Hydrochloric Acid

Hydrochloric acid (aqueous hydrogen chloride) shows up in trace amounts in some glass-coating formulas as a catalyst — it lowers the pH enough to activate the silanol-to-siloxane bonding reaction that cures the coating to the glass surface. At the typical concentrations used (well under 1% in the finished product), the corrosive and irritant classifications that apply to concentrated HCl do not transfer to the mixture: the specific concentration limits under CLP are 25% for skin corrosion (H314), 10% for eye irritation (H319), and 10% for respiratory irritation (H335). Below those thresholds the contribution is functional chemistry, not a classified hazard.

In a finished glass-coating bottle the HCl trace is consumed during the cure reaction — there is no meaningful residual acid on the cured film. Read the full SDS Section 3 concentration band before assuming a glass coating is corrosive based on the ingredient list alone; trace HCl in a 91-96% IPA carrier is normal alkoxysilane chemistry, not a Skin Corr. 1B product.