Borax

white-powder

Composition (INCI) Hydrated sodium borate or sodium tetraborate
Form crystals
Origin mineral (evaporite)
Elaboration process stone crushing, fractionated distillation, solvent extraction (sodium carbonate or hydroxide) and evaporation
Functions Biocide, preservative, detergent, whitening, water softening
Dosage 20-30% powder, 2-3% liquid
Solubility soluble in acids
Standard conservation
Usage precautions Direct contact with eyes may cause severe irritation with redness, pain, blurred vision, and possibly corneal injury. Repeated or prolonged excessive exposure with skin can result in irritation.

Source: Borax safety datasheet