Silvopasture and Agroforestry

Processing walnuts: removing the hulls

I’ve spoken before that a byproduct of processing walnuts can be used to tan animal hides. Walnut hulls are green when they fall from the tree and quickly turn black. Pulp in between the hull and nutshell as well as the hull itself all contain large amounts of tannic acid which is water soluble.¬†Soaking hides with walnut hulls in water preserves the hides as well as providing dye of the beautiful deep brown common to all things walnut.

This is the step where nitrile gloves are required if you want to avoid tanning your own hide. Trust me on this, the dye cannot be removed and will persist until your skin naturally replaces itself. I tanned my own hands by using cotton work gloves that had been dipped in rubber. Clearly, they did not provide enough protection:



To loosen the hulls, I use an antique corn sheller. Other methods commonly used are: driving over intact fruit with a vehicle or more dangerously, setting a vehicle on blocks and spinning tires over walnuts; manual removal with a nut cracker or vise; another dangerous method is injecting compressed air via a needle into the hull.

I chose the corn sheller because it is pretty easy, my uncle has one, it is only moderately dangerous and plays into my love of antique machinery:


With my machine:

  • Load the hopper with intact nuts
  • Set buckets under the machine to catch hulls and another to catch dehulled nuts
  • Spin the handle to build up momentum in the gears
  • Let walnuts drop into the sheller one by one
    • Very frequently, I must turn the flywheel manually as the nut stops the motion and it is the only safe way to stick my hand into dangerous equipment to push the nut through
    • Every 5 gallon bucket, I use a screwdriver to reach in and clean the teeth of the sheller. With walnuts this fresh, they tend to clog the teeth with gunk.
  • Hand clean the remaining hulls from the nuts
    • put the hulls in a larger container for storage
    • do the same for finished nuts

A lot of people then wash the nuts with high pressure water. I just make an effort to move on to the next step soon after. That next step is cracking and extracting the edible meat of the nuts!