I want do a little spot touchup is nail polish fuel proof ?

I use clear epoxy thinned with a little alcohol. Works great.

no finger nail polish is not fuel proof..use the epoxy cut 50/50 with alcohol....you shouldn't need a touch up as the epoxy penedrates the wood....unless of course you have wood that has become uncovered.....
Good Flyin

Where do you want to do the touchups?

If you want to touch up the graphics to make them stick better then yes, clear fingernail polish will work very well. It's what I use and I am very happy with the results. And you only need to coat the edges.

But DO NOT use a cheap $1 bottle from Dollar Store or anything like that. It must be a well-known brand, and has to be clear, I use L'Oreal Top Coat#110

If you want to touch up the firewall or tank area, then NO, fingernail polish won't do. Thin epoxy with a few drops of denatured alcohol and brush it on. If you do not have denatured alcohol, which is best to use, then regular isopropyl alcohol will work (get the highest percentage you can get for best results). If you can't get alcohol then you can heat the epoxy to thin it, but brush it on quickly as it sets very fast.

I notice when i use a drop of alochol to get some (still wet) expoxy off my fingers it seems to dissolve and remove it comopletey sort of eating it up...

Question: Why does this not happen when you use the epoxy, alcohol combo to bond wood.

For fuelproofing my firewall.. I have been painting epoxy on full strength (a somewhat light coat) then hit for 5 seconds with my covering gun and it flows like a thinned syrup into all the nooks and crannies while still keeping it's full strenght mix. I haven't had any issues yet to date.

I can't explain why it works but I love your suggestion for applying the epoxy full strength and then hitting it with a heat gun. Just be careful that it doesn't flow into the blindnuts.

Because alcohol will thin uncured epoxy, so when you remove it from your fingers, you are removing 1 part epoxy with 50 or 60 parts alcohol (The amount of epoxy on your finger compared to the amount of alcohol on the paper towel)

If you let that towel sit for a while, the alcohol would evaporate and the residual epoxy would cure, but there is SO little epoxy spread over such a wide area, that at most, you might notice a miniscule amount of stiffening of the towel.

When you mix epoxy with alcohol, the alcohol thins the epoxy just as it does when you remove it from your fingers, but now we are dealing with a LOT more epoxy and about the same amount of alcohol. This time, the ratio is more like 5 parts epoxy to 3 parts alcohol (5 to 3 instead of 1 to 60).

That said, it is best to use Denatured alcohol or Isopropyl (Rubbing) alcohol with a low water content. The water won't hurt the epoxy's fuel-proofing ability.

And in any case, Acetone is better to use than alcohol.

I wanted to use nail polish because the color matches the plane