Information about lettering used in the Pet grave markers and other markers and molds REVERSE LETTERING: To temporarily fasten reverse lettering and or/ numbers so that they can be removed and reused to cast different information in the markers---we use these products, which are actually CAULKING MATERIAL. General Purpose 100% Silicone CLEAR (use with caulking gun) All weather Protection 10.1 oz tube You can use other clear caulking silicone products which are sold in a small tube. After you fasten the letters & numbers in the mold, First let them set up for an hour or so. After it sets up a little, you can trim excess material from around lettering. Then apply a release agent very carefully so you don't move the letters!! Your ready to pour!!!!! BE SURE TO CLEAN THE MOLDS AND THE LETTERING WELL AFTER EACH USE WITH SOAP AND WATER......DISHWASHING LIQUID WORKS WELL.. FOR STUBBORN RESIDUE TRY A LITTLE WD-40 ...