Medium scale crucibles that are good for hobby level metalcasting are either difficult to acquire or are expensive. I'm experimenting with different ways of making them!
First Experiment (Slipcasting)
- I made a plaster mold out of USGS #1 Pottery Plaster
- slipcast recipe: scrap clay from old pottery making projects and a 10# block of High Fire clay from Michaels or Hobby Lobby. Add a tablespoon of Sodium Silicate for flavor.
- The first slipcast was allowed to develop its shell for about 3 to 4 hours. (the next one was allowed to sit overnight)
- the crucible was candled in the oven for 4 hours and then in the kiln for 2.
- it was fired for an unknown time, because the kiln turned off in the night, but judging from the firing pattern on the cone, it reached a respectable temperature before stopping
- Results of experiment
- The crucible stood up to the heat quite well, and provided a quite sufficient container for metalcasting.
- The crucible cracked slightly upon being set on the cold concrete, prior to pouring. It wasn't bad enough to prevent pouring, in the future, contemplate setting crucibles on a wood insulator. Wood will carbonize and the carbon would be a better insulator, buffering the crucible during the transfer.
- after the crucible was allowed to cool in the furnace, it was removed and tested for damage. The damage was severe, several hairline cracks all over the surface were observed.
- The crucible was pulled into shards by hand.