when is high build primer over kill? what to do?

I have all of the major body work done on my car. I need to get another coat of primer on the car to make sure everything is straight. I have already used high build primer once on the car and I’m thinking that another coat of high build maybe over kill. I’m sure like always there’s going to be a spot or two that will need more repair. I’m using kustom shop 2k high build primer and I wanted to know if maybe I can reduce it a little so I can spray it a little thinner somewhere between high build and a sealer. If I sprayed it as a sealer and waited another week or two to paint, can I just scuff with a scotch bright pad and shoot my single stage? The tech sheet only mentions wet on wet when sprayed as a sealer.

 

i would only use it as a wet on wet sealer, my experience with a 2k high build primer is that it never hurts to spray a couple coats.

 

I've already recoated the front half in high build and it was pretty straight. It's just a pain sanding this stuff. Maybe if I can get it to lay down better it wont be so bad.

 

You can reduce it a bit more. As far as the sealer characteristics, they go away if you scuff it. One of the main reasons to seal something is to prevent grain from being raised by the solvents in the base coat. Scuffing it could result in highly visible snding marks in the base coat.

 

Reduce it as much as you see fit, just make sure its not water when you go to spray it!

My advice though is to spray it in high build mode if you think it needs more primer. Might as well get a few extra mils on it to get it razor straight. If you redice it, it may be too thin to get the job done.

Also, don't confuse high build primer for body filler. I've seen guys put on 8 coats of high build out of their 2.2 tip to cover what one coat of filler would've taken care of. Waste of time and materials.

 

there's no such thing as "a coat of primer". you need at least 2 coats and sometimes 3 for the primer to actually do what it's supposed to do, fill sanding scratches from either bondo or a previous wet sanding. by over reducing high build primer your kind of defeating the purpose of the high build, unless your going to do a wet on wet application, or trying to lay the primer out smoother for sanding and even then, you should read the tech sheet to see how much the paint manufactorer says you can reduce it without problems down the road. as far as sanding the primer, that's just part of the job and scuffing it down with a scratch pad is the lazy way out and not sufficiant for good paint adhesion. by trace coating the primer before sanding, you will know if you have enough primer if the trace coat is gone, and you can't see bare metal or bondoed area's or deep scratches. if you can see either or both, you need more primer, if you can't your ready for sealer and paint!

 

The trick with High build primers is to keep the application to 3 coats at a time. I will usually go 3 applications of three coats. Finish the body work with 180 grit sandpaper and get all of your pinholes and sandscratches filled before you prime. Then apply three coats of HB with a 1.4 mm tip on your gun. This way you won't overbuild the surface. Then let the primer dry out. 10 days is good or longer. Then block this out with 180 grit sandpaper to catch any marks and ripples. Now apply three more coats and let it dry out again. 10 more days. Then block out the primer with 240 and 320 grit sandpaper. Now apply 3 last coats reduced 20% and let it dry out, 10 days again. Then finish sand with 400 for single stage, 600 for base and 800 if your going silver and some golds or custom finishes. you'll be surprized how much brighter the silvers and golds are with the finer sanding. (More reflection). This is what works for me.

The Old Tinbasher

 

You guys should try Southern Polyurethanes...............their epoxy primer is top shelf!