How to Clean and Maintain Your Mortar and Pestle

A well-maintained mortar and pestle can serve your kitchen for decades—even generations. However, improper cleaning can damage the grinding surface, introduce unwanted flavours into your food, or even compromise food safety. Understanding how to care for your specific type of mortar and pestle is essential knowledge for any serious home cook.

General Cleaning Principles

Before diving into material-specific guidance, there are universal principles that apply to all mortar and pestle types:

• Clean immediately after use: Fresh residue is always easier to remove than dried-on particles
• Avoid thermal shock: Never expose a mortar that's been grinding hot ingredients to cold water suddenly
• Dry thoroughly: Moisture can lead to mould, bacterial growth, or material degradation
• Store properly: Keep in a dry location with good air circulation

Cleaning Stone Mortars (Granite, Basalt, Volcanic Stone)

Stone mortars, including popular granite and traditional volcanic stone molcajetes, are the most common and durable type. Their porous nature requires special attention to prevent flavour absorption and ensure hygiene.

Routine Cleaning Method

1. Scrape out any large particles using a wooden spoon or the pestle itself
2. Rinse under warm running water
3. Use a stiff brush (a dedicated vegetable brush works well) to scrub the interior surface
4. For stubborn residue, add a small amount of uncooked white rice and grind to absorb oils and particles
5. Rinse thoroughly and shake off excess water
6. Air dry completely—ideally overnight before storing

Deep Cleaning for Strong Flavours

After grinding particularly pungent ingredients like chillies, garlic, or strong spices, you may need a deeper clean:

• Grind a paste of raw white rice with water until the rice no longer picks up colour or scent
• For persistent odours, create a paste with baking soda and water, let sit for 15 minutes, then scrub and rinse
• Sun-drying can help neutralise odours naturally—place the clean, wet mortar in direct sunlight for several hours

Cleaning Marble Mortars

Marble requires gentler treatment than granite due to its calcium carbite composition, which can react with acids and etch easily.

Recommended Cleaning Process

1. Wipe out loose particles with a dry cloth
2. Rinse with warm water—never hot, as temperature changes can crack marble
3. Use a soft brush or cloth to clean (avoid stiff bristles that can scratch the polished surface)
4. Dry immediately with a soft towel to prevent water spots

Cleaning Wooden Mortars

Wooden mortars, common in Thai and some South American cuisines, require unique care to prevent cracking, warping, and bacterial contamination.

Proper Wood Care Routine

1. Wipe out all food particles immediately after use
2. Rinse briefly under cool water—never soak wooden mortars
3. Scrub gently with a soft brush if needed
4. Dry immediately and thoroughly with a clean towel
5. Store upside down to allow any remaining moisture to escape

Conditioning Wood

Every few months (or when the wood appears dry), condition your wooden mortar:

• Apply food-safe mineral oil with a soft cloth
• Let absorb for several hours or overnight
• Wipe off excess oil
• Never use vegetable oils, which can turn rancid

Cleaning Ceramic Mortars

Ceramic mortars are the easiest to clean because they're non-porous when properly glazed.

Simple Cleaning Steps

1. Rinse under warm water
2. Use mild dish soap if desired—ceramic can handle it
3. Scrub with a brush or sponge
4. Rinse thoroughly and dry
5. Many ceramic mortars are dishwasher safe—check manufacturer guidelines

Maintaining the Grinding Surface

Over time, the grinding surface of any mortar can become too smooth to function effectively. Here's how to maintain optimal texture:

For Stone Mortars

• Periodically grind coarse salt or uncooked rice to refresh the surface texture
• If severely smoothed, very carefully roughen with coarse sandpaper (only as a last resort)

Prevention Tips

• Don't grind excessively oily ingredients repeatedly without cleaning between uses
• Avoid polishing the interior with oil or wax
• Use the full surface area, not just the centre, to promote even wear

Long-Term Storage

If storing your mortar and pestle for extended periods:

• Ensure completely dry before storing
• Store in a well-ventilated area, not in sealed containers
• For wooden mortars, apply mineral oil before long-term storage
• Consider covering with a clean cloth to prevent dust accumulation
• Store pestle separately to prevent accidental impact damage

Common Mistakes to Avoid

Even experienced cooks sometimes make these care errors:

• Soaking stone mortars: Extended water exposure can cause cracking or surface damage
• Using bleach or harsh chemicals: These can be absorbed by porous materials and are difficult to remove completely
• Machine washing stone or wood: The heat and agitation can cause irreparable damage
• Storing while damp: Creates conditions for mould and bacterial growth
• Stacking heavy items on top: Can crack or chip the mortar

Conclusion

Proper care and maintenance of your mortar and pestle is a small investment of time that pays significant dividends. A well-maintained grinding set will perform better, last longer, and remain safe for food preparation. By following the material-specific guidelines outlined here and establishing a regular maintenance routine, your mortar and pestle can become a treasured kitchen heirloom passed down through generations of enthusiastic home cooks.