I had been cloistered away in my basement studio for weeks!! all to no avail. Recently I changed the type of kiln shelves I am using for firing, and can only surmise that this has affected the success in the finish products, or should I be more explicit the lack of success. It is so very frustrating to put in all that effort and expense (I don’t paint on cheap glass) and be dissatisfied. I recently converted to fibreboard shelves and have experienced etching on the underside of the painted glass. I made this conversion because I have two shelves in my kiln and to maximize the consistency in firing between the shelves I must rotate them during the hold time of the firing. Ceramic shelves get too hot and heavy to rotate with any ease, and whiting filled shelf trays can kick up dust onto the not totally fired glass during rotation. I experimented with new test firings using different shelf mediums like fibrepaper and whiting, changed temperatures and hold times all with inconsistent results. In some cases the glass suffered no ill effects then in later firings with precisely the same conditions I experienced a repeat of the problem. Thank goodness for electronic kiln controls because I can rule that out from the equation.
Never-the-less after over a week of moping around the house tonight I intend to go back down to “The Dungeon” (that’s what I call my studio when my projects are unsuccessful) and give it another try.
If anyone has experience with this type of etching, please drop me a line. When I resolve this issue I'll be sure to post and save anyone else the heartache.