Gingi-pak EtchPro Gel- Etching Gel 1.2ml Syringe 38% Phosphoric AcidGingi pak EtchPro Gel Etching Gel 1. 2ml Syringe 38% Phosphoric Acid. FDA approved. Rinses cleanly without residue. Uniquely formulated gel mixes evenly and never separates. Superior viscosity with self leveling to allow maximal penetration. Overview Its self limiting etch formula creates an ideal etch pattern with an average depth of 1. 9 m from a 15 second etch, allowing for maximum adhesive penetration for increased bond strength. Precise placement