Walnut Shell Powder

Walnut shell powder is a versatile ingredient with a harmonious light brown colour and a neutral smell.

What are Walnut Shell Granules?

Walnut shells are a by-product of walnut processing, mainly for the food industry. As walnuts are rich in polyunsaturated fatty acids, protein, B-vitamins and minerals (especially magnesium, manganese and potassium), they are grown in enormous volumes. The walnut production amounts to around 3.5 million tons per year with China being the largest producer. Significant quantities are grown in the United States, Romania, Mexico, Turkey, Iran and Spain.

A variety of the common walnut is the black walnut (botanical name: juglans nigra). It is native to North America and characterized by a particularly hard shell (hardness according to Mohs = approx. 4.5). Due to the inhomogeneous shape of the edible walnut, some remainders might stick to the shell, which leads to some oil content of the walnut shell powder. The granules have relatively sharp edges, however, scratching can be minimized by choosing a smaller grain size range.

Walnut Shell Abrasives in Various Industries

Its hardness of 3.5-4.00 according to Mohs scale makes walnut shells an effective natural abrasive in sandblasting, polishing and cleaning of hard materials such as metal, carbon fiber, concrete or hard plastic. This helps preserve and maintain industrial, medical and automotive equipment. Common examples of use can be found in aviation, where walnut shell granules are used for the cleanout of engines and turbines in an air jet blasting process. Besides, the biodegradable grit reliably removes corrosion or any chemical coating from boats, planes and buildings without the need for additives. It is also a bio-ingredient for hygiene products: especially in surface cleaners - above all graffiti removers - walnut shell granules have proven to be a number one choice.

Further Uses for Walnut Shell Flour:

• Filtration and separation of fluids
• Drilling, i.e. in drilling fluids and as pipe cleaning material
• Filling of coatings, especially where a lasting anti-slip effect is desired
• Filling of reinforced plastics used in extrusion or injection molding
• Industrial ceramics: as porosity enhancing and burn-out media
• Deflashing systems
• Agrochemicals: carriers for pesticides and herbicides
• Fertilizers: as base powder and binder

Walnut Shell Powder in Cosmetic Applications

As other nuts, walnuts can cause allergic reactions. The nut shell powder should therefore be used with care in applications related to skin contact or oral use. Although bio-based walnut shell granules have become a popular microplastic replacement in certain cosmetics, their ideal use should be on a more industrial scale. For fine personal care products such as body and face scrubs, we have optimized solutions (e.g. olive stone granules) with stronger benefits.
Walnut shell powder can be a filler medium for bio-based household solids, e.g. toiled rim blocks or soluble tablets of any type. Its binding and dispersing behavior can be combined with perfumes and colorants to create attractive biodegradable consumer items.

BioPowder is a reputable manufacturer and supplier of fruit stone granules, bio-based abrasives without any chemical additives. We attach great importance to sustainability and are proud of our outstanding product quality. We offer direct sale benefits and deliver to European countries (like UK, France, Germany, Switzerland, Austria etc.) and also worldwide. Contact us now!

FAQ – Walnut Shell Granules & Powder

Is walnut shell powder safe for skin?

Walnut shell powder is a natural material, but it isn’t hypoallergenic. It can cause skin or eye irritation and may contain trace amounts of walnut proteins that could trigger allergic reactions. Because it’s a mechanical exfoliant, dermatologists note that unrefined or uneven particles may disrupt the skin’s barrier—especially if you scrub aggressively. That said, there is no evidence that finely milled walnut shell powder is more harmful than other manual exfoliants when used gently. People with nut allergies or very sensitive skin should avoid contact, and those using walnut shell exfoliant should opt for fine, uniform particles and limit use to once or twice per week.

What is walnut shell powder used for?

Walnut shell powder (also marketed as wal nut shell granules, walnut shell abrasives or walnut shell flour) is a versatile industrial ingredient. Its Mohs hardness of around 3.5–4 makes it an effective natural abrasive for sandblasting, polishing and cleaning metal, carbon fibre, concrete and hard plastics. In aviation, coarse granules are used to clean turbine engines and remove coatings without damaging parts. The BioPowder site lists additional uses:

• Filtration and drilling: finely milled shells are used in filtration/separation of fluids and in drilling fluids to clean pipes.
• Additives & fillers: walnut shell flour is added to coatings, plastics and ceramics to improve porosity, anti-slip properties and to act as a burn-out medium.
• Carriers: granules serve as carriers for pesticides, herbicides and fertilizers.
• Household products: in compressed toilet rim blocks and other household solids, walnut shell powder helps bind and disperse ingredients. They are also a natural personal care ingredient.

Other sources mention that ground shells are used in personal-care products as a natural microplastic replacement (though alternatives like olive-stone granules may be preferred for sensitive skin).

What are the benefits of walnut shells?

Walnut shells are a by-product of the food industry and are biodegradable, renewable and non-toxic. Cosmetic-grade shells are free from major allergens, pesticide-free, non-GMO and contain no heavy metals. They absorb moisture and suspend well in formulations, making them useful as natural exfoliants. Walnut shells are composed of cellulose, hemicellulose and lignin; they are hard and porous, which makes them effective abrasives and allows them to adsorb liquids for water and air filtration. Beyond cosmetics, walnut shells improve soil structure and water retention when used as mulch or soil amendment, and they can be processed into biochar or biomass energy. These qualities make walnut shell granules an eco-friendly alternative to synthetic abrasives and fillers.

Is walnut shell good for rust removal?

Walnut shell abrasives can remove light rust, paint and grime without harming the underlying surface. Coarse grades effectively strip layers of carbon, soot and heavy dirt, while medium grades are used for restoring cars, removing graffiti and cleaning boats. Walnut shell blast media removes paint and rust from metal surfaces without damaging delicate substrates. However, because the media is relatively soft (Mohs 3.5–4), it is best suited for mild corrosion or surfaces that require a gentle touch; heavily rusted steel may require harder abrasives like garnet or aluminum oxide.

Are walnut shells good for exfoliation?

Walnut shell exfoliant is widely used as a natural substitute for plastic microbeads. Finely milled shells can unclog pores and remove dead skin cells and excess oils. Nevertheless, dermatologists caution that coarse or irregular particles may scratch the skin. Still, walnut shell exfoliant is many cases a good alternative to plastic microbeads. Sensitive individuals should use finely ground, uniform particles and gentle pressure, and those with nut allergies should avoid the ingredient altogether. Alternatives like olive-stone or apricot-stone granules offer similar exfoliation with a smoother texture.

What grit are walnut shells?

Walnut shell abrasives and flours are sold in standardized mesh sizes. Common grades range from very coarse 6–10 mesh up to fine 60–200 mesh. Grit size affects performance: 6/10 mesh is the roughest and is used to remove carbon and heavy dirt; 12/20 mesh offers a balance of power and control for graffiti removal and car restoration; 20/30 mesh is gentle enough for wooden furniture and delicate metals; and 30/100 mesh is extremely fine, suitable for cosmetic finishing or cleaning sensitive plastics.