Mortar and Pestle: Uses and How to Use It

Laboratory equipment guide

Mortar and Pestle: Uses and How to Use It

A mortar and pestle are a grinding pair: the mortar is a thick bowl and the pestle a club-shaped rod. They are used to crush solids or crystals into powder and to mix powders evenly.

How to use a mortar and pestle Mortar and Pestle at AMI Scientific

What is a mortar and pestle used for?

Grinding crystals or solids into fine powder.
Mixing two or more powders evenly.
Preparing samples, e.g. KBr pellets for FTIR or pharmaceutical preparations.

Parts of a mortar and pestle

1Pestle – the grinding rod with a rough end
2Mortar – a thick bowl, usually unglazed inside for grip

How to use a mortar and pestle

Step 1

Add only a little

Add no more than a third of the mortar's depth (1). Small amounts grind faster and do not fly out.

Step 2

Grind with a pressing, circular motion

Hold the mortar with one hand and move the pestle in circles while pressing down (1). Pound only to break large lumps, and gently.

Step 3

Transfer the powder with a spatula

Scrape the powder from the mortar walls with a spatula and transfer it to a watch glass or labelled bottle (1).

Common mistakes

Grinding oxidisers together with organics or sulfur (e.g. potassium chlorate with sugar): it can explode.
Pounding a porcelain mortar hard: it cracks or chips.

Care and safety

Wash and dry after use; stubborn residue can be removed by grinding a little clean sand or salt, then rinsing.
Keep separate mortars for analytical samples and for rough materials to avoid contamination.

SOP for using a mortar and pestle

A summary of the standard operating procedure (SOP) for a mortar and pestle that your laboratory can adapt. Each step is explained in the how-to section above.

1Protective equipment

A buttoned, long-sleeved lab coat.
Safety glasses; goggles where corrosive splashes are possible.
Nitrile gloves suited to the chemicals handled; heat-resistant gloves for hot items.
A dust mask when grinding fine or toxic powders.

2Before use

The mortar and pestle are clean, dry and uncracked.
Read the SDS of every chemical you will handle.
Make sure substances ground together do not react (never combine oxidisers with organics, sulfur or metal powders).

4After use

Transfer the powder to a labelled container.
Wash, rinse with distilled water and dry.

5Verification & calibration

Not calibrated; check for cracks and residues before use.

6Emergencies

Breakage: never pick up shards by hand. Use a brush and dustpan or tongs and put them in the broken-glass bin.
Chemical spill: warn people nearby, secure the area and clean up with a spill kit according to the SDS.
Chemical on skin or in eyes: rinse with running water for at least 15 minutes (eyewash or safety shower), then report to the lab supervisor.

A print-ready version with purpose, scope, illustrated procedure, verification and sign-off boxes. Fill in your own document number and effective date.

Download the SOP (PDF, A4)

Types and sizes

Porcelain mortars are most common, 50–200 mm in diameter. Agate mortars are very hard and used for analytical samples that must not be contaminated; glass mortars for coloured substances; iron mortars for very hard materials.