Does treatment raise tinting strength? Do I have to cut the loading?

Yes, usually — and yes, expect to cut the loading when you move from an untreated to a treated pigment.

The gain is a dispersion effect, not a stronger pigment. Fewer agglomerates mean more effective colouring area, so the same weight reads more saturated and deeper.

Opacity can move the other way. The layer narrows the refractive index difference between pigment and base, so scattering drops slightly, and a thick layer shows it more. In most cases the improved uniformity from better dispersion offsets the loss.

In practice a straight swap at equal loading comes out too deep. Cut by roughly 5–15% depending on how light the shade is, then bring it back to target.

Verify with equal-loading drawdowns, reading L/a/b and contrast ratio, then adjust. Deep shades tolerate the shift; pale and bright ones — pinks, oranges — need re-matching every time.