The residue is at full
The residue is at full fusing. If I have two sheets of glass that I am fusing together and the bottom sheet is opaque, it seems to have more of a chance to have a kiln wash residue that is very difficult to get off, It has also happened with transparent glass but not as much. If I am full fusing into a mold with frit sometimes the finished product has small spots where the kiln wash sticks. I had understood that primo primer was much better than other kiln washes but I am having these issues and am curious what other people are doing to prevent this. When I have a clean non-primed shelf, I give it 4-5 coats of kiln wash as recommended. After the inital firing if the shelf is still in good shape I will renew the kiln wash with 1-2 coats as recommended by manufacturer. I do remove the kiln wash residue when it shows wear and start fresh.