

[christofurr]

I'm not 100% sure of what your talking about, but I'm sure someone would be.

Have you got any pics of what it looks like? Pictures speak a thousand words .

[Dublinguy]

Hi Chris, thanks for the reply, I'm in work at the mo so unfortuately no pics. I can take some tonight but it will only be with a web cam so i hope the quality is ok.

Ciaran

[Diesel2NR]

the problem might be that the primer had a bad reaction with the tamiya paint. I'd strip the part with brake fluid (make sure you wear chemical resistant gloves) and spray it again with the same amount of paint that you sprayed the body with. That is if it's not an attached bumper. If the bumper is attached though, I'd strip the body and start completely over. Pictures would help though, because I'm not sure exactly what you're talking about.

Edit: Another though would be that the tamiya paint hadn't completely cured before you hit it with the primer, as I think you hinted at.

[chrismcgee]

as for primers i always use a halfords own brand white or grey, its never had any reaction to any of tamiyas paits be they airbrushed acrylics or ts sprays, or anything else for that matter, its an acrylic based compound

just rub it all back down wont take long, then primer with the plasic primer, leave for a few hours, then spray, your not supposed to leave primer to air for too long other wise other conaminents can get to it, always best to spray once it has dried for a few hours

[Dublinguy]

Diesel2NR,

That helps greatly thanks. I think you might be right about the paint not curing properly before I went over it again with the primer. The bumper is attached so if I strip it I hope that I have enough paint left in the can to spray it again. Its only a can of 'mini' TS-50'....I'll still do the pics later but like I said I think your right about the paint not having time to cure because the rest of the body is ok (by my standards), the bonnet, roof and doors are all smooth.

Ciaran

[Martbee]

Happened to me one time... wrong primer and the paint reacted very strongly with this primer... giving the car and old rippling face. Like the ground after an earthquake. So I made a few try on a scrap plastic piece and notice that when I take this primer, it took at least 3 light coat of TS paint before the big one... 1 or 2 isn't enough so maybe it's just what happenned, the rest of the body was shoot with 2 thin layers before the big one and the bumper has only 1 light coat before the big one. So go easy with the 2 or 3 first coat or change primer... the Tamiya fine primer don't react at all with the TS paint no matter how big is your first coat.

[Dublinguy]

Martbee,

LOL another good suggestion, aftert the two coats of primer on the body I used two light/mist coats then a good wet coat. But when I re-primered the bumper i had one light coat and then one heavy coat (not sure what I was thinking doing that). So i guess sand it all back, re-primer if I have too, leave for a few days, a couple of light coats and then a heavier coat. Does this seem good?

Ciaran

[Martbee]

Sound good buddy... let us know if it worked... or not. Hope for you the first option will be the one.

[primera man]

IMO you need to use the same brand of paints and you have to give the paint enough time to gas-out.

You will need to sand back and re-do the area again

[Dublinguy]

Hey all,

Well just to let you all know how I got on. I sanded back the paint and the primer and the Plastic is fine (Thank Jaysus for that!!!!). avent had a chance to re-primer and paint just yet but cetinaly my diagnosis is I didnt leave the primer to gas-out for long enough. I dont think its and actually reaction between primer and paint as the rest of the body is fine. Ah well alls well that ends well. When I have the body painted again I promise to show a quick pic to let you all see how Im getting on.

Thanks for all the suggestions, your all top-class as per usual.

Ciaran

[Murray Kish]

I'm a new guy, but I just read your post and it does sound like the paint reacted with the primer. Crazing is a little different in that the paint actually melts the plastic (not fun). It will look more like lots of shallow grooves in the paint, rather than raised cracks. You'll know it if it happens...

Murray