Can I claim silicone-free when the powder is SI-treated?

No — not if the treatment is a silicone. This is the most common place a "silicone-free" claim fails.

"SI" is a family label, not an ingredient. The agent may be dimethicone, a polymethylsiloxane or a combination. AS is triethoxycaprylylsilane, DSG is disodium stearoyl glutamate, ITT is isopropyl titanium triisostearate. Each has a different regulatory standing, and some carry concentration or use limits.

Ask for three things with every treated grade: the full INCI names with content ranges, the permitted-use basis in the target market, and a COA for the treated powder as a whole.

Two places this bites. The agent content counts toward the formula total, so a limited ingredient can be pushed over its cap by the powder rather than by a direct addition. And combination treatments — ITT over SI, for instance — multiply the number of ingredients to clear one by one. A claim like silicone-free, oil-free or PEG-free has to be checked against the treatment, never assumed to sit outside it.