Additional Info
What to know before you buy
A magnesia crucible is a common pick for melting or heating materials that would react with alumina or silica, such as basic oxides and some reactive metals. MgO has a very high melting point and stays stable under basic conditions, so it is used for melting metals and alloys and for firing oxide ceramics.
The range covers four sizes: the 10 mL MgO crucible, 30 mL, the 50 mL crucible and the 100 mL crucible. For the 30 mL size there is a 30 mm cover plate, which limits heat loss and keeps furnace debris out of the sample. A 26 mm diameter MgO block is also listed.
Pick the size based on sample volume, leaving headroom for foaming or expansion. For more on crucible materials, see the crucibles selection guide.
Frequently Asked Questions
When should I choose a magnesia crucible over alumina?
MgO suits basic melts and materials that attack alumina, such as some alkaline oxides and certain reactive metals. Alumina is often the first choice for general work. If your sample contains basic components or you see reaction with alumina, try a magnesium oxide crucible.
Which MgO crucible size should I order?
Fill a crucible no more than about two thirds to leave room for expansion. For small test melts, use the 10 mL crucible. For larger batches, choose the 50 mL or 100 mL size. The 30 mL size has a matching cover plate.
Do the crucibles come with lids?
A 30 mm MgO cover plate is listed for the 30 mL crucible. A cover reduces heat loss and keeps furnace debris out of the sample. For other sizes, check the product page or ask through the quote request page.
How should I heat MgO crucibles to avoid cracking?
Ceramic crucibles crack from thermal shock, so heat and cool them at a controlled rate and do not place a cold crucible into a hot furnace. Dry the crucible before first use, since MgO can pick up moisture from the air.
Can I order a custom size or a larger quantity?
Yes. MgO crucibles can be made in other sizes or shapes; send a drawing or dimensions through the quote request page. For several units of a listed size, use the bulk order request form.
