Treatment dosage scales with surface area. How do I set it for a new grade?

There is no universal figure. Dosage is set per powder, from its specific surface area and from what you want the treatment to do.

The rule is straightforward: the higher the specific surface area, the more agent is needed to reach the same coverage. Fine and porous grades — high-absorption silica, nano TiO2 — therefore carry noticeably more agent than coarse, low-area fillers at the same weight percentage.

Coverage can be estimated as agent loading divided by (specific surface area × area per molecule), but treat that as an order-of-magnitude check, not a specification. It assumes a uniform monolayer, and a real treatment self-aggregates and covers unevenly.

What actually sets the number is performance: oil absorption should fall, dispersion in the target oil phase should improve, water repellence should shift, and stability should hold. Ask the supplier for the agent loading and for the process — dry or wet — because two grades both labelled "SI treated" can behave differently.