Geber
Member
Has anyone observed liquid sweating out of their melt dishes? I have been having this problem and it makes pouring the metal impossible.
Not too long ago I bought some melt dishes, heated one to drive away moisture, glazed it, and melted some fine silver in it with no problems.
Then I used it about a week later and a liquid started coming out of the ceramic when the silver was nearing its melting point. This liquid took a glass-like appearance when cooled, and exploded with a pop when it was quenched. I reasoned it was excess borax, that the dishes somehow came glazed with borax, and that I should not glaze the next one. I then used an unglazed one, and the metal did not stick inside, but the same liquid appeared. It also seems to be taking too long to melt the silver with MAP gas and that I have to use way too much gas.
Finally, I used my graphite crucible in my little furnace. The crucible had also been sitting around in my shop, which can get damp, and I did not condition it. When it got to temperature, I looked in the crucible and saw an orange liquid. It was slightly steaming, convecting vigorously, and spitting out the occasional tiny orange spark. Thinking it was the silver, I poured it into my mold, and poured a bar which was dark-red and blackish in color. I emptied the mold and the "bar" fragmented into pieces. The silver was adhering to the side of the crucible, and was never totally melted. I did not put anything in this crucible besides silver and a little pinch of borax.
Can anyone tell me what I'm doing wrong? Do I have to drive the moisture out of melt dishes and crucibles every time I use them, and is this liquid a saturated water-borax mixture? Thanks!
Not too long ago I bought some melt dishes, heated one to drive away moisture, glazed it, and melted some fine silver in it with no problems.
Then I used it about a week later and a liquid started coming out of the ceramic when the silver was nearing its melting point. This liquid took a glass-like appearance when cooled, and exploded with a pop when it was quenched. I reasoned it was excess borax, that the dishes somehow came glazed with borax, and that I should not glaze the next one. I then used an unglazed one, and the metal did not stick inside, but the same liquid appeared. It also seems to be taking too long to melt the silver with MAP gas and that I have to use way too much gas.
Finally, I used my graphite crucible in my little furnace. The crucible had also been sitting around in my shop, which can get damp, and I did not condition it. When it got to temperature, I looked in the crucible and saw an orange liquid. It was slightly steaming, convecting vigorously, and spitting out the occasional tiny orange spark. Thinking it was the silver, I poured it into my mold, and poured a bar which was dark-red and blackish in color. I emptied the mold and the "bar" fragmented into pieces. The silver was adhering to the side of the crucible, and was never totally melted. I did not put anything in this crucible besides silver and a little pinch of borax.
Can anyone tell me what I'm doing wrong? Do I have to drive the moisture out of melt dishes and crucibles every time I use them, and is this liquid a saturated water-borax mixture? Thanks!
