Congratulations on your new mortar and pestle! Before you start grinding spices and making pastes, there's an important step that many new owners skip: seasoning. Unlike cast iron seasoning, which creates a non-stick surface, mortar seasoning removes manufacturing residue, loose stone particles, and grit that would otherwise end up in your food. This process is essential for any new stone mortar—skipping it risks contaminating your first several dishes with unpleasant gritty particles.

⚠️ Don't Skip This Step

Using an unseasoned stone mortar will introduce stone grit and dust into your food. The first few grinding sessions will produce noticeably gritty results, and that contamination is exactly what seasoning prevents.

Why Seasoning Is Necessary

When stone mortars are carved and finished, the process creates loose particles on the grinding surface. These particles—ranging from microscopic dust to visible grit—are unavoidable by-products of the manufacturing process, even in high-quality mortars. Additionally, the surface may contain residue from the carving tools or polishing compounds used during production.

Seasoning accomplishes several important goals:

  • Removes loose particles: Grinding rice dislodges and captures surface grit
  • Smooths microscopic roughness: Creates a more uniform grinding surface
  • Removes manufacturing residue: Any oils or compounds from production
  • Prepares the surface: Opens the stone's texture for optimal grinding performance

Materials Needed

The seasoning process requires minimal materials:

  • Uncooked white rice (approximately 2-3 cups total)
  • Water for rinsing
  • Stiff brush or scrubbing pad (for initial cleaning only)
  • Clean towels for drying

đź’ˇ Pro Tip

Use inexpensive long-grain white rice for seasoning—there's no benefit to using expensive varieties since the rice will be discarded. Avoid instant rice, which doesn't have the right texture for this purpose.

Step-by-Step Seasoning Process

Step 1: Initial Rinse

Begin by rinsing your new mortar and pestle under warm water. Use a stiff brush to scrub the entire interior surface of the mortar and the grinding end of the pestle. This removes any visible dust or debris from packaging and shipping.

Important: Do not use soap or detergent during this rinse. Stone is porous and will absorb soap residue, which is very difficult to remove and will affect the taste of your food.

Step 2: First Rice Grinding

  1. Add approximately 1/4 cup of dry white rice to the mortar
  2. Grind the rice with moderate pressure using the pestle
  3. Work in circular motions, covering the entire interior surface
  4. Continue grinding until the rice is pulverised to powder (3-5 minutes)
  5. Observe the colour of the ground rice—it will likely be grey or brownish

🔑 Key Indicator

The colour of the ground rice tells you about grit levels. Grey or brown rice indicates stone particles are still releasing. You're finished seasoning when ground rice remains white.

Step 3: Discard and Repeat

  1. Discard the ground rice (it contains stone dust—do not eat)
  2. Rinse the mortar thoroughly with water
  3. Add fresh rice and repeat the grinding process
  4. Continue this cycle until the ground rice remains white

Most quality mortars require 4-8 grinding sessions before the rice stays white. Cheaper mortars or those made from softer stone may require more. Be patient—this is a one-time investment in food safety.

Step 4: Final Cleaning

Once your rice grinds white:

  1. Rinse the mortar and pestle thoroughly
  2. Allow to air dry completely—this may take several hours or overnight
  3. Your mortar is now ready for food preparation

Seasoning Different Stone Types

Granite

Granite typically requires 4-6 rice sessions. It's a relatively hard stone, so the process is straightforward and the mortar seasons efficiently.

Volcanic Stone (Molcajete)

Traditional Mexican molcajetes require the most extensive seasoning—often 8-12 or more rice grinding sessions. The vesicular (porous) nature of volcanic rock means more loose particles and deeper pores that trap grit.

Some sources recommend following rice grinding with grinding a mixture of garlic, cumin, and salt to begin building flavour into the stone. This is optional but creates a foundation layer that enhances future preparations.

Marble

Marble requires minimal seasoning—usually 1-2 sessions—as it has a smoother, less porous surface. Some marble mortars may not require any seasoning if they're well-finished.

Ceramic

Glazed ceramic mortars don't require seasoning at all. Simply wash with soap and water before first use. Unglazed ceramic may benefit from a single rice-grinding session.

⚠️ Wood Mortars

Wooden mortars are not seasoned with rice. Instead, condition them by rubbing with food-safe mineral oil, allowing it to absorb overnight, then wiping off excess. Repeat 2-3 times before first food use.

Alternative Seasoning Methods

Garlic and Salt Method

Some traditions recommend seasoning with garlic and coarse salt instead of or after rice:

  1. Grind 4-5 cloves of garlic with 2 tablespoons of coarse salt
  2. Work the paste over the entire surface
  3. Allow to sit for several hours or overnight
  4. Rinse thoroughly and dry

This method both seasons the surface and begins imparting flavour into the stone—traditional for molcajetes used primarily for savoury preparations.

Combined Method

For the most thorough seasoning:

  1. Complete the rice grinding process until rice stays white
  2. Follow with the garlic and salt method
  3. Rinse, dry, and your mortar is fully prepared

Signs Your Mortar Needs Re-Seasoning

Over time, or after particularly intense use, you may need to re-season your mortar:

  • You notice grit in your ground preparations
  • You accidentally used soap and want to remove residue
  • The mortar has been unused for years and collected dust
  • You want to remove persistent flavours (e.g., switching from spicy to mild use)

âś… Well-Seasoned Signs

A properly seasoned mortar will produce clean-tasting food with no gritty texture. The grinding surface should feel smooth to touch (though still textured enough to grip ingredients) and show no visible loose particles when rubbed.

Common Seasoning Mistakes

Using Soap

Soap molecules bind to porous stone and are very difficult to remove. If you accidentally used soap, you'll need extended rice grinding (possibly 10-15 sessions) to remove the taste, or the mortar may permanently retain a soapy flavour.

Rushing the Process

Don't decide "good enough" after two or three sessions if the rice is still grey. The contamination will end up in your food. Complete the process properly once, and you'll never have to worry about it again.

Insufficient Grinding Pressure

Light grinding won't dislodge embedded particles. Use firm, steady pressure throughout the seasoning process—treat it like actual food grinding rather than gentle polishing.

Not Covering the Entire Surface

Ensure your grinding motions cover the entire interior of the mortar, including up the walls and the base. Neglected areas will remain unseasoned and release grit during future use.

After Seasoning: First Uses

Once seasoned, your mortar is ready for food preparation. For your first few uses:

  • Start with dry spices rather than wet preparations—this continues the seasoning process
  • Pay attention to any grit in your first grinds; if present, do another rice session
  • Clean properly after each use (warm water, stiff brush, thorough drying)

Conclusion

Seasoning your new mortar and pestle is a crucial step that ensures food safety and optimal performance. While the process requires patience—especially for volcanic stone molcajetes—it's a one-time investment that prepares your tool for years or decades of reliable service. Take the time to do it properly, and your mortar will reward you with clean, grit-free grinding from the very first culinary use.