Buchner Funnels, Porcelain, With Sintered Disc

Quick Answer: A porcelain Buchner funnel with sintered disc is a white ceramic suction-filtration funnel whose filter plate is a porous, fused ceramic disc instead of a perforated plate covered with paper. It is used on a filtering flask to separate solids from liquids, particularly hot or chemically aggressive mixtures.

Ceramic Body, Porous Plate

Porcelain has long been the traditional material for Buchner funnels because it is rigid, copes well with heat and resists most acids. The version described here replaces the usual pattern of holes with a porous plate made by sintering ceramic particles, so the plate itself retains the solid. Suction from below draws the liquid through the pores, and the solid collects as an even cake across the plate.

Compared with a sintered glass funnel, porcelain is opaque, so the condition of the plate can only be judged from above. It is heavier, stands up well to the knocks of a busy washing-up area, and glazed porcelain handles hot filtrations comfortably. Like glass, it is attacked by hydrofluoric acid and by hot concentrated alkalis, which dissolve the glaze and open up the pores.

Porcelain Buchner funnels are also widely sold with a perforated plate for use with paper, under very similar names. The title here says sintered disc, but confirm the plate type, porosity and diameter when ordering, especially if your method was written for paper. The sintered glass Buchner funnel is the transparent alternative, and either funnel fits a filtering flask on a rubber cone or bung.

Care & Handling

• Warm the funnel before a hot filtration and cool it slowly afterwards; porcelain resists heat but can crack if a cold funnel meets boiling liquid.
• After use, draw water through from below as well as from above to flush particles out of the pores.
• Soak stubborn inorganic deposits in dilute hydrochloric acid, then rinse thoroughly before drying.
• Check the rim and stem for chips before fitting the funnel, because a chip can break the vacuum seal.

Applications

• Hot suction filtration of mixtures that would crystallise on a cold funnel, with the porcelain pre-warmed in an oven
• Collecting inorganic precipitates and washing them free of soluble salts
• Separating solids from acidic leach solutions in materials and mineral laboratories
• Dewatering filter cakes of pigments, clays or soil samples in student projects

Specifications

Why Choose LabEquip

Materials, mineral and inorganic chemistry labs often choose porcelain where funnels face heat and heavy daily use. LabEquip lists this funnel in its chemistry lab equipment collection; tell us the plate type and diameter your procedure needs through the contact page.

Frequently Asked Questions

How is a sintered porcelain plate different from a perforated one?

A perforated plate has visible holes and needs a filter paper laid over it to catch the solid. A sintered plate is itself porous, so the solid is retained on the ceramic surface and no paper is required.

Is porcelain or sintered glass better for my filtration?

Glass lets you see the disc and is easier to inspect for blockage. Porcelain is opaque but rugged and handles hot mixtures well. Both are attacked by hydrofluoric acid and hot alkali, so the choice usually comes down to visibility versus robustness.

How should the funnel be sealed to the flask?

Use a rubber cone or a bored bung that fits the stem snugly and sits in the flask neck. Moisten the rubber slightly to seat it. A leak at this joint is the most common reason for weak suction.

Can I put the funnel in a drying oven?

Yes, porcelain tolerates oven drying well. Let it cool in the oven or on a heat-resistant mat rather than rinsing it while hot, because sudden cooling is what cracks ceramic ware.

Why does the filtrate come through cloudy at first?

The first portion may carry very fine particles that pass the pores before a cake forms. Pour the cloudy filtrate back through once a thin layer of solid has built up on the plate; the cake then acts as an extra filter.

How do I remove a precipitate that has lodged in the pores?

Choose a solvent or dilute acid that dissolves it and pull it through the plate under gentle suction, then flush with water from the stem side. Avoid scraping the plate with metal tools, which can damage the surface.

Last Updated: September 2026