Tiny bubbles in clear coat??? Why???

[big stinkie]

Using PPG StratoClear 2082 with fast activatior on top of PPG DBC. HVLP gun, proper mixing ratios, etc. Spraying clear just like I have for a year now, but suddenly I'm getting real small bubbles deep down in the clear. You can't feel them...they are actually below the surface in the clear itself. The surface buffs up like glass, but when the light hits it they show up like crazy. It looks like the fizz one sees in a freshly poured glass of 7-Up (the Un-Cola,) only smaller. I'm not talking a half dozen bubbles or so, either. There are hundreds and hundreds of the little boogers in there.

The weather here in Kansas is hot now, so I'm wondering if the heat is making the clear set up so quick that the bubbles can't make it to the surface and disappear as they might with a slower dry time.

Any thoughts?

'preciate it...

 

[ezrider]

Big, i believe what you are describing is "Solvient Pop". What this means is that you are putting too much material on too fast and the top is dring faster than what is underneath and solvients are tring to escape, they cant becouse the top is already dry. Those are those tiny little bubbles you are talking about. you also might want to try a slower activator, faster isnt always better especially in the warmer weather. there is no cure for what you have already painted, but next time SLOW DOWN,let each coat flash enough, use the slower activator (i have used Stratoclear with the fastest activator, its too fast change to the medium at least, i perfer the slow ) all you will be changing is the flash time not the dry time. Your clear will also flow better. hope this helped

 

[big stinkie]

Sounds good to me. My mother told me once that I "sew with a hot needle" because I rush everything. As a kid, all my model cars had finger prints in the paint. No patience, I guess. Looks like it has carried over to my adult life as well!

I'll sand the little bubbles out and try the slower activator and I'll spray a coat then leave the shop for 5-10 minutes before I squirt any more. That oughta do it.

"Lord give me patience, but do it RIGHT NOW!"

 

[rex]

Hoser

I haven't used the Stratoclear but I wait 15 minutes and test it with the Concept line.The string test is pretty standard.Touch a masked area and there should be strings of clear between your finger and the masking as you pull your finger away.Then I'll inspect my last coat for any areas I might have gotten heavy or thin on so I don't make it worse and give it a touch extra to flash.Pounding on the coats will also cause shrinkage and dieback.

 

[shaunboy]

ALSO YOU COULD USE A SLOWER THINNER AS WELL
IF YOU BAKE YOUR PAINT AFTER SPRAYING MAKE SURE IT HAS FLASHED OFF BEFORE REACHING BAKE TEMP.
OR ELSE THE TOP WILL DRY REAL FAST ALL OF A SUDDEN AND UNDER NEATH WILL SOLVENT POP.

 

[big stinkie]

AHA! You guys were right. I took an example of the problem to the paint shop, and they all said in unison, "Solvent Pop!" Turns out I was using both a reducer for the basecoat and an activator for the clear which were formulated for cool weather. (Duh) They said the basecoat exudes gas as well as the clear, so it's important to use proper reducers/activators for the basecoat AND clear. Otherwise the surface of the clear flashes and traps all the gas, leaving cute little bubbles just under the surface. Bought the right stuff for the current temp (Hot here in Kansas) and squirted the clear. Worked like a charm.

Sheesh...this painting stuff is complicated!

BTW, it is so hot here in Kansas that I saw a bird pick up a worm with a potholder! bada bing!

 

[big john 2]

I dont know to much about the 2082, but, I spray 2042 . after I put on a coat of clear I spray a colar card ( one of those thing u match colors with. it has a hole in the center ). I know when I am ready for a second coat when the clear on the color card is stringy to the touch. this help me with my solvent pop.

 

[rex]

Welcome aboard Big John.Sorry,gotta ask,how big are you?No,not that way

Sprayed any 2021?Holy sh!t is that stuff slow without cooking.

 

[Jim]

Funny you guys say"wait til it's stringy,HOK says wait til it's not,Guess differant companies have differant methods,here's part of HOK's tech sheet on clear:

Apply 1 medium coat with 50% pattern overlap., wait approximately 10-15 minutes (do "URETHANE FLASH TEST" below). Follow with 1-2 wet coats. Allow flash time between coats, usually 15-20 minutes. Gun distance while spraying should be approx. 6 inches. Air pressure at gun 50-55 PSI (may vary with equipment used).
URETHANE FLASH TEST - PAINT SHOULD BE STICKY AND NOT STRING WHEN TOUCHED AT THE WETTEST POINT BEFORE NEXT COAT IS APPLIED. (When using the flash test, always touch a new spot.) Monitor religiously for maximum merging of coats.

Dry time between wet coats is approximately 15-20 minutes depending upon shop conditions. High heat or high humidity conditions will accelerate cure time. Always check dry time using the flash test.

CAUTION: Too long a wait between coats can cause wrinkling or lifting. Also, too fast a recoat on hi-solid products (such as UC-35) can cause pin holes or solvent popping during cure.

Here's a link to HOK Products and tech sheets!!!

http://www.autobodysupply.net/houseofcolor/houseof.htm

 

[ezrider]

i have to agree with Jim,i wait until the clear stops stringing but is still sticky (make any sense) but waiting any longer than this will create problems as we all know. the only problem with this methiod is you have a very narrow time frame before things get very "COMPLICATED"

.