Ferrous sulfate

Used as a mordant and dye modifier, shifting many dyes darker. Sold by Alpha Chemicals on Amazon: https://www.amazon.com/dp/B007ODUI76?ref=nb_sb_ss_w_as-reorder_k1_1_7&amp=&crid=1BJL9Y8KL4ZM3&amp=&sprefix=ferrous.

First purchased June 1, 2025.