* Cleansing and polishing: Walnut shells are mostly used to clean soft metals, fiberglass, plastics, wood and stone. Uses include cleaning automobile and jet engines, electronic circuit boards, and paint and graffiti removal. This soft grit abrasive is well suited for air blasting, de-burring, de-scaling, and polishing operations because of its elasticity and resilience. For example: In the early days of jet transportation, crushed walnut shells were used to scour the compressor airfoils clean, but when engines with air cooled vanes and blades in the turbine started being manufactured this practice was stopped. The problem being that the crushed shells tended to plug up the cooling passages to the turbine, resulting in turbine failures due to overheating.
* Oil well drilling: The shell is used widely in oil well drilling for lost circulation material in making and maintaining seals in fracture zones and unconsolidated formations.
* Paint thickener: Walnut shells are added to paint to give it a thicker consistency for “plaster effect” ranges.
* Explosives: Used as a filler in dynamite.
* Cosmetic cleaner: Occasionally used in soap and exfoliating cleansers
* Shells also make an excellent dye with no need for mortant. It can produce lovely browns ranging from light to dark browns. Many people have allergic reaction to walnuts.