Sodium Thioglycolate

Sodium thioglycolate is the sodium salt of thioglycolic acid — the same iron-reactive chemistry as ammonium thioglycolate but using sodium as the counterion. It reacts with iron oxide (brake dust) to form a purple iron-thioglycolate complex, providing visible feedback that decontamination is occurring. Used in Griot's Garage Iron & Fallout Remover at 25% concentration. At the product level, Griot's SDS classifies the mixture as WARNING with H302/H315/H319 only — notably milder than products using ammonium thioglycolate at similar concentrations, which typically carry DANGER with H318 (serious eye damage) and H312 (harmful in contact with skin). Whether this reflects the salt form, concentration effects, or formulation choices is not clear from the SDS alone. Aerobically biodegradable in wastewater treatment. The purple iron-thioglycolate runoff from wheel cleaning should go to sanitary sewer, not storm drain, as a general best practice for iron-remover rinse water.