Free sulfur: quantity and effect

The standard

The effective molecular fraction measures protection not by the free total but by the part that, at the given pH value, is present in molecular form. The same free value protects less at a higher pH value.

Criteria

• The free share is measured apart from the bound one
• The pH value is carried along as a condition of the effect
• Protection is measured by the molecular form, not by the total
• The addition follows the measurement, not a fixed figure

Distinction

Free sulfur ≠ Bound forms of SO₂: one is the unbound share, the other the bound one. Free sulfur ≠ total sulfur: only the free part protects, and of it only the molecular form. The effective molecular fraction thus separates quantity from effect.