Bob Yandell – Mortar and Pestle

Club Meeting: 5 June 2024
Report by: Kieran Fitzgerald

Our demonstrator tonight was Bob Yandell. Bob began with an interesting introduction about the history of the mortar and pestle. These are one of the oldest tools invented by humankind, being in existence since the stone age, so over 10,000 years ago. When it was required to grind or crush seed to make food they used an indented stone as a base, and mallets of stone or wood to process their plants and other foods.

Earlier in the evening, Jim Jackson had shown us a weapon that he was gifted as a child by the Maasai people, and was deployed to bring down a lion. Bob pictured the Maasai using a wooden jar and a pole as a mortar and pestle to crush their grain.

Today the mortar and pestle are typically associated with the pharmacy profession due to their history in preparing medicines. The image of a mortar and pestle would be displayed outside the premises of pharmacy to provide a visual reference for those unable to read. They are used in chemistry to pulverize materials, used in the arts and cosmetics, and of course by chefs in the processing of seasonings.

The mortar is a simple bowl with size determined by the user and the ingredients to be ground or pulverized. It is either held in the palm of the hand or sits on the work bench.

The pestle is a simple mallet that fits inside the mortar and can be easily held in one hand. Early pestles could be up to a metre or more in length requiring two hands to hold.

Bob showed us an example of a stone mortar and pestle used for preparing seasonings. In woodturning the size and shape is a personal choice.

The Pestle

You want a hard wood. Bob’s demo pestle is olive, and he has used pohutukawa in the past. Bob joined the olive to a pohutukawa blank with a glued dowel joint, providing an attractive two tone pestle once turned to shape.

The total starting length of the blank is approx 170mm.

The blank is turned between centers with a 30mm chuck in the headstock and a steb live centre in the tailstock. Initial rounding is achieved with the spindle roughing gouge and final shape is created using skew and spindle gouges. The olive end is rounded to 25 – 28mm with a profile not to dissimilar to that of the end of the steel rules used in the club. The end is sanded smooth. The handle end reduces to 20mm, with an overall length of 95 – 100mm.

The hand end of the pestle can be a personal choice based on looks and comfort, and the grinding end should be a “fit” with the internal shape of the mortar.

The Mortar

The key elements of this simple bowl that make it suitable for a mortar are as follows:

It can be held in the palm of the hand or be stable on the bench.

It is deep enough

It has a slightly concave inside wall and a curved base/floor to retain and grind the product being processed

The wall thickness, at least 10mm, is such that it can survive the pulverizing action

The bowl material needs to be of a hard wood. Bob used olive. Pohutukawa is also suitable. Puriri is not suitable as the colour, yellow, will taint the product being processed.

The blank is 95 x 75 and mounted using a screw chuck. The spigot is 46mm x 8mm and will be turned off when the inside is complete. The external curve of the bowl is hand friendly. Remember to indicate the centre of the spigot to ease alignment for removal of the spigot.

Remount on the spigot and hollow. Wall thickness is 10mm and a slight undercut inside wall. As when turning a hollow form the shavings are caught up inside and this is what you want to happen to the product being ground/crushed. The profile of the internal base should allow even contact with the pestle. A heavy bottom is desirable.

The inside bottom of the mortar needs to have some roughness to grind herbs and spices against, so 80 grit sandpaper will suffice.

The mortar can be mounted to allow the spigot to be removed:
Against a faceplate
Using a vacuum chuck
Using the 50mm chuck in expansion if it suits.

Our thanks to Bob for demonstrating this utilitarian tool which should be both a useful and attractive adornment in every kitchen.