Crucible - #A0
A crucible is a ceramic container use to hold metal for melting in a furnace.
What It Does:
A crucible is needed to withstand the extreme temperatures encountered in melting metals. The crucible material must have a much higher melting point than that of the metal being melted and it must have good strength even when white hot.
It is possible to use a home made steel crucible to melt metals such as zinc and aluminum, because these metals melt at a temperature well below that of steel. However scaling (flaking) of a steel crucible interior surface is a problem. This scale can contaminate the melt and thin the crucible walls rather quickly. Steel crucibles will work if you are just getting started and don't mind dealing with the scaling.
Common refractory materials used in crucible construction are clay-graphite, and carbon bonded silicon-carbide. These materials can withstand the highest temperatures in typical foundry work. Silicon carbide has the added advantage of being a very durable material.
The "A" shaped crucibles are useful for metals up to 2000 °F (1093°C). They will handle zinc, aluminum, brass / bronze, silver and gold alloys. Made in China.
"A" Shape: Our "A" shape crucibles are typically used by hobbyists and casual casters. This shape is easier to make than the bilge shape and therefore is lower cost. Also note that "A" shape sizes and capacities don't correspond to bilge shape sizes and capacities. For example a #A0 will hold about 0.9 pounds of aluminum or 2.2 pounds of brass. This crucible is about the size of a small teacup.
These "A" shape crucibles are formed from what appears to be clay, fire clay grog and a smattering of silicon carbide particles.
How To Use It:
All crucibles should be handled with properly fitting tongs (lifting tool). Improper tongs can cause damage or complete failure of a crucible at the worst possible time.
A disk of cardboard can be placed between the crucible and the furnace base prior to heating. This will burn off, leaving a layer of carbon in between and prevent the crucible from sticking to the furnace bottom. A coating of Plumbago (Carbon Black) does the same thing.
It is best to use a different crucible for each type of metal to avoid contamination. Also be sure to completely empty the crucible after use. Metal left to solidify in a crucible can expand on re-heating and destroy it.
Please temper new crucibles or those that have been in storage. Heat the empty crucible for 2 hours at 220 F (104 C). (Use adequate ventilation. New crucibles will smoke as the glaze sets.) Then fire the empty crucible to a red heat. Allow the crucible to cool to room temperature in the furnace before use. This procedure should be followed for ALL new crucibles and for any crucible that may have been exposed to damp conditions in storage.
Store all crucibles in a dry area. Moisture can cause a crucible to crack on heating. If it has been in storage for a while it is best to repeat the tempering.
The material should be placed into the crucible VERY loosely. NEVER "pack" a crucible, as the material will expand on heating and can crack the ceramic. Once this material has melted into a "heel", carefully load more material into the puddle for melting. (WARNING: If ANY moisture is present on the new material a steam EXPLOSION will occur). Once again, don't tightly pack in the metal. Keep feeding the material into the melt until the required quantity has been melted.
WARNING!!!: Crucibles are dangerous. Melting metal in a crucible is dangerous. Pouring metal into molds is dangerous. A crucible may fail without warning. Crucibles can contain hidden defects in materials and manufacturing which can lead to failure, property damage, personal injury, injury to bystanders and loss of life. By purchasing a crucible from Budget Casting Supply LLC the purchaser agrees to assume all risks and agrees to indemnify Budget Casting Supply LLC from all losses arising from their use.