Boric acid

Boric acid (CAS 10043-35-3), also known as boracic acid and approved as food preservative E284, is an inorganic boron compound sourced for its buffering and biocidal functions.

Where is Boric acid used?

• Glass fiber and fiberglass: lowers melt viscosity and improves tensile strength in the final reinforcement product
• Textile and leather: flame retardant finish and mold inhibitor
• Wood treatment and building products: protects timber against fungi, insects, and fire, often in combination with other boron salts
• Personal care and pharmaceutical: pH buffer and mild preservative in topical formulations and ophthalmic solutions
• It acts as a pH buffer, preservative, and fire-suppressing agent depending on the application and concentration.

Good to know: Granular forms are preferred for dust-sensitive handling. Food-grade material is available to E284 specification for permitted preservation uses.

Regulatory status

• Listed in Annex XVII entry 30 appendix 6 of REACH, so it cannot be placed on the market or used by the general public at concentrations of 0.3% or more, and packaging must be labelled 'Reserved for professional users'.
• Among the boron compounds prohibited in cosmetic products under Regulation (EC) No 1223/2009.
• Specific concentration limits were removed by Commission Delegated Regulation (EU) 2021/849, so the generic concentration limit of 0.3% for Repr. 1B substances applies from 17 December 2022.

Frequently asked questions about Boric acid

What is the harmonised CLP classification and hazard statement for boric acid in the EU?

Boric acid has a harmonised classification as Repr. 1B with the hazard statement H360FD: May damage fertility. May damage the unborn child.

Does the supplier need to self-classify boric acid in addition to the harmonised classification?

The harmonised CLP labelling for boric acid is mandatory and must be supplemented by the supplier's own self-classification where applicable.

Are there any exemptions to the REACH restriction for boric acid?

The REACH restriction for boric acid does not apply to cosmetic products, medicinal and veterinary products, fuels and 'artistic' paints.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.