Bone Ash

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Usually ships the next business day.

Bone ash is made from selected bones properly leached, ground, chemically treated, calcined by a special procedure and milled to a small particle size. Our bone ash is obtained by roasting degelatinized bone up to a temperature of approximately 1100° C. Afterwards, the bone ash is cooled and ground to a fine particle size so that a minimum of 95% will pass through a 325-mesh (U.S. Standard) sieve or through a 20-mesh sieve for 20 mesh bone ash. The excellent properties of bone ash is attributed to the internal structure of the small, individual particles. The original cellular structure of the bone is preserved, thus giving the material a high resistance to heat transfer (natural thermal insulator). Bone ash is primarily tri-calcium phosphate or a form of calcium hydroxyapatite.

Bone ash has the following intrinsic properties:

• Has excellent non-wetting properties
• Is chemically inert and free of organic matter
• Has high resistance to heat transfer (natural thermal insulator)

In painting grounds, it makes a durable surface while adding some tooth especially for egg and casein tempera, distemper, encaustic and oil painting. Use in chalk and gesso grounds to increase absorbency and add texture. Bone ash is used in Cennino’s recipe for silverpoint grounds.

Add to oil colors and mediums to create textural and bodying qualities to oil paint without affecting the color. Bone ash has little color in drying oil, so it can be added to oil paint without affecting the color temperature.

Bone Ash (20 Mesh) Bone Ash (325 Mesh)
Ash from calcined and degelatinized bone Ash from calcined and degelatinized bone
Typical Chemical Analysis
Tri-Calcium Phosphate (Ca3 [PO4]O2) 95.00% 96.90%
Calcium Oxide (CaO) 54.50% 55.25%
Phosphorus Pentoxide (P2O5) 41.50% 41.65%
Magnesium Oxide (MgO)
Shipping from
This product is shipped from our supplier's warehouse in Willits, CA, United States
Our guarantee
This product is brand new and includes the manufacturer's warranty, so you can buy with confidence.
A 25% handling charge is levied against all authorized returns except those due to our error. Unauthorized returns are subject to a 40% handling charge. Damages & defects must be reported to us within 14 days.
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