I am on a residency in Japan and a lovely artist here gave me a catalogue for ordering supplies. I ordered what I assumed to be underglaze, but since it came in powdered form, I asked the artist whether I can buy 'frit' to add to it (as maybe it is really a stain ?) but she says she usually mixes the powder with 'steeped green tea'. I mixed the underglaze powder and green tea with mortar and pestle and applied it on my greenware using a spatter brush (really fine spatters, light layers). It dried quickly, but like my previous experience with stains, it comes off or smudges with even the most gentle touch.
I read somewhere that I can perhaps seal it off with an artist fixative to prevent smudging before a firing, but am afraid that it won't burn out completely in the bisque firing. Any body have experience with 'fixing' stains / powdered underglazes with an artist fixative ? I have a feeling it might come off even after the first firing anyway but since it's already on my wares, I want to safely transport (without smudging) them to the kiln and give it a try.