Since you're doing Ceramics, there's a Kilt, which fires your Ceramic Mold from clay into a hard item.
After you sand out the excessive clay, which is used to smooth materials to make your Ceramic item/s clean, smooth, then take a small sponge with minimum amount of water, and slowly, clean around the entire Ceramic item/s.
Let dry thoroughly. It gets fired in the Kilt again before painting your type of colors that's your idea way of beauty.
Then there is a Shellac, which is a mint green color. This is painted over your item/s thoroughly on your Ceramic item/s. This gives a Clear Coating for protection from Clay. It also gives your painting a Glossy Finish.
Then fired again in Kilt. When you get it back next time, it will have a sheen towards your goals.
There's some Ceramics that are not needing Shellac when you are making a Mold Painting.