Assay, physical form and compliance decide whether a grade cures your resin, whitens your flour, or wastes a batch. Here's how to pick correctly the first time.
Benzoyl peroxide is not a single product. The white powder that whitens bakery flour and the one that initiates PVC polymerisation are the same molecule at very different strengths, and using the wrong one means a failed cure, an off spec food product, or an unnecessary safety risk. Dhiraj Chemicals manufactures seven benzoyl peroxide grades, and this guide explains how to match them to the job.
What the percentage actually means
The number on the grade (20%, 32%, 50%, 75%) is the assay, the share of active benzoyl peroxide in the powder. The remainder is a phlegmatiser (water or an inert carrier) that keeps the material stable and safe to handle. As an organic peroxide, pure BPO is reactive; diluting it to a known, consistent assay is what makes it usable in a factory.
The practical rule: higher assay means higher reactivity and more active initiator per kilo, but also more careful handling. A polymer plant wants the concentrated 75% grade; a flour mill wants a food safe grade in the 32% to 34% range dosed at parts per million. Choosing on assay alone is the first filter; form and compliance narrow it the rest of the way.
Match the grade to the job
Every grade Dhiraj makes is built around a real application. Start from what you are producing:
| Grade | Best for | Why this one |
|---|---|---|
| BPO 20% | Construction resins, grouting, general bleaching | Gentle assay for ambient temperature resin curing |
| BPO 32% / 34% | Flour whitening & treatment (food) | Food grade, FSSAI backed, dosed in ppm |
| BPO 50% powder | MMA cold plastic road marking | Right reactivity as a two component hardener |
| BPO 50% paste | Unsaturated polyester, body fillers | Paste form doses safely into liquid resins |
| BPO 75% | PVC / polyester polymerisation, rubber, EPS | High active content for industrial initiation |
| Ultra fine | Pharma, dermatological, cosmetic, specialty polymers | Fine particle size for superior dispersion |
Powder, paste or ultra fine: form matters as much as strength
Two grades at the same assay can behave very differently because of physical form:
- › Free flowing powder: easy to weigh and blend; the default for most industrial and food dosing.
- › Thixotropic paste: the peroxide is pre dispersed, so it mixes cleanly into liquid polyester resins with less dust and safer handling.
- › Ultra fine powder: a smaller particle size that disperses more evenly, which matters where consistency governs performance: dermatological and cosmetic formulations, and high precision polymer work.
Don't overlook compliance
For food and pharmaceutical work, the grade's paperwork is part of the specification. A food application needs a grade backed by FSSAI and HACCP; regulated pharmaceutical and dermatological work needs GMP aligned manufacturing and batch to batch consistency. Using an industrial strength grade in these settings isn't just wrong technically, it's non compliant. Dhiraj's food and specialty grades are made under ISO 9001:2015, GMP, FSSAI, HACCP and Halal certification for exactly this reason.
Tell us the application (the resin, the monomer, the flour, the cure temperature) and our technical team will recommend the right grade and dosing. We also supply customised grades tailored to particle size and concentration. Request a recommendation →