Yellow decals

Taping it to the inside of a window will work because the wavelength needed is longer wave UV- some does get through the glass.  Quicker to tape it outside in direct sun, but you have to check it every hour or so to keep from bleaching out the ink colors you want to stay.  As soon as yellow is gone, take it in.

Also, I find direct sunlight does well to harden those UV glues.  They do not completely harden with the few seconds of UV from the gadget in the kit- they are pretty hard but do completely harden with about 20 minutes of direct sunlight.

Hi Don! I have an F6F-5 Hellcat on the bench to work on after my SBD Dauntless. All the white decals have yellowed on the sheet. I took your advice and taped the decals to the window on Saturday. I checked them every day. When I checked them this afternoon the yellow was gone and the whites are white again. Doesn't look like any damage to the other colors.

Thanks for the advice!

Jim 

Stay Safe.

It works for sure.

One caution; don't use a window that gets condensation on the inside!

Thanks for that tip. It's a good thing that I checked them often. Planning on doing it with a couple more old decal sheets.

Jim 

Stay Safe.