I have sold quite a few engravings on black marble including photos, wedding invitations etc. In an effort to improve the product, I've been looking for a coating to protect the finished engraving. I've tried Krylon clear gloss finish and it is close, but it does darken the engravings slightly.
Black marble is a relatively soft stone, and it scrathes fairly easily. Has anyone found a good protective finish that doesn't darken the engraving?