Runs in epoxy sealer & base-how to fix?

MDPotter

Promoted Users
I was fully ready and anxious to paint the cab this weekend, but I realized my mistake after spraying which was that I over-reduced my epoxy sealer. Instead of reducing it 50%, I reduced it 100% (1 part epoxy, 1 part activator, 2 parts reducer). So I had a few runs in the sealer due to the low viscosity. I waited a couple hours and wet sanded very carefully and got them leveled down, but then I had issues with the base in those spots as well as a few runs (my first time spraying SPI base-it seems to go on heavier/wetter than Chromabase or Wanda) so I decided it was best to stop and resand everything and try again.

My question is - what is the best way to fix these runs? I want to use a coarse enough grit to level them but not dig a hole at the same time. I was thinking 320? Then I was thinking I would spray 2K or unreduced epoxy as the final surfacer in prep for sealer/base/clear.


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Dean

Promoted Users
If i read tech sheet right.....if reapplying epoxy its supose to be sanded in 180, id expect burn throughs anyways by time these are sanded out.
Reduce epoxy 25%. Reshoot areas needed. Do your final sand again in the areas, If your happy with the body work then just paint it, or seal and paint if you want. Doesnt need 2k if body is good to paint
 

Chris_Hamilton

Trying to be the best me, I can be
When using epoxy as a sealer there is no need to sand it with 180. That only applies when you are re-coating un-reduced epoxy with more unreducedepoxy after the 7 day window.
Personally I would go 600 wet with a suitable block and sand it all. Doing as Elwood suggested and using 400 wet, to knock the majority of the runs down would be a good idea. Sneak up on it by sanding lightly. Change your paper often. Check your progress often. Keep all your sanding scratches going in one direction. Pay attention while your sanding to what is happening. Doing so will help you from breaking through too much. When done, wipe everything down again and re-seal.
 
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MDPotter

Promoted Users
Thanks for the advice guys. I'll use fresh paper and be deliberate in targeting/knocking down the runs. Looking forward to sanding the cab again!
 

crashtech

Combo Man
I would be wondering if those runs will smooth out adequately with fine grits. Sometimes starting with a little 320 on the worst spots can help make it straighter, faster. It might need some unreduced epoxy sprayed on the repair areas with some sanding to fix them, imo.
 

MDPotter

Promoted Users
I would be wondering if those runs will smooth out adequately with fine grits. Sometimes starting with a little 320 on the worst spots can help make it straighter, faster. It might need some unreduced epoxy sprayed on the repair areas with some sanding to fix them, imo.
I'm prepared to apply more epoxy if I have to; no big deal.
 

crashtech

Combo Man
You'll want to look and feel those areas carefully, it's a bummer to have the remnants of runs showing in the final finish. Sometimes wetting the areas with solvent based wax & grease remover and catching the reflections can help you see if the surface is smooth enough. Some of these things can be too subtle to feel but will still show later.
 

Chris_Hamilton

Trying to be the best me, I can be
I would be wondering if those runs will smooth out adequately with fine grits. Sometimes starting with a little 320 on the worst spots can help make it straighter, faster. It might need some unreduced epoxy sprayed on the repair areas with some sanding to fix them, imo.

I guess you never get runs. :) I wouldn't have said what I said if it wouldn't.:rolleyes: 400 grit wet (equivalent of 320 dry) is more than adequate. 320 dry in a novice's hands is too coarse. 400 wet to knock the tops off, 600 wet over all the epoxy. For a novice this is far safer than doing it dry.
 

Dean

Promoted Users
When using epoxy as a sealer there is no need to sand it with 180. That only applies when you are re-coating un-reduced epoxy with more unreducedepoxy after the 7 day window.
Personally I would go 600 wet with a suitable block and sand it all. Doing as Elwood suggested and using 400 wet, to knock the majority of the runs down would be a good idea. Sneak up on it by sanding lightly. Change your paper often. Check your progress often. Keep all your sanding scratches going in one direction. Pay attention while your sanding to what is happening. Doing so will help you from breaking through too much. When done, wipe everything down again and re-seal.
My comment wasnt about just sealing it. I try not to seal anything if i can. 180 was when he burns through and needs to prime again.
Personaly they look to heavy of runs to just go lightly to save it, id ecpect to see it show after. Thier prob wet inside still also and would be messy sanding with it clogging paper and leaving gouges. Prob faster to just cut it and reprime too.
 
Having lots of experience dealing with runs, I have found using a hard block, like a piece of oak, to sand with works wonders.
You can use a course grit like 320 or 400 ;) and just knock the tops of the runs of. The hard block will not flex and touch the areas around the runs.
Take your time and sand the runs down to just above the surrounding surfaces, then you will want to switch to a finer grit and continue sanding the runs until they are level with the surrounding areas. At that point you can wet sand the area and should not be able to see or feel where the runs were.
 

MDPotter

Promoted Users
Appreciate all the feedback everyone. I don't know if I have any 400, but will get some if not. I'm not concerned about breaking through-I'm already expecting to and am prepared to apply more epoxy. I would rather level the runs and break through in the process than go too fine on grit and have remnants of runs in the final surface.
 
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