time for clear coating

barto

Gravity Guru
I read everywhere that if I want to put a clear coat over utrethane paint, I have to do this in a few hours before the urethane paint becomes too dry. Otherwise there will be no chemical reaction between coats, what causes poor clear coat adhesion.
I also read that acrylic paint has no time limitations for clear coating, and I can put the CC over it whenever I want to.
However, there will be no chemical reaction between acrylic and clear coat (or indeed?) as well as overdried urethane! So what's the difference?
I'm using PPG urethane colors at the moment and I'm worried about poor CC adhesion in the future, because my airbrush painting process takes time and the clear coat is applied in a third party workshop (more time lost).
I'am at very begining, and wondering which way to chose. What is you experience in terms of automotive painting? Is the time issue important in airbrushing? How to solve it if it really is?
 
As I remember, you can do it more than in few hours concerning even applying your clear over urethane basecoat. Time window before clearcoating is bigger, check the manufacturers' data.

While airbrushing people work with the urethanes over week, then clearcoat the work and everything goes OK. Surely, the surface before ABing must be properly sanded and degreased and degreased after work before the clear, but being very careful on the airbrushed part for not to spoil the work. Some people also apply a light coat of the binder (transparent basecoat, any paint line has it) over the artwork for adhesion purposes.
 
I read everywhere that if I want to put a clear coat over utrethane paint, I have to do this in a few hours before the urethane paint becomes too dry. Otherwise there will be no chemical reaction between coats, what causes poor clear coat adhesion.
I also read that acrylic paint has no time limitations for clear coating, and I can put the CC over it whenever I want to.
However, there will be no chemical reaction between acrylic and clear coat (or indeed?) as well as overdried urethane! So what's the difference?
I'm using PPG urethane colors at the moment and I'm worried about poor CC adhesion in the future, because my airbrush painting process takes time and the clear coat is applied in a third party workshop (more time lost).
I'am at very begining, and wondering which way to chose. What is you experience in terms of automotive painting? Is the time issue important in airbrushing? How to solve it if it really is?
I work in a body shop, and worked at a sign/ scenic art company before that, boat company ,then military body work before that
I've had a lot of experience with different paint situations, substrates and combinations.
The solvents in clear will soften and bond to the waterbornes at any time.
For urethanes, look at the TDS.
Some have open times up to 7 days, some are 24 hours. Some depend on what additives are used.
If it's unclear, contact the supplier or company, they may have additives that extend the open times even if that is not their intended purpose.
It's different for every paint.
What ppg base are you using?
 
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I work in a body shop, and worked at a sign/ scenic art company before that, boat company ,then military body work before that
I've had a lot of experience with different paint situations, substrates and combinations.
The solvents in clear will soften and bond to the waterbornes at any time.
For urethanes, look at the TDS.
Some have open times up to 7 days, some are 24 hours. Some depend on what additives are used.
If it's unclear, contact the supplier or company, they may have additives that extend the open times even if that is not their intended purpose.
It's different for every paint.
What ppg base are you using?

I don't know which PPG product it is, I buy it from the local airbrush retailer under his own trademark. All I know it's from PPG.
Should I focus on a paint specification or clear coat specification? Which one is more important here?
The paint I guess.
 
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I don't know which PPG product it is, I buy it from the local airbrush retailer under his own trademark. All I know it's from PPG.
Should I focus on a paint specification or clear coat specification? Which one is more important here?
The paint I guess.

More likely you use the colours from PPG Deltron line, that guys pouring for you in smaller cups from the mix stand.
PPG basecoats are great for airbrushing, if you can afford them, you need nothing more. Generally, many of the basecoats are good for airbrushing.
Use HS or UHS clears from PPG and you'll have complete compatibility of the products with great result.
 
I don't know which PPG product it is, I buy it from the local airbrush retailer under his own trademark. All I know it's from PPG.
Should I focus on a paint specification or clear coat specification? Which one is more important here?
The paint I guess.
You'll have to find out.
Deltron and Omni say 24 hours. But pushing 36 is probably not an issue.
Dupont nasons says if you use activator in the base than it can be cleared anytime..... Probably will be a question for ppg, or whatever subsidiary it is, but only when you know what product it is.
Ppg makes about a zillion other brands too...so saying it's from ppg doesn't necessarily tell you much.
The guy you buy it from should know...since he's selling it to do graphics it would be kinda dumb not to know the max time to clear.
Keep in mind you're not doing a full coverage solid color on a panel though
So unofficially.....pshh whatever.
Start w blending clear 2 weeks later and call it good.
 
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Either way, let be honest, how many 20-30 yr old custom jobs are running around....it's not scratch repair on a lambo, anything I would even remotely consider using createx for (1/2 Step above craft paint) I wouldn't be worried about open time on graphics. I still tried to answer the actual question as it was posed though.
 
https://www.google.com/url?sa=t&sou...FjAAegQIBBAB&usg=AOvVaw0VLEFkTjfyjU4urgGGpNDU

Looks like the current one just expects you to activate....just says recoat anytime

o_OIt's smth new! For what I knew till now was either 1K basecoats that must be clearcoated and one stage 2K paint system (paint+activator). People don't use those 2K paints for making the artworks as activated paint has short lifetime.

Indeed, from the link I can see activated basecoat that must be clearcoated. Personally, I wouldn't use this paint for airbrushing.
 
Your happy medium would be to just mix a little 4004 and 4030 and go over it during the open time..... Then it can technically get it's clear anytime you want.
 
o_OIt's smth new! For what I knew till now was either 1K basecoats that must be clearcoated and one stage 2K paint system (paint+activator). People don't use those 2K paints for making the artworks as activated paint has short lifetime.

Indeed, from the link I can see activated basecoat that must be clearcoated. Personally, I wouldn't use this paint for airbrushing.
It's wierd, activator in the base doesn't actually cross link it unless it's specically a 2k base coat that must be activated. It just adds iso to it for adhesion.
Still has as long a pot life as any deltron....which has an optional activator too, but idk if it extends open time like w nasons
I've airbrushed with it. I don't think I ever come close to leaving paint in the cup for four hours.
 
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I
Acrylic intercoat over urethane base, than clear coat. Good idea. I wonder if anyone has tried this?
Its an idea, I haven't tried it. I personally don't like the way wicked lays down or know whether it would actually be more durable than just clearing over base that's past it's open time. By the books it would be correct though.
Probably be ok as long as you did it light enough....it'd really just be a holdover tack coat. No reason it shouldn't work as well as clearing over wicked.
 
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o_OIt's smth new! For what I knew till now was either 1K basecoats that must be clearcoated and one stage 2K paint system (paint+activator). People don't use those 2K paints for making the artworks as activated paint has short lifetime.

Indeed, from the link I can see activated basecoat that must be clearcoated. Personally, I wouldn't use this paint for airbrushing.
If you really wanna see some confusion, have a look at vibrance or one of the other systems where color alone is two or three stages ..balancer, binder.. orientation coats etc.... Gets really crazy.... I often spend more time figuring out what I'm supposed to be doing than actually doing it.
 
Today i received interesting info from my retailer: there is no time limit for clear coat since clear has solvent that activates dry paint anyway, and also I can put a drop of a solvent on a dry paint to see it dissolves.
I'm confused, but I have to say this man is probably the best airbrush painter in my country. I have a huge respect for him.
 
Even cured 1k base won't resist solvents.
But if the guy says clear anytime then I wouldn t worry about it.
Whether it's technically correct or not, not likely to cause issues.
 
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