Zinc pyrithione

Zinc pyrithione (CAS 13463-41-7), commonly abbreviated as ZPT, is a broad-spectrum antimicrobial agent. Also known as zinc pyridinethione.

Where is Zinc pyrithione used?

• Antidandruff shampoos and scalp treatments: active ingredient controlling Malassezia yeast
• Marine and architectural coatings: biocidal additive preventing algae, mold and mildew on exterior surfaces
• Adhesives, sealants and elastomers: extend shelf life and resist microbial degradation in humid or outdoor environments
• Industrial water treatment systems suppress microbial fouling in recirculating and process water circuits.
• Textile finishes.

Good to know: Cosmetic-grade material is subject to purity requirements aligned with regional regulatory limits for leave-on and rinse-off formulations.

Formulation notes

• Chemically incompatible with paints that rely on metal carboxylate curing agents.
• In latex paints with water containing high amounts of iron, a sequestering agent that preferentially binds iron ions is needed.
• Can be destabilized by chelating agents and certain transition metal ions, notably copper and iron salts, causing discoloration or loss of activity.

Typical specification

• Offered as a 48% aqueous suspension.
• Cosmetic-grade purity is at least 98%.
• The 48% aqueous suspension is a white slightly viscous liquid.

Regulatory status

• Added to Annex II (list of prohibited substances) of Regulation (EC) No 1223/2009 under entry number 1670.
• Classified UN 2811 and shipped as regulated dangerous goods with appropriate packaging and documentation.
• Listed in Turkey cosmetics regulations Annex II as a prohibited substance.

Storage, packaging and handling

• Do not store above 30°C.

Frequently asked questions about Zinc pyrithione

What is the biocidal regulatory status of zinc pyrithione in the EU?

It is under evaluation for product types 02, 06, 07, 09, 10 and 21 under the Biocidal Products Regulation.

What harmonised classification applies to zinc pyrithione?

From 1 March 2022, the harmonised classification under the 15th ATP includes Repr. 1B, H360D.

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