I just bought a bunch of House of Kolor urethanes to airbrush my Stang with but I've never used HOK before. I was told at the paint store that you have to clearcoat the AB work in under 10 or 12 hours or you'll have adhesion problems. I've used PPG urethanes and a couple of others but this is a pretty big project involving the hood and both sides of the car. I really am not looking forward to being forced to do ALL the AB work at once to avoid any problems. I will if there is no other way but I'd prefer to take my time with the airbrushing. Just wondering if any experienced HOK users have any suggestions, tips, caveats or whatever.
Posted by Frank Magoo (Member # 3950) on :
(disclaimer) As this is the internet and EVERYTHING said here is public information forever, I'll keep it PC...
Mr. Jackson;
Take HOK back to store, get refund, go to DuPont dealer and invest in DuPonts Hot Hues, they have candies, pearls, regular opague basecoat colors, a complete system...very clean candies,(similiar to toners of the 50's), also get some HHM-6222; it's a intercoat adhesion promoter...use it to intermix your candies, pearls and such, when done, apply 2-5 coats (best thing about 6222 is it's ability to be stacked, put down as much as you want, allowing significant time between coats to flash off, don't bog it on) over work to protect it,(a fixative if you will)...when ready to paint over that area again, scuff it w/scotchbrite pad, and it's ready for more paint, like urethane clear....(some sand, not scuff, but remember, basecoats are thin, they sand very fast, be consious(sp) of that any time you sand)
I'd spend some time a w/qualified DuPont dealer and learn the Hot Hues system, beats the others hands down, they listened and acted accordingly, resulting in producing the finest system for custom paint on the market today and trust me, I've used plenty of the other guys, er, ahem, products and suffered,er, experienced their customer service policies...
DuPont: HANDS DOWN, THE BEST TODAY !!!
(I don't use their clears as I discovered a damn good one years ago and as it's been said, "old habits die hard", it isn't broke, I'm not fixing it)
Posted by bruce ward (Member # 1289) on :
you also have a great line of HOK duplicates from PPG jobber. less expensive and look the same, I cannot recall the name right now.
as far as the coating time for the candies. that is a recommended time for the chemical reaction to take place. any time after that is a mechanical and may have to be scuffed up.
back when I airbrushed we did letting in HOK and would clear a few days later.
Posted by Joey Madden (Member # 1192) on :
Ricky, actually the 10-12 hour window get opened further when the paint is cleared then colorsanded as with the same as any other paint. What I'm saying is first the base then the color then the clearcoat after which when dried colorsand, this opens the window further and allows any and all artwork for whatever time is needed. If over the airbrushed artwork you want to add pinstripes then the artwork must be cleared and colorsanded so in case a mistake is made, reducer can be used safely without interferring with the artwork. Colorsanding the clearcoat opens the window for further usage. In the past I've had sheetmetal for weeks ready for artwork with no adhesion problems.
Call me if you need support
Posted by Len Mort (Member # 7030) on :
With all urethanes today after twelve hours or so you must scuff slightly, then you may apply top coats or second colors, any time before that is no problem.
One alternative is to add a few drops of the proper hardner to the medium that you are to airbrush with (be sure to clean your applicator immediately) when dry you may scuff with a scotchbrite pad and clear. You can use One Shot with hardner for your air brush work, with hardner and clear with Dupont, Sherwin Williams or any other automotive urethane finish.
If in doubt check with your auto body paint supplier.
Posted by Ian Stewart-Koster (Member # 3500) on :
Yes, Ricky, the available timeframe for repaint is called a 'window'. That ensures that subsequent coats don't just dry & sit there, but actually chemically bond to what's underneath. Others here know waaay more than me on this. An intercoat clear can help, but it'll need rescuffing later, but Joey's solution sounds better than all other options when you want to take your time on the job.
Posted by Ricky Jackson (Member # 5082) on :
Frank I should have gone with the DuPont; I had no idea HOK stuff was so expensive. I have two *small* boxes of paints and reducers and it was over $2,000.00! $80 for a gallon of "paint thinner"? C'mon, gimme a break! I said that I wasn't going to cut any corners (cost) on my project car and I'll probably stick with the HOK for now. I'm not used to feeling like I've been robbed but, at this point, I do.
Joey, what the heck is colorsanding? Also, if I shoot some intercoat clear over the airbrush work can I scuff that with a Scotchbrite later and still get good adhesion or would it be best to use the top coat clear? Can that be done at all?
Thanks guys for your input; I knew I could count on you. Posted by Gavin Chachere (Member # 1443) on :
Do not use the intercoat clear. Intercoat clear is non catalyzed and you dont want a non catalyzed product inbetween a bunch of catalyzed layers. Its only use would be if youre going to go beyond the 10-12hrs recoat time or youre going on top of artwork that may be so detailed that you could damage it by working right on it. If thats going to be the case,use the topcoat clear you bought and you could let it sit indefinitely till you felt like working on it again,simply scuff and start where you left off. The intercoat stuff cant be left under any type exposure either. The stuff Frank is telling you about is different than just plain intercoat clear and works pretty good,only reason i would still advise to stay away form it is that it sounds like you havent fooled with it as much and its easier to make a mistake there with that than with a catalyzed layer over it. Dont scuff any noncatalyzed intercoat clear in your humidity. By colorsanding he means lightly wetsanding the color coat you put down to 'break open' the outermost layer that has started to faux set up,basecoats like that depend on a small amount of physical adhesion at the surface to allow the catalyzed layer to penetrate,crosslink and form one layer,take care to go lightly enuffnot to erase what you did.....its also done between multiple coats of the same color to give you a very smooth coninous surface. A scotchbrite,even the gray or blue may be far to rough and thecost of some wet or dry sandpaper is negligible. After about 12hrs or so depending on enviroment,to simplify things it can start to 'skin' over and you wont get the bonding you need. Under no circumstances add catalyst to the urethane basecoat if you dont want a disaster
Posted by Kurt Silva (Member # 257) on :
Most all paint manufacturers will give you that 12 hr window stuff. It has more to do with the risk of contamination than anything. The only time it might be an issue is if you are catalyzing the base-coats which is not neccessary. Uncatalyzed bases will soften and absorbe the solvents in the clear and adhere just fine. If you are concerned, HOK intercoat clear is an option. That is what it is designed for. If you have to stop in the middle of the project and can't get back to it for several days the intercoat clear will protect it. Just don't put it on to heavy and lightly scotchbrite it before you start airbrushing again.
Posted by Ricky Jackson (Member # 5082) on :
Thanks guys. I'm not catalyzing the AB colors; don't really see a need for that. I'll do my artwork, shoot a light coat of intercoat clear over it then when I get ready for the painter to clear coat it I'll lightly scuff it with a Scotchbrite pad. I figured that would work; just wanted to be sure.
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