Clean an alumina crucible according to what remains inside it. Inspect it for damage first; a cracked crucible or a deposit that has reacted with the ceramic may need replacement. There is no single cleaning temperature or acid bath for every sample.
Inspect before cleaning
Let the crucible cool under your process instructions. Identify the previous charge and any residue before handling it or adding water. Check the wall, base and rim for cracks or chips. Almath advises inspecting incoming crucibles and never putting damaged ones into service. Keep a damaged vessel out of the next heating run.
For loose residue that is compatible with water and detergent, Iowa State’s TGA laboratory procedure starts with mild soap, removal of loose solids and a water rinse. Its later steps belong to a controlled laboratory method. They are not a cleaning cycle validated for GY products.
Choose the method by residue
| Residue | Choose the next step |
|---|---|
| Loose | Identify the solids and check compatibility with water or detergent. Use the approved wash method; inspect again after removal. |
| Organic | Check fillers and reaction products. NETZSCH discusses furnace burn-off, but warns that oxide fillers can react with alumina. |
| Metal | Identify the metal or alloy. Use a laboratory-approved method for that residue; do not choose an acid from appearance alone. |
| Fused | Check for reaction with the ceramic. NETZSCH notes that some oxide deposits cannot be removed; replace the crucible when the deposit cannot be cleared. |
NETZSCH’s original instructions separate alumina from platinum. HF attacks alumina; a method listed for a platinum pan must not be copied to an alumina one. Use the laboratory’s approved chemical procedure and facilities for any chemical cleaning.
Furnace cleaning also needs the residue, crucible grade and furnace limits checked together. We do not specify a universal burn-off temperature or dwell time. For handling after a wash and during heating or cooling, see the sourced recommendations in our alumina thermal-shock guide.
Check the crucible against the next process
A clean-looking surface does not establish that a crucible meets your contamination limit. Record its previous contents, cleaning method and inspection result. If your analytical method requires a blank or baseline check, complete that check before the next sample. Replace the vessel if its history or condition cannot meet the method’s requirements.
For TGA and DSC, compare the replacement with the instrument’s specified pan. METTLER TOLEDO lists material, volume, mass and base flatness among the selection factors, along with sample, atmosphere and instrument compatibility. Matching capacity alone is insufficient. Our catalog crucibles are not a verified replacement range for a named instrument.
What to send for a replacement crucible
Our crucible, boat and lid tables show typical dimensions, with exact dimensions confirmed in the quotation. Send the shape and drawing as well as the capacity; two crucibles with the same volume can have different rims and bases.
- Shape, top diameter, base diameter and height; required internal dimensions and tolerances.
- Alumina grade, sample or charge, atmosphere and operating temperature.
- Lid dimensions and fit, quantity and required delivery date.
- For an instrument pan: instrument model, original part reference and the dimensions or drawing it must match.
Include a photograph of the used crucible and describe the residue or damage. We can quote the replacement part from those details; a cleaning method and a reuse limit need validation for your process. Send the crucible specification.
Questions buyers ask
- Can an alumina crucible be reused?
- An intact crucible may be reusable if the residue can be removed and it meets your next process’s contamination limits. Inspect it first and follow a cleaning method approved for the sample and crucible. GY Alumina does not publish a guaranteed reuse count.
- Can hydrofluoric acid clean an alumina crucible?
- NETZSCH warns that HF attacks alumina as well as oxide deposits. Do not transfer a platinum-crucible cleaning method to an alumina crucible.
- Is a small alumina crucible automatically suitable for TGA?
- No. Equal volume does not establish compatibility. Check the instrument model, pan geometry, mass, base flatness, lid and sample-changer requirements. GY’s catalog dimensions do not establish instrument compatibility.
Sources
- NETZSCH: Recommendations for Cleaning Al₂O₃ and Pt Crucibles
- Iowa State University: TGA alumina crucible cleaning procedure
- Almath Crucibles: alumina crucible instructions, handling with care
- METTLER TOLEDO: alumina crucibles for thermal analysis and selection factors
- Our own figures: the factory’s standard-size list, 2026 orders and test report, as recorded in our product catalog.