Updated April 2021
Walnut shells are a versatile abrasive media widely used in blasting, tumbling, cleaning, polishing, filtration, cosmetics, as well as non-skid applications and filler applications. Walnut shells are crushed, ground and classified to standard mesh sizes that range from coarse grio fine powders.
There are two varieties of ground Walnut Shells produced: standard-grade English Walnut Shell (juglans regia) and filtration-grade Black Walnut Shell (juglans negra).
This article provides an overview of walnut shell uses and applications.
Characteristics of Crushed Walnut Shells
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Figure 1. Walnut shell blasting media
Walnut shell media (Figure 1) is an all-natural, biodegradable, durable material with excellent strength characteristics. It has a specific gravity of 1.2-1.4 and a hardness of 3.5 MOH and 91 Rockwell.
Walnut shell performs well in a variety of pH and temperature conditions and are resistant to fermentation. They are reusable and reclaimable and thus serve as a suitable blast media in outdoor applications. Composition Materials has supplied walnut shell products globally for over 60 years.
Walnut Shell Blasting
In walnut shell blasting, wheel blast or air blast equipment is used to remove paints and coatings from buildings, cars, boats, furniture, fiberglass, steel, etc.
Walnut shell blasting offers the aggressiveness required to remove hard paints and coatings without damaging substrates. The process also enables selective coating removal, wherein the top coating can be removed without affecting the underlying coatings.
In blast operations, a number of factors are involved and they include safety, nozzle distance, media particle size, and p.s.i. Walnut shell blasting does not cause silicosis and hence provides a perfect alternative to sandblasting.
Walnut Shells for Deflashing, Polishing & Tumbling
Walnut shells are also used to deflash parts, as well as for tumbling and polishing brass, metal, plastics and hard rubber. In tumbling applications, a polishing compound is often mixed with the walnut shells.
Walnut Shell Fillers
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Figure 2. Walnut shell flour
Ground walnut shell grits and flours are made for the construction, furniture, adhesives, paint, plywood, resin, rubber, paint and cosmetic industries. For anti-slip applications, ground walnut shell serves as a suitable additive for stairs, decks, pools, floors, and ramps. In addition, walnut shell flour is a preferred additive in rubber and plastics compound manufacturing. Moreover, walnut shells are employed in burn-out applications to improve porosity in ceramics.
Walnut Shell for Filtration
Figure 3. Black walnut shell filtration media
The Black Walnut variety (juglans negra) has an extremely hard shell with characteristics that make it an ideal media in filtration operations. For example, Black Walnut Shell offers excellent filtration solutions in oil fields for separating oil or solids from water.
Walnut Shells in Cosmetics
Walnut shells are used in a variety of body and bath products, hand soaps and scrubs. This all-natural, biodegradable ingredient is an excellent microbead replacement and has been used in cosmetic formulations for over 30 years. Cosmetic services include sterilization and custom packaging.
This information has been sourced, reviewed and adapted from materials provided by Composition Materials.
For more information on this source, please visit Composition Materials.