I know, it might not be a food
safe coating, just appears to be, I never noticed it degrade except when exposed to UV sun. And the company has no point to testing for that as that use is outside what designed for.
Over the last 10 years, I must have used a few hundred 30 oz tubes. Ground it, sanded it, breathed a lot of PL dust, got it all over my skin and never felt a thing.
You can mix PL with sawdust or anything dust like really and it will cure full thickness to a nice sandable (with coarse) filler material. Good for plugging holes and rebuilding repairing wood. I also rebuilt rocker panels
on a Ford with aluminum
sheet, rivits and PL mixed with sawdust to recontour the shape. It is a great seam sealer expanding adhesive
to glue and gap seal between metal sheets
I have even repaired cracked plastic radiator end covers with PL and sawdust and it holds up, for that needs around 1/4 inch thick layer.
It bubbles and swells when exposed to moisture during the cure phase.
You can use a plastic cereal bag to press down the bubbles during the cure as it wont stick to PE plastics.
So far going on 6 months and no leaks
This is why I KNOW it holds up to heat.