20 years old greenware; will it fire properly?
20 years ago I made a navity, except for three pieces. I recently decided it was time to complete it. Pieces are in excellent condition. Will it fire without problems?
Well...yes and no. Let me answer that in two ways. The age of the greenware, especially if it is still in good condition, shouldn't affect the firing.
The main issue, though, is whether you remember at what cone (or temperature) the clay was designed to be fired? If you do, PERFECT! If not, I recommend starting by firing it to a very low temperature first.
If it is still porous (rapidly absorbs water) then try firing it higher. See the page of firing if you need tips. Good luck!