[brewdude]

Hi Everyone,

This is my first post here,, I hope I am making it in the correct forum.

I am using a solution of Ammonium Bi-fluoride (saturated in DI water at 85 deg C, about 2.7 grams of the salt in 150 ml of water) to try to etch and polish a piece of fused silica. And I am getting some very strange results. The finish of the glass is very 'splotchy' and nonuniform. It seems to get a little better the more I use the same mixture (IE the third, or fourth piece is almost totally smooth).

Has anyone out there wrestled with this before? Is there some sort of 'seasoning' of the reaction taking place? . I know the glass is very clean going into my little process and I have even taken steps to warm the glass before etching (in 90 deg DIW). Any help would be greatly appreciated!