i am painting a 70 chevelle shadow gray in PPG DBC 1st time it looked good and i cleared it and i seen blotches so i put 2 coats of clear on and waited a week sanded and resprayed today but i kept the gun about12"+ and it looked ok so i just cleared a 7" spot on the front fender and it looked blotchy again i never had a problem with this before,i am thinking of getting 2 qts of DBC500 SAT MORNINGand use it with 2qts of reduced paint,any ideas i am using sata rp gum with 32psi

HELPPP

When I used to spray Deltron, I used to add 50% clear to the color on golds and silvers to get rid of the blotchiness, I'm guessing the 500 might do the trick.
Spray a wet coat and then go right back over it with a fog coat, usually helps even it out. Some colors are just blotchy no matter what you do, luckily most can't be see outside. Also, sometimes it will even out after the clear starts to dry. 32 LBS. seems a little high with a RP, I spray between 24-27. Good Luck

What clear coat are you using and what is the time frame from last coat of base to first coat of clear?
When I sprayed PPG, I noticed some of the metallic colors would "reflow" when topcoated with clear.
The solvents in the clear would make the metallics move around.
The PPG reps at the regional training site said to extend the flash time(time from last base to first clear)and apply 1 coat of DBC500. The DBC500 helps lock in those metallics from the solvents in the clear. DBC500 acts like a barrier coat.

DBC500 mixes in a 1:1 ratio with DT reducer.

Another thing is what DT reducer are you using with your clear? If your reducer is too cold, it will just kinda stay on the surface, which can add to the "reflow"

Mixing DBC base with DBC500 in a 1:1 ratio will thin down the base, which will help the metallics lay down. But only do this on the last coat or so otherwise you wont get any paint coverage. Mixing the base with DBC500 is for metallic control only...Eric

the clear is a keystone uro-clear,due to retaping for stripes base sits about 4 hrs before clear i am using dt870,i have 4 coats of base on now, in the morning i will go to the paint store and try the dbc 500 with base,i think i have a 24hr window before i would have to sand the base,

After basing with all metallics to be safe. Stand off about 2.5 ft and fog to coats of base, first horizontal and then vertical. Has never let me down. ****es me off to no end having to reshoot.

RandyB..

I had that happen on a bc/cc job I did, turns out I was rubbing too hard with the tack cloth, and left residue behind. Doctor Gun, an amazing paint advice guy for free, who retired, figured it out.

DT870 should not be used for metallics. Try DT885.
870 dries to quickly, not letting the metallics orient. Especially at 12" away.
You can use 870 for solids and clears if you want.
I had the same type problem when I tried cheating and using 870 to get done faster. Went back to 885 and have not had the problem.
I have not needed to do any "fog" coats since the AE days.
Proper gun technique is absolutely critical. 50% overlap and smooth strokes, triggering gun before the panel and letting up after moving past the panel on each stroke.
I don't add any clear or 500 to my base. My concern would be that it would in effect overreduce the color which would cause it to be lighter. I don't know for sure as I haven't tried it.
Most beginners put the base on too heavy, causing streaks, mottling and darker shades. The base itself is not supposed to shine.
I run 28-32 psi at the gun. I use an ADAM guage on my SATA and have checked to see that I have 10 psi at the cap with a SATA aircap guage.
An RP gun will take less, it stands for Reduced Pressure.

you are 1 step ahead of me,i just heard from the ppg rep today and they said to use the dt885 also,i was using dt870,and back off on fliud adj.i was going to just repaint the sides from the top peak down and blend at the roof at the sails ,due to my problems do you think it would be better repaint the whole car a 3rd time,i dont know what is a safe limit so far i have 6 coats of clear and 7 coats of base,but some was sanded off after first paint and 2nd paint and this is were i am at now.
thanks for all the help
Dan