Blue Etchant Gel 37% Phosphoric Acid. Includes 1 - 12 Gm. Syringe and Tips. Contains: (1) 12 gm. Syringe, (3) Dispensing Tips. Prime-Dent Etchant Gel 37% phosphoric acid is a medium viscosity etchant gel used for etching enamel and dentin prior to bonding procedures. Prime-Dent Etchant Gel is thixotropic, stays where placed and will not run. Does not dry out and has a long shelf life when properly stored.