a paint question

[67hcode]

I'm painting a few bike parts and I'm using basecoat clear coat. I'm still pretty new to base/ clear paints because I haven't done much painting in years. I'm practicing on some of my parts before I paint the charger this spring. Anyway, the guy at the paint shop sold me some ppg base, I think it's dbu  and for clear he sold me some omni mc161 , here's the problem I keep having with it. After spraying the base and clear and wetsanding this fender, I noticed a small spot where I had burned through while wetsanding. I mixed up a bit of clear and tryed to hit the spot with a little color and it caused a big spot to lift on me, kinda like blistered. I ended up sanding down the spot and figured I'd seal it with some primer and spray some color on top of the primer. When I hit the spot with primer, the primer is causing it to lift!  Is this stuff always such a pain in the ass!  I'm about ready to sand the whole thing down to metal and start over with something else!
Any help or advice would really be appreciated.
Thanks,
Bob

[Silver R/T]

You should've used hardener/catalyst

[67hcode]

I did use catalyst.  What im wondering is if all base coat clear coat is so touchy or did they just sell me some cheap crap

[Drop Top]

What did you use for reducer in you base? What sealer did you use to go over it with after you sanded through? PPG's DBU base is some of the best base (if not the best) on the market and has been for a very long time. I don't like the Omni line. Its PPG's line of cheap paint/clear.

When I go through. I mix up some base first shoot the the problem area with the base. Then shoot the entire panel with clear. If you went past the color then you will need to reshoot the sealer. If not don't shoot the sealer. I just fixed a deck lid on Friday like this. It was with PPG's base coat. What I did was after sanding down the deck lid with 400 wet. I shot the PPG base over just the rub through. Then cleared the whole deck lid. I have had this problem using cheaper lines of paint systems. Including Du Pont. But I have never incounterd it with any of PPGs line of paints.

At this point your going to have to start over. The problem is in your base color. Thats why I'd like to know what you reduced your base with and how long you wated between coats. I also need to know the tempeture it was at the time you shot the base and the temp of the reducer. Its reacting like it didn't cure enough between the base and clear. Was the base dry to the touch before you aplied the next coat? How many coats of base did you spray? Was the base dry before you sprayed the clear?

Answer these questions for me and maybe I can help with the next time you shoot it.

[67hcode]

Drop top,
Thanks for the help.  to answer your questions, I reduced the base with drr1170  1.5 1170 to 1 dbu
I usually get the garage up to at least 70 before I spray anything. I waited 10 to 15 min between coats, so i thought it was dry enough. When I first started having trouble was when i tried to spot in a little color on a little spot that had been wetsanded and it seemed like the new base coat worked it's way under the clear and caused it to lift.    i resanded and went over with k36. I had the same problem with this at first too. I then sanded out the spot again and hit it again with k36 but this time i put it on really dry and in several coats.  Someone I had talked to said that if you lay the material on too heavy when you're fixing a spot like this it can cause it to do this. After a few light coats of k36 it looks pretty good..no sign of any kind of reaction. I was planning on blocking the whole fender with 400 grit and then seeing how it takes another coat of color.  Any suggestions?
Thanks again

[Drop Top]

Even though its warm inside the shop. If its cold outside makes a big differance also. I would wate a little longer between coats this time. Maybe 20 min between coats and even 30 before spraying the clear. One thing about PPG's base you can let it set up to 24 hours before you have to sand it. Just mist the coats and dont put it on too heavy at a time. Keep your gun at least 10 inches away from your panel (In this case tank). If your spraying a metalic then you may want to be 12'' away and fog on the last coat. Tack it inbetween coats. This will keep the dirt particals out of the base. I have even sanded the base before putting on the next coat. You just have to be sure its dry enough.

Sounds like you have the problem fixed. You just don't need it to happen again. Just make sure you have all day to do it. Take your time. When its time to clear. Give it the touch test before going with the next coat. Spray a med to light coat first. Then the next coat put it on heaver. The 3rd coat lay it on as heavy as you can. Just be sure you wate long enough betwee coats. Like I said before use the touch test. On the last coat wate a little bit longer after the touch test. But don't wate too long or the clear will lift up and look like a air cleaner finish. Because the under layer will be too dry and it will react with the wet coat. If this happens. You will have to start all over again.