31 replies to this topic

[minidaves]

thats some serious crazing, And i know 1k crazes over time, but never seen anything like that, speak to paint manufacturer is my advice

dave

[Paul Wiginton]

It is because the colour wasnt fully dry before the lacquer went on, the heat from the polishing caused the not fully hardened colour to move.

Paul

[Rulle7]

Newish poster here...
I'm with the above Paul on this one.
Also, waxing a newly painted car is asking for trouble...most professionals would advise to leave the paint several months before polishing and/or waxing to let it all set properly.
Most polishing compounds contain solvents, not something you want to afflict new paint to.
Wax seals off the paint, again not something new paint would be happy with.
Next time, how about leaving a bit more time between coats, also avoiding cold/humid weather during curing time and leave alone for many weeks before applying anything with any solvent content.
Good luck and happy painting!

[minidaves]

had a chat with an old school painter today, his words were paint srinkage due to temp, or base/primer not being fully dry before 1k laquer was applied

[Ste]

Hi all,

After several months of prepping and painting 2nd car with this damned acrylic paint it looks like I've got the same issue again. I'm starting to think that all the hours of hard work just aren't worth it! Could do with some encouragement!

Inbetween putting the 2nd car back together I've stripped the original car back to baremetal and thoroughly cleaned it with panel wipe. Then put several layers of primer on, making sure to let it dry for plenty of time in between coats. Its been flatted a couple of times to get it just right. Now i'm at that scary stage where I've got to apply the paint and I don't want to start without asking if anyone can give me any suggestions of what to do differently this time. If anybody has got any ideas I would be really grateful as I'm desperate to learn how to do this. The only guides I have found are the Haynes bodywork manual and cooper shaz's excellent guide on TMF.

As a re-cap its 1K acrylic laquer in metallic. The general consensus seems that insufficient drying time between coats is the issue, does this change dramatically with temperature?

[imvarma]

You mentioned previously that you were using washing up liquid when flatting, i've not read the whole thread, but this has been known to cause strange reactions with some paints...

[john1.2pearl]

Just out of interest ... what make the acrylic clearcoat your using ?

[Ste]

Just out of interest ... what make the acrylic clearcoat your using ?

The tin says Nexa Autocolor Belco p190-478, it means nothing to me but it was supplied with the paint for both cars so i guess its all thats available.

[john1.2pearl]

Hmmm iv'e been havin the same problems but on a wheel, the make of mine was U-Pol 1k acrylic smart clear which is ready to use, the wheel was sanded with 400 grit paper used dry then a layer HB 1k primer, this was left 24hours to harden then keyed, the basecoat was sprayed in 3 coats, which was thinned with 2k thinners 50/50 and left to flash of inbetween coats for 20 mins leaving 45 mins after the last coat was applied before applying the clear, the clear was applied in 2 coats, 1 semi wet and 1 full wet coat, could it be possible that the 2k thinners in the basecoat isnt compatible with the 1k acrylic clear ?

who knows ? theres a few of us in the same boat by the sounds of things

[Ste]

Hmmm iv'e been havin the same problems but on a wheel, the make of mine was U-Pol 1k acrylic smart clear which is ready to use, the wheel was sanded with 400 grit paper used dry then a layer HB 1k primer, this was left 24hours to harden then keyed, the basecoat was sprayed in 3 coats, which was thinned with 2k thinners 50/50 and left to flash of inbetween coats for 20 mins leaving 45 mins after the last coat was applied before applying the clear, the clear was applied in 2 coats, 1 semi wet and 1 full wet coat, could it be possible that the 2k thinners in the basecoat isnt compatible with the 1k acrylic clear ?

who knows ? theres a few of us in the same boat by the sounds of things

Due to availability issues with thinners at my paint supplier I have used 3 different types, the latest being 2K and the last one was high gloss thinners. I guess thats not the problem. Are you flatting the clear and polishing it afterwards or are the problems apparent straight away?

At one point I made a mess of the first 2 clear coats so flatted a panel and put another coat on top. Immediately it started to crack as I was applying the top coat, I tried to polish it out but it just got deeper over time. I'm starting to suspect the clear coat hates the fairy liquid i use to flat the paint but thats probably just being optimistic! Makes you feel really daft when youv'e done something that even the experts can't figure out!

[john1.2pearl]

Nope, no flatting back for me, straight on with the clear after the basecoat dried and the problem is only appearing a couple of months down tis abit strange

[Ste]

Nope, no flatting back for me, straight on with the clear after the basecoat dried and the problem is only appearing a couple of months down tis abit strange

You would think that the suppliers of paint would be able to assist a bit more wouldn't you? Especially as there are a few of us with this problem as you said. The company I use is very helpful with discount but a bit vague with data and stuff.

[bellicose]

OP, as it won't be an easy fix can i suggest you pull/scrape some paint off the effected panel and try to see which layer the cracks are in. I've got a feeling it will be the clear, i've got no faith in 1K clears as the technology is so old. Also did you use an acrylic laquer colour or a true base coat which requires 2 pack clear over the top.

I've got 27 years experience in the car painting industry and to be honest i've never come across that situation.

[Shifty]

Isn't high gloss thinners for celly?

[Svee]

I see this all the time with newbie custom painters/airbrush artists who ask for help on airbrush forums. Sounds like what we call "crazy paving" in the clear. I get it with some Upol primer i use if i go to heavy too quickly. Does it look like this?...


On this one the reaction didnt show up until 3 weeks later. Until then it looked awesome then this appeared overnight...


The reply from the pro clearcoaters (which im not by the way) is normally one of three things... reaction to something (fairy liquid for instance), going to heavy with your coats or not enough drying time between coats. In my exp its from going too heavy too quickly.

I use Upol 1K acrylic clear all the time (grey and blue tin) and although i mainly spray guitars ive found the best way to do it is to apply a quick dusting coat first to help with adhesion, let that flash off until touch dry then hit it with your wet coats. These are where you lay down enough clear for it to look wet but not enough to run. If you get runs you have gone too heavy. Allow 30 mins between wet coats until touch dry and i normally apply 5 wet coats in total. I find if you lay more than that you start to get issues.
Let those 5 coats cure overnight then flatten back nice and smooth with 1200 wet and dry paper....

Once all the glossy spots are sanded out (its all matt) you can go in with another 5 coats as detailed above. Then let that cure for a good week and then i flatten with 2000 wet and dry paper and finally buff up with some Meguiar's Cut N' Finish. Ive heard rumours of some polishes/waxes causing reactions if the clear is too new so i just stich with the Meguiar's. Does the job fine
That method has worked for me for years and these are the results...




Painting can be a right minefield of trouble sometimes. Some paints dont like some clears, it needs to be done a particular way, not too heavy, not too light, cant be too hot, cant be too cold, no humidity, blah blah blah blah. I have a lot of respect for the bodyshop guys who do this on a daily basis and get great results time after time.
Like i say, im an airbrush guy who sprays guitars mainly, if i was doing cars all the time i would switch to 2K clear but of course there are enviromental issues and health issues to think about when using 2K products. I hope the above helps someone out though

Edited by Svee, 25 September 2010 - 09:02 AM.