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Making a Large mortar and pestle

Whether you want to make a small mortar and pestle or a large African style version, burning the mortar cup out using hot coals is an effective method. This technique can also be used for making many kinds of other utensils too. If you don't have a spoon knife or just want to get more primitive then this is the answer.

Since making this mortar and pestle a few years ago I have used it countless times as part of processing many types of foraged seed and nuts into food, particularly Pendulous Sedge seed and Acorns. It has also come in handy for grinding tannin rich materials such a Oak galls, Walnut husks and many types of tree bark which I use for tanning skins.
 


Start out with a log of hardwood, I am using Oak, it is important that the wood is completely seasoned otherwise it would likely split severely as it dries. (If you wish to prepare food in your finished mortar be sure to use a non-toxic wood.) Removing the bark can be a good idea as this can harbour wood eating beetle larvae. Any undulations in the log's shape can also be rounded off using a sharp hatchet, as I did. Make sure the top and bottom are cut nice and level too.
 


As a starting point and also to help the hot coals get a purchase on the wood use a knife make a small depression in the centre.
 


Before we get burning you'll need some kind of straw through which to blow air at the hot coals. Encouraging the burn rate in this way is essential. A straw can easily be fashioned from a stem of Elder by pushing the pith out, a stiff piece of fencing wire can be used to do this, alternatively it could be rodded/ drilled out with a thin shoot of wood such as Willow. (for safety reasons I have to state that Elder wood is classed as mildly poisonous, but personally it does not concern me using it as a straw in this way).

A large pair of tweezers will make life easy when transferring coals from the fire to your log. A small wedge bound between two flexible pieces of flat wood does the job for this.
 


Start your fire and you are all ready to go
 

 

 

 

 

 

 

 

Take some good coals from the fire and place in the depression, now blow on them...
 


Keep blowing air until you make your first good depression. You may notice that progress will slow down due to an eventual build up of thick charred wood. At this point remove the coals.
 

Scrape out the build up of charcoal with a stick. Then add more coals and continue to burn the mortar cup bigger.
 


On a large project like this I decided to save my lungs a lot of effort and make a pair of bellows. This is a much faster method if you have the materials. The bellows can be made from some scrap plywood, and leather. I guess heavy duty canvas or similar material could be used. For the pipe on the end I started with a piece of bamboo but later changed this for a long piece of copper pipe. staple and nail the whole thing together for a quick but effective job.


Constant burning and scraping is the name of the game. Keep going until the mortar cup is as big as you'd like

Some areas will probably burn faster than others which creates thin and thick areas. You can protect the thin areas from further burning by protecting them with clay.
 

When the mortar cup is the desired depth and size give it a good scrape out with a crook knife and give the outside a final shape with a draw knife.
 


The large pestle is easy enough to make. Take a similar hard wood stave, thin it down in the middle, leave the bottom nice and hefty. Round the grinding end off nicely with your knife. All ready to grind!


Selection of mortars. Smallest pairs up with a nice Quartzite stone that I found in an arable field.

 

Have fun!