I've been looking into this Sharpie+mug+350 degrees craft and it looks as though many people have been experiencing fading or the colors coming off altogether. Therefore, I would like to share this blogger's page. She explains to the tee how she cooked her mug at 425 for 30 minutes and then left the mug to cool in the oven. The results: a permanent cup at last! Check this out!
How to Fix a Dried Out Sharpie..most of the time, according to this website, it is the nib that is dried out, not the ink! Soak in alcohol...worth a try! I have many a marker which has dried out, but not been thrown out. Perhaps this will fix them.
9′x6′ drop cloth & broad tip Sharpie Markers Cut your drop cloth to fit your tables need. Hem your cut edge WITH TAPE! Iron out the creases in order to have a smooth writing surface. Before laying out the drop cloth on your table add butcher paper or newspaper to help avoid getting ink on your table CURTAINS TOO?