They are all easy to control and apply, and Keystone offers two gels for different surfaces: Ceramic and Metal.

• Ceramic Etch Gel: will chemically etch entire surface where gel comes into contact with ceramic material. This will create a roughened undercut surface.
• Metal Etch Gel: will selectively remove base materials from the alloy to create a roughened undercut surface. This has a nickel base, containing 10% hydrochloric acid, 4% nitric acid and 1% hydrofluoric acid. The higher gold content, the better it works. NOTE: Does not work well with silver, copper, and gallium.