If you are using Thinfire do
If you are using Thinfire do not put dichoric or iridised in contact with it. It creates craters in the glass through some kind of reaction. I don’t know if that applies to the other thin papers. It does not seem to have the same effect with ceramic fibre papers, although they give rougher textures.
The safest thing to do is to kiln wash the shelf and fire on that rather than paper when you have dichoric or iridised face down to the shelf.