Silica Crucible / Basin

Quick Answer: The Silica Crucible / Basin listing covers heating vessels made of fused (vitreous) silica: a small crucible for igniting and ashing samples and a shallow basin for evaporating solutions. A silica crucible withstands rapid heating and cooling far better than porcelain because fused silica expands very little with temperature.

Specifications

Fused Silica and Thermal Shock

Fused silica is silicon dioxide melted and cooled into a glass without the fluxes present in ordinary glass. Its coefficient of thermal expansion is extremely low, so one part of a vessel can be much hotter than another without building the stress that cracks porcelain or borosilicate. That is why silica ware can be heated strongly in a burner flame or furnace and set down on a cool surface with little risk of cracking. Opaque and translucent grades are generally made from fused sand, and clear grades from melted quartz; the grade supplied here is not stated.

Silica has clear limits. It is dissolved by hydrofluoric acid and attacked by hot concentrated phosphoric acid, and alkaline substances damage it, especially molten hydroxides and carbonates, so alkaline fusions belong in a nickel crucible instead. Held for long periods at very high temperature, fused silica can slowly devitrify, becoming cloudy and more fragile; traces of alkali from fingerprints encourage this, which is why silica ware is handled with clean tongs.

The listing names both a crucible and a basin, so state which form, and what capacity, is required. For routine evaporation at moderate temperature, the porcelain flat-form evaporating basin is the usual alternative.

Uses in the Laboratory

• Ashing food, plant or soil samples in a muffle furnace to measure ash or mineral content.
• Igniting precipitates to constant mass in gravimetric analysis.
• Heating hydrated salts to find the water of crystallisation.
• Evaporating acidic solutions to dryness in the basin before the residue is ignited.
• Loss-on-ignition tests on soils, cements and minerals.

Handling Silica Ware

• Handle with clean tongs or gloves; alkali and salts from skin promote devitrification at high temperature.
• Keep silica away from hydrofluoric acid, strong alkalis and alkaline fluxes.
• Cool ware on a clean heat-resistant surface rather than in water, and inspect it for cracks or cloudiness before each ignition.
• Clean with dilute acid or detergent and rinse well with distilled water; avoid abrasive scourers.

Why Choose LabEquip

Silica crucibles and basins are chosen by food, soil, cement and mineral-testing labs and by college analytical courses that ignite and ash samples at high temperature. LabEquip lists them with other heating ware in the General Lab Products range; specify form and capacity on the contact page.

Frequently Asked Questions

What is the advantage of silica over porcelain?

Fused silica expands very little when heated, so it resists cracking from rapid heating and cooling much better than porcelain. It also has no glaze, so there is no glaze layer to be attacked or to flake at high temperature.

Can silica crucibles be used for alkaline fusions?

No. Molten hydroxides, carbonates and peroxides dissolve silica, damaging the crucible and adding silicon to the sample. Use a nickel crucible for alkaline fusions.

Why has my silica crucible turned cloudy?

Long heating at high temperature can make fused silica devitrify, forming crystalline patches that look white and cloudy. Contamination by alkali, including fingerprints, speeds this up. Heavily clouded ware is weaker and should be replaced.

What is the difference between the crucible and the basin?

A crucible is a small, deep cup used to ignite, ash or melt samples, often with a lid. A basin is wider and shallower, giving a large surface for evaporating a solution before the residue is heated further.

Which acids attack silica ware?

Hydrofluoric acid dissolves silica rapidly, and hot concentrated phosphoric acid attacks it too. Most other acids, including hot nitric, hydrochloric and sulfuric acid, leave fused silica largely unaffected, which suits acid digestion work.

Can silica ware be placed straight into a hot furnace?

Fused silica tolerates sudden temperature changes far better than porcelain, so it is often placed directly into a hot furnace. Make sure it is clean and dry, since trapped water or residues can spatter, and handle it with tongs.

Last Updated: September 2026