HF GEL is a porcelain etchant containing 9.6% buffered hydrofluoric acid in gel form that must be handled with extreme care (see warnings). HF GEL has been buffered, gelled and packaged to minimize problems, provided that it is used in accordance with these instructions. Porcelain etchant improves the mechanical bond between porcelain and adhesive/cement by increasing the surface area of the porcelain. The effect is similar to sandblasting but is more controlled and effective