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skip99
11-01-2014, 02:12 PM
Hood turned out real nice ..for a day....it was painted about two months ago, sat til two weeks ago. wetsanded buffed and was perfectly smooth. Then saw a few scratches, So wetsanded again, 2000,2500. Again, looked great....today , i can see scratches again. The hood is th only place its this bad. Actually it isnt bad. You can tell from the pics, you have to be inches from it to see, and light at the right angle.
So, what ya think?
Is it smooth after buffing because of the heat? And then cools and shrinks?

Possible that even after two month its still soft?

http://i488.photobucket.com/albums/rr241/skip99202/imagejpg4_zpsa8af13d7.jpg (http://s488.photobucket.com/user/skip99202/media/imagejpg4_zpsa8af13d7.jpg.html)

http://i488.photobucket.com/albums/rr241/skip99202/imagejpg3_zpsca42a3e6.jpg (http://s488.photobucket.com/user/skip99202/media/imagejpg3_zpsca42a3e6.jpg.html)

http://i488.photobucket.com/albums/rr241/skip99202/imagejpg2_zps1fdab628.jpg (http://s488.photobucket.com/user/skip99202/media/imagejpg2_zps1fdab628.jpg.html)

Len
11-01-2014, 04:41 PM
Is it a metal or fiberglass hood? If it's glass then it could be the texture that's coming back to haunt you.

If it's metal what primers were used, starting at the metal, and how was each primer sanded?

skip99
11-01-2014, 06:43 PM
Metal....started bare metal, sprayed epoxy.did some Bondo in places, blocked and da sanded the bondo to 120,maybe 180....then featherfill g2. Blocked quick with 80 , just to make sure it was straight, then blocked and da to 220.
2k primer , block and wet sand to 400. Sat a couple weeks, sprayed black base ppg dbc. Sat overnight, sprayed 3 coats clear.

Omni epoxy, omni primer, dbc black, omni clear.

I could put it out on sunny day, but temp wont be above 55

Len
11-01-2014, 10:27 PM
Metal....started bare metal, sprayed epoxy.did some Bondo in places, blocked and da sanded the bondo to 120,maybe 180....then featherfill g2. Blocked quick with 80 , just to make sure it was straight, then blocked and da to 220.
2k primer , block and wet sand to 400. Sat a couple weeks, sprayed black base ppg dbc. Sat overnight, sprayed 3 coats clear.

Omni epoxy, omni primer, dbc black, omni clear.

I could put it out on sunny day, but temp wont be above 55

It could be the low cost primer that is a little unstable and black shows everything. Sometimes an unstable primer can never become stable but I'd put it in the sun and allow it to get hot for a day or two then level it again to see if it stabilizes. Even if the air temperature is cool the sun will heat that black paint and maybe it can stop the problem.

skip99
11-02-2014, 07:56 AM
But whats the problem? Its cool metal now, if i sand it flat, and then buff, you think the heat fom buffing is swelling the primer , hich is leveled as i buff, and then when itcools it shrinks back into scratches that the primer had filled?
So maybe change primer, on this next car......any suggestion in the ppg line? What about the omni plus line?

Len
11-02-2014, 09:25 AM
But whats the problem? Its cool metal now, if i sand it flat, and then buff, you think the heat fom buffing is swelling the primer , hich is leveled as i buff, and then when itcools it shrinks back into scratches that the primer had filled?
So maybe change primer, on this next car......any suggestion in the ppg line? What about the omni plus line?

No, it's probably that the primer doesn't become as stable and causes some movement as the temperature changes or the coatings age. If it was a lighter color you probably wouldn't even notice it but black shows everything especially on the top horizontal surfaces that get direct sunlight and are right up in your face. This is one of the reasons I use expensive materials on jobs that need to be perfect.

junk
11-02-2014, 10:16 AM
On color I've liked the omni plus line over the omni line. I've never used their primers though. I would probably recommend the omni plus or PPG shop line for a value based PPG line. As I understand it the PPG shop line is basically OMNI plus with a little different mix of products.

What level of scratch is feather fill rated to cover?

skip99
11-02-2014, 10:38 AM
On color I've liked the omni plus line over the omni line. I've never used their primers though. I would probably recommend the omni plus or PPG shop line for a value based PPG line. As I understand it the PPG shop line is basically OMNI plus with a little different mix of products.

What level of scratch is feather fill rated to cover?

It says 180 to 220

skip99
11-02-2014, 10:41 AM
Could it be 80 grit scratches in the bondo, that i maybe didnt get all out and filled with the featherfill? I would have thought ff wouldnt shrink or move?

I guess im trying to figure out where the problem is.
Bondo too rough before ff? If thats the case then the primer is not an issue.

If the ff is stable, then it has to be the omni primer?

Surface temp is 140 in the sun right now, should be two days of sun here.

Len
11-02-2014, 04:08 PM
Could it be 80 grit scratches in the bondo, that i maybe didnt get all out and filled with the featherfill? I would have thought ff wouldnt shrink or move?

I guess im trying to figure out where the problem is.
Bondo too rough before ff? If thats the case then the primer is not an issue.

If the ff is stable, then it has to be the omni primer?

Surface temp is 140 in the sun right now, should be two days of sun here.

Yes, it could be the 80 scratches because deep scratches that are filled over with a different material can show depending on the materials used. I've never had a problem with Slick Sand over filler but it depends on ALL of the materials (filler, primers, paint) used. The more solvent the more likely you are to have a problem like this and if you used an inexpensive filler it could be less stable. It takes a long time for solvent to go away if you trap it under your top coat and if that's the case you could see this reaction for months. Did you use solvent in the Slick Sand and how long was it before the Slick Sand was sanded and recoated?

skip99
11-02-2014, 06:04 PM
Used 3m platinum bondo, the featherfill sat a couple weeks before prime, primer sat a few weeks , even in the sun a few days..might have thinned the ff, with a little acetone, no more than 10%

Len
11-02-2014, 06:46 PM
Used 3m platinum bondo, the featherfill sat a couple weeks before prime, primer sat a few weeks , even in the sun a few days..might have thinned the ff, with a little acetone, no more than 10%

I don't use any of those materials but I'd probably wait and let the sun work on stabilizing the surface for at least a couple weeks longer before you level it again and see what happens. If that doesn't work I think the only option then will be to sand back down to the filler to level the 80 scratches then reprime and paint.