The components commonly used in "dry process" solvents are mainly of the following types:
(1) Using hydrochloric acid (HCl) with a concentration of 31% (360 grams per liter, with a Baumé degree above 19) directly as the solvent;
(2) Using an aqueous solution of zinc chloride (ZnCl₂) as the solvent;
(3) Using an aqueous solution of ammonium chloride (NH₄Cl) as the solvent;
(4) Using an aqueous solution of a complex salt of ammonium chloride and zinc chloride as the solvent.
In China's hot-dip galvanized steel pipe factories, the solvent used is mostly an aqueous solution of the complex salt of ammonium chloride and zinc chloride.
