High Purity Mullite for Investment Casting
High purity mullite specifically graded for investment casting shells provides thermal stability and low thermal expansion. Falls under HTS 2508.60.00.00 as specialized mullite earth for industrial refractory use.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If prepared with chemical binders for shell-making
Mullite flour in prepared foundry additives classifies as chemical preparations.
If formed into shaped refractory pieces
Any shaped mullite products become ceramic refractories under 6902.
Not sure which classification is right?
Our AI classifier can analyze your specific product and recommend the correct HTS code with confidence.
Import Tips & Compliance
• Certify mullite phase purity (>98%) via X-ray diffraction reports for customs scrutiny
• Specify end-use as casting shell stucco to avoid precious metal melting crucible misclassification
Related Products under HTS 2508.60.00.00
Calcined Mullite Aggregate
Calcined mullite aggregate consists of crushed and heat-treated mullite grains used as a raw material in high-temperature refractories and castables. Classified under HTS 2508.60.00.00 as calcined mullite among other refractory earths.
Mullite Chamotte Grogs
Mullite chamotte grogs are fired, crushed mullite particles used as aggregate in refractory brick formulations. Classified under HTS 2508.60.00.00 alongside chamotte or dinas earths as processed refractory materials.
Bauxite-Derived Calcined Mullite
Bauxite-derived calcined mullite is produced by calcining bauxite to form the mullite phase, used in abrasive refractories. HTS 2508.60.00.00 covers this as calcined mullite distinct from raw bauxite ores.
Micronized Mullite Flour
Micronized mullite flour (D50 <5μm) serves as a fine filler in technical ceramics and casting slips. Remains under HTS 2508.60.00.00 as processed mullite powder, not chemical preparations.
Synthetic Mullite Powder
Synthetic mullite powder is a high-alumina ceramic material produced by sintering or fusing alumina and silica, used primarily in refractory applications. It falls under HTS 2508.60.00.00 as mullite, a specific aluminosilicate mineral classified among other clays and earths, whether or not calcined.
Fused Mullite Grain 200 Mesh
Fused mullite grain in 200 mesh size is electrically fused mullite for precision casting molds and advanced ceramics. It qualifies under HTS 2508.60.00.00 as processed mullite, not excluding fusion per chapter provisions.