Which mortar and pestle material should a laboratory use?

Match the material to the sample and to what you will measure afterwards. Agate is the general-purpose choice for trace analysis because it is extremely hard, chemically inert and contributes almost no contamination when it is ground. Porcelain and ceramic are cheaper, fine for routine sample preparation and soil work, but the glaze can chip and the body is porous where the glaze is worn. Stainless steel suits hard, coarse materials and field work but sheds iron, chromium and nickel, which makes it unsuitable when you are measuring metals. Boron carbide and tungsten carbide are used where extreme hardness is needed and a small amount of wear is acceptable.

How do I pick the right mortar capacity for my samples?

Work from the largest single sample you will grind, not from the average. Fill the bowl to no more than about one third with sample so the pestle has room to move and material does not spill over the rim; a 100 millimetre bowl therefore handles roughly 30 to 50 grams of dense material and considerably less of a light, bulky powder. If you routinely grind a few hundred milligrams for infrared or X-ray work, a small 50 to 60 millimetre agate set gives better control than a large bowl. Many laboratories keep one small set for spectroscopy and one larger set for bulk preparation.

How should a mortar and pestle be cleaned between samples?

Grind a small quantity of the next sample or a suitable scrub material first, then discard it, so the surface is conditioned before the sample you keep. Wash with warm water and a mild neutral detergent, using a soft brush rather than an abrasive pad, and rinse with distilled or deionised water. Agate and ceramic should be air dried, never heated, because thermal shock will crack them. For trace metal work, follow the water rinse with a dilute acid rinse and a final water rinse, and keep a separate set dedicated to that work. Never mix a mortar used for soils with one used for food or pharmaceutical samples.

Can a mortar and pestle be used for cryogenic or wet grinding?

Yes, with care. Wet grinding with a small volume of an inert solvent such as ethanol or hexane reduces dust, limits heating and produces a finer, more uniform particle size, which matters when the sample is heat sensitive. For cryogenic work, chill the mortar and pestle in liquid nitrogen or a freezer and grind the sample while it is brittle, but never pour liquid nitrogen into a warm ceramic bowl or handle it in a closed room without ventilation. Add the cryogen slowly, keep the bowl supported, and use tongs or insulated gloves rather than bare hands.

Mortar and Pestle Singapore

Published: {{NEW_ARTICLE_DATE}} | By JWRESEARCH | Category: Laboratory Equipment

Grinding is the step that decides the quality of everything after it. A sample that is ground to an uneven particle size will digest unevenly, extract unevenly and read inconsistently, no matter how good the instrument is. When the right mortar and pestle is not on the bench, people substitute a blender or a hammer mill and inherit the contamination and heat that come with it.

At JW RESEARCH SUPPLY, we supply laboratory mortars and pestles to contract laboratories, universities and industrial customers across Singapore. This guide covers the bowl materials, how to size the set to your sample, and how to clean and store it so the surface stays fit for trace work.

Bowl Materials Compared

Material	Hardness / Composition	Typical Capacity	Best For
Agate	Natural quartz, Mohs ≈ 6.5–7	50 – 200 mm bowl	Trace analysis, spectroscopy, low contamination
Porcelain / ceramic	Glazed body, Mohs ≈ 6–7	60 – 200 mm bowl	Routine grinding, soils, general sample preparation
Stainless steel	AISI 304 / 316, Mohs ≈ 5.5	80 – 200 mm bowl	Hard, coarse material, field and plant work
Boron carbide	Mohs ≈ 9.3	50 – 150 mm bowl	Very hard minerals, abrasives, alloys
Tungsten carbide	Mohs ≈ 9, metal binder	50 – 150 mm bowl	Extreme hardness where slight wear is acceptable

Specification Reference

Parameter	Typical Value	Notes
Standard bowl diameters	50, 60, 80, 100, 130, 150, 200 mm	80–100 mm covers most preparation benches
Sample fill level	≈ one third of bowl volume	Leaves room for pestle travel and mixing
Pestle head form	Rounded, flat or bevelled	Flat heads work faster on friable material
Achievable particle size	≈ 1 – 100 µm by hand	Longer grinding gives finer, more uniform powder
Heat resistance	Agate and ceramic: no direct heating	Thermal shock is the main cause of cracking
Chemical resistance	Agate and ceramic: inert to most acids	Avoid hydrofluoric acid and hot alkali

Sizing the Set to the Sample

Start with the largest sample you realistically need to process in one go, then choose a bowl that holds roughly three times that volume. A bowl filled to the rim cannot mix: the pestle pushes material over the edge instead of working it against the wall, and the fines you do produce are uneven. For a 20 gram soil sample a 100 millimetre bowl is comfortable; for a few hundred milligrams destined for infrared or diffraction work, a 50 millimetre agate set gives far better control and less material loss.

Think about contamination at the same time as capacity. Stainless steel is tough and inexpensive, but it releases iron, chromium and nickel into the sample, which rules it out when those elements are the analytes. Porcelain is a good middle ground until the glaze wears or chips, at which point the exposed body can adsorb and later release material. Agate costs more and must never be heated, but it stays inert and is the standard choice when the result depends on keeping the sample clean.

Grinding Technique on the Bench

Add material in small portions rather than all at once, and grind with a light circular pressure around the bowl wall instead of striking downwards. The aim is abrasion, not impact: a grinding action produces a uniform powder, while hammering cracks the bowl, heats the sample and throws dust. For heat sensitive material, grind in short bursts and let the bowl cool between them, or use wet grinding with a small volume of an inert solvent.

For very hard or brittle samples, chill the bowl and sample first so the material fractures rather than deforms. Handle liquid nitrogen with insulated gloves, in a ventilated space, and never pour it into a bowl that is at room temperature. Whatever the technique, keep a separate mortar for soils, for food or pharmaceutical samples, and for trace metal work; sharing one bowl between those categories is the fastest way to carry contamination from one project into the next.

Cleaning, Drying and Storage

Step	Action	Why It Matters
Condition	Grind and discard a little of the next sample	Removes residue and pre-loads the surface
Wash	Warm water, mild neutral detergent, soft brush	Brushes reach the bowl curve without scratching
Rinse	Tap water, then distilled or deionised water	Prevents dried water-spot contamination
Trace work	Dilute acid rinse, then final water rinse	Removes adsorbed metal ions
Dry	Air dry inverted, never on a hot plate	Heat cracks agate and crazes ceramic glaze

Store mortars and pestles as matched sets with the pestle inside the bowl, in a dry cabinet or a lined drawer, sorted by material and marked with the application they are reserved for. Check bowl interiors for chips, star cracks and worn glaze each time you clean them; a cracked bowl sheds fragments into the sample and cannot be repaired.

Ordering Checklist

Bowl material: agate, porcelain, stainless steel, boron or tungsten carbide
Bowl diameter and the largest sample you will grind in one pass
Pestle head form suited to friable or hard material
Wet grinding or cryogenic use, if the sample is heat sensitive
One small set for spectroscopy plus one larger set for bulk work
Storage that keeps matched sets together and free of chips

Tell us what you grind and what you measure afterwards, and we will match the bowl material, diameter and pestle form to your method, with spare sets and matched replacements held for local delivery.

Contact JWRESEARCH

JW RESEARCH SUPPLY — laboratory equipment and consumables, Singapore.
Telephone / WhatsApp: +65 8039 3660
Email: SINGAPORE@JWSHY.COM
Website: www.jwresearch.cn