The Quick/Small/Stupid Question Thread

M

mitch_04

Learnin'
Another forum I frequent has a thread dedicated to small/quick/stupid questions and it's awesome for questions that people have but don't want to dedicate a thread to. A shame free zone where questions can be asked and answered without being made to feel like an idiot. I figured I'd start one here since I always find little questions throughout my work. Some are pure curiosity and not technical, perfect for a thread like this.

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I'll start it off.

If I epoxy over 40 vs 80, what is going to happen? Will 40 not have enough adhesion, or is it just that the epoxy won't fill the sanding scratches?
 
Oh, well, I thought someone else would chime in. Generally we like to see as fine a grit as you can manage with your bodywork, because of the fact that primers contain solvents that evaporate out and cause the coating to shrink. Good products do this less, and if you are really taking your time between primer sessions the situation gets even better. But the coarser the grit that is primed over, the more obvious any shrinkage will become. Finishing in smooth grits is just an insurance policy against that final bit of shrinkage that happens when the vehicle gets done and sets out on the July sun for a few weeks. If everything was done right, it will still look fine. If some solvent happens to escape that was in an area where there were deep scratches, chances are they will show bad. But if the scratches were fine, they may not show at all, or might come out with a bit of light sanding and buffing.

It's just good accepted practice to finish filler work as fine as you reasonably can. Around here that means anywhere from 150 to 320, depending on the job.
 
Sounds good. I've found that 40 grit removes old paint and filler much faster and seems to last longer than 80 grit. Taking the 40 grit scratches on metal to 80 grit really seems to destroy paper. I have long, long amounts of time between epoxy and other layers, so I should be able to control the shrinkage rather well. Thanks.

Everyone, jump in and ask a simple or quick question, let's get this thread rolling!
 
The trick with 40 is to try and stop at the last layer before the metal, and finish with 80. Also there are different sandpapers for paint/filler and metal.
 
Alright, another quick question. Just applied some Universal Clear and I'm wondering how long until it can get wet? I need to wash and buff the rest of the pickup.
 
It's never the same, you have to go by experience, taking into account how warm, how humid, and how long it has been. Under normal conditions, about 12 hours is enough, though the paint will still be soft enough to be able to fingerprint if you push hard, it will be cured enough to handle a gentle wash.
 
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