Garden Lime vs. Pickling Lime for Indigo Dyeing

They are chemically different. Garden lime is calcium carbonate (CaCO₃), while pickling lime is calcium hydroxide (Ca(OH)₂). Calcium hydroxide is far more alkaline, providing the high pH needed to dissolve raw indigo and create a functional dye vat. Garden lime cannot substitute because it doesn't raise pH enough. Other strong alkalis like sodium hydroxide (lye) can work but are highly caustic—use with extreme caution. For safe, effective indigo vats, source food-grade pickling lime (calcium hydroxide) from canning supply retailers.