Laboratory crucibles: how can a crucible be selected for high-temperature treatments?

Indispensable for calcination, incineration and alkaline fusions, crucibles ensure the mechanical and chemical integrity of samples at high temperature. The choice of material—porcelain, alumina, platinum, nickel, quartz, PTFE, glassy carbon—governs purity, safety and service life. From gravimetry (LOI/ROI) to sample preparation for XRF/XRD, in a muffle furnace or over a burner, our crucibles meet the needs of laboratories in the life sciences, food and feed, pharmaceutical, environmental and chemical fields.

What are the different types of laboratory crucibles?

Depending on the operation and the chemistry involved, select the shape, material and volume. High-form crucibles minimise splash losses; low-form versions promote evaporation. A lid is helpful for controlled ignition. Gooch types (sintered glass/silica or porcelain base) are used in gravimetry with built-in filtration.

• Porcelain: cost-effective, good thermal stability (? 1 050–1 200 °C), durable glaze. Avoid HF and prolonged exposure to molten bases.
• Alumina (Al?O?): highly chemically inert, manages thermal shock, up to ? 1 600–1 700 °C depending on grade.
• Quartz/silica: excellent thermal-shock resistance, ? 1 050–1 100 °C; incompatible with HF/fluorides.
• Platinum / Pt–Au alloy: ultra-clean, ideal for borate fusions and Pharmacopoeia ROI; the Pt–Au alloy reduces flux sticking.
• Nickel: robust for alkaline/peroxide fusions; avoid oxidising acids.
• Vitreous carbon / graphite: very high T under inert atmosphere; oxidises in hot air.
• PTFE: chemically resistant (HF), low temperature (? 260 °C) for gentle digestions.

Selection criteria:
• Service temperature and heating ramps (muffle furnace, flame, microwave).
• Chemical compatibility (acids, bases, fluxes, oxidants).
• Background purity (metal traces), constant mass for gravimetry.
• Shape, capacity, lid, sintered base (Gooch).

Quick comparison table:

Type	Principle	Applications
Porcelain	Vitrified ceramic, good thermal stability	Ashing, ROI, routine calcination
Alumina	High-purity aluminium oxide	High-T calcination, materials, catalysis
Platinum / Pt-Au	Noble metal, anti-wetting surface	Borate fusions, XRF, trace analysis
Nickel	Alloy reactive to oxidising acids	Alkaline, peroxide fusions
Quartz/silica	Vitreous, low expansion	Thermal-shock scenarios, clean ashing
PTFE	Low-T inert polymer	Acid digestions incl. HF, pre-treatments

In short: favour alumina for high temperature, porcelain for economy, platinum for ultra-clean work, nickel for basic fusions, and PTFE for HF digestions.

In which fields is a crucible used?

• Food and feed: determination of ash content and loss on ignition (LOI) in foodstuffs, additives and packaging.
• Pharmaceuticals & cosmetics: residue on ignition (Ph. Eur./USP), excipient purity control, filter calcination.
• Environment: volatile matter and ash in sludges, deposits and soils; mineralisation prior to analysis.
• Chemistry & materials: borate fusions for XRF, alkaline/peroxide fusions, solid-state synthesis, calcination of precursors.
• R&D: development of thermal treatments, TGA/DSC studies with suitable micro-crucibles.
• Quality control: validation of thermal processes and thermal stability of finished products.

Across applications, the material/atmosphere pairing (air, inert gas) and the thermal profile are critical for reliable, reproducible results.

Available crucible types

Crucible

Frequently asked questions about laboratory crucibles

What’s the difference between porcelain and alumina crucibles?
Porcelain is cost-effective and withstands ? 1,100 °C. Alumina offers high purity and service up to ? 1,700 °C, ideal for high temperatures and demanding chemistries.

Which crucible should I choose for a borate fusion (XRF)?
A platinum or Pt–Au crucible minimises wetting by the flux and delivers a very low blank. Avoid nickel/steel, which contaminate and deteriorate.

Are quartz crucibles suitable with hydrofluoric acid (HF)?
No. Quartz and glass are attacked by HF. Choose a PTFE crucible for low-temperature digestions involving HF.

How can I prevent cracks from thermal shock?
Ramp temperature up and down in steps, preheat gently, avoid sudden transfers from cold air to a hot furnace, and use suitable supports.

When should a Gooch crucible be used?
For gravimetric analyses with integrated filtration (sintered base). Filter, dry/ignite, then weigh directly without transferring.

How do I care for a platinum crucible to extend its life?
Avoid molten metals and aggressive halides, clean using suitable baths, store separately, and straighten the walls without heavy abrasion.