Buyers often ask for "activated charcoal powder" without further qualification. The term covers materials whose performance varies by a factor of three or more, and the four numbers below explain most of that variance.

Iodine number

Measured in mg/g, iodine number is a proxy for total surface area and for the volume of small pores. Higher means more adsorptive capacity for small molecules. Food-grade coconut shell carbon typically runs 900–1100 mg/g; premium filtration grades reach 1200 mg/g and above. For supplement use, anything above 900 is generally sufficient, and paying for 1200 buys capacity you will not use.

Mesh size

Mesh governs contact area and flow behaviour. Powdered carbon at 200–325 mesh adsorbs fastest and suits capsules, tablets and batch decolourising. Granular carbon at 8×30 or 12×40 mesh suits packed columns and flowing water, where a powder would simply blind the bed. Choosing the wrong form is the single most common specification error we see.

Ash content

Ash is the inorganic residue left after combustion. Lower ash means fewer leachable minerals and less interference in sensitive processes. Coconut shell carbon is naturally low, at 3–5%; hardwood runs higher. For pharmaceutical purification, acid-washed grades bring ash below 1% and strip residual iron.

Wash grade

Standard carbon carries residual mineral content from its feedstock. Acid-washed carbon has been treated to remove those extractables, which matters when the carbon contacts an API or an injectable process stream. USP-grade material meets the monograph and is the correct choice where a pharmacopoeial specification is required.

Matching grade to application

  • Capsules and tablets — coconut shell powder, 200–325 mesh, iodine 900+, food grade
  • Cosmetic masks and toothpaste — fine powder, 325 mesh, low grit, bamboo or coconut
  • Water and beverage filtration — granular coconut shell, 8×30 or 12×40 mesh
  • Sugar and glycerine decolourising — powdered hardwood, high molasses number
  • Pharmaceutical purification — acid-washed or USP-grade powder, ash below 1%

A note on feedstock

Coconut shell yields a hard, microporous carbon that resists attrition and suits both ingestion and column work. Hardwood produces a more mesoporous carbon that excels at removing large colour bodies. Bamboo sits between the two and is favoured in cosmetics for its fine, uniform particle. Feedstock is a genuine performance variable, not a marketing detail.

Send us the application and the contaminant you are targeting and we will recommend a grade — including telling you when a cheaper one will do the job.