Tek Gel for Profiling – Medium Grade gelled acid TGP is used for etching concrete When a 120 sand paper grit opening or profile is required. This is the profile most manufacturers of coatings, sealers and paints require in order for them to stand behind the warranty of their products. When the secondary colorant is NOT acid stain. We have many contractors use TGP and still get fantastic acid stain to uniformly burn in, however, unless you’re a seasoned applicator, you may be playing with fire. TGP is designed to be aggressive on top laitance.