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mikes409
06-07-2007, 08:13 PM
I would like some info on fixing sags and runs in the clear ?I also need info on a fix for sanding through the clear into the base coat what should i do ? I have a door that is the worse with sags and runs can i sand down to the base and then repaint with base then reclear?
Thanks from mikes409:confused:

Len
06-07-2007, 08:33 PM
Different paint products react differently when re-coated. There are some that can be re-coated when you sand through the clear and some that react to the new coating.

I would repair the runs first THEN decide on how and where to apply more paint. The page on Run Repair is located HERE (http://www.autobodystore.com/run_repair.htm).

Once the runs are leveled you can decide which areas need more paint.

To re-coat the places that you've sanded through the clear you'll need to apply color AND clear to make it right. Clear alone won't do it. Depending on the type of paint you may need to apply a seal over the hole so that the new base coat doesn't react with the repair area. I would probably recommend either laying a coat of 2K primer or more clear over the spot(s) then sand before you apply more base and clear. If you're only repairing a few spots then the base can be sprayed over the repair and blended onto the surrounding panel then the entire panel can be cleared. If the repairs are extensive it usually pays to apply an entirely new base and clear coat after the repairs are sealed.

mikes409
06-08-2007, 08:04 AM
Thanks for the info the paint and clear is the best you can buy ,ppg.
I will try to fix my boo boos ,one more thing when i sanded down a run it still seems like i can see a shado in the clear of the run when you look at it a certain way?
Thanks from mikes409

88GT
06-08-2007, 08:56 AM
Thanks for the info the paint and clear is the best you can buy ,ppg.
I will try to fix my boo boos ,one more thing when i sanded down a run it still seems like i can see a shado in the clear of the run when you look at it a certain way?
Thanks from mikes409
If you dont block the run completely flat, it may appear to be gone until you polish it. Just block a little more

cjohnson
06-08-2007, 09:48 AM
You didn't mention which line of PPG base coat you're using. It's most likely DBC which does like to lift if you try to recoat a sand through. Len describes how to avoid the lifting problem by "sealing" the sand through with clear or primer. The only thing I will add is from my experience clear is good but it can cause a problem if it is sprayed to wet. I find epoxy primer is the safest bet when using PPG DBC.

JCCLARK
06-08-2007, 09:50 AM
Most times a run will shadow line because it's softer than the surrounding
paint, it's softer because it was thicker-it takes longer to harden.
That's why the longer you wait to level and buff the better.
I usually use a hard piece of wood sanded flat and wrap it with 1000 grit
paper with no cushion. I'll sand just to where it's almost gone then let it sit
a day. Out in the sun is the best. The longer the better.
Then sand it more to level then with 2000 grit and buff.
If it's softer than the surrounding paint it'll always buff differently.
You have to get it to harden completely for best results, and if you thin
it first, it'll harden faster.:cool:

Len
06-08-2007, 12:27 PM
Most times a run will shadow line because it's softer than the surrounding
paint, it's softer because it was thicker-it takes longer to harden.
That's why the longer you wait to level and buff the better.
I usually use a hard piece of wood sanded flat and wrap it with 1000 grit
paper with no cushion. I'll sand just to where it's almost gone then let it sit
a day. Out in the sun is the best. The longer the better.
Then sand it more to level then with 2000 grit and buff.
If it's softer than the surrounding paint it'll always buff differently.
You have to get it to harden completely for best results, and if you thin
it first, it'll harden faster.:cool:

I find that removing the run while the paint is soft will actually help the leveling process. I usually shave and do the initial sanding within the first 48 hours then allow the newly exposed paint to harden/shrink then re-sand using a Run Blocker to help level the surface even more. The shrinking helps to make the surface more level than if you waited for full cure because you have less chance of sanding through around the run when the shrinkage helps level the surface. If the run repair is done after the paint is fully cured more care needs to be taken and you usually find that it pays to stop sanding prior to getting the surface totally flat.

88GT
06-08-2007, 12:34 PM
I read on a custom paint forum I go to occasionally, that applying polly putty over the run and blocking it that way would help prevent sanding through. Never tried it, but seems like a pretty good idea on a bad run

Len
06-08-2007, 12:39 PM
I read on a custom paint forum I go to occasionally, that applying polly putty over the run and blocking it that way would help prevent sanding through. Never tried it, but seems like a pretty good idea on a bad run

That's sounds interesting I'll give it a try and let you know what happens.

mikes409
06-08-2007, 04:15 PM
Thanks for all the info . has anyone heard of mealting in a area repair ?
Thanks from mikes409:confused:

Len
06-08-2007, 05:08 PM
Thanks for all the info . has anyone heard of mealting in a area repair ?
Thanks from mikes409:confused:

That's a new one on me.

88GT
06-09-2007, 08:20 AM
That's a new one on me.
I think he means melting in a blend on a repair area.

Hannibal
06-09-2007, 10:17 PM
When nibbing a sag, if it is deep, you may get solvent pop right at the area of a sag. I tried to nib the whole sag in one sitting, and it happened to me. The clear underneath is soft and may still have trapped solvent.

so try to nib it down slowly, even if you give it a few hours of sun between nibbing/sanding you may avoid this.

Len
06-09-2007, 10:58 PM
I think you'll find that the bubbles are already formed in the clear and it won't matter how fast or slow you shave down the paint the bubbles will still be there. The solvent pop bubbles will be formed when using some combinations of hardener and reducer and NOT be formed with others.