Media and methods for etching glass
Described herein are aqueous acidic glass etching solutions or media comprising HF and H 2 SO 4 , wherein HF is present in concentrations not exceeding about 1.3M. The etching solutions are used to treat glass articles such as thin glass sheets at above-ambient temperatures to etch slight thicknesses of surface glass therefrom, the etching solutions exhibiting improved stability against dissolved glass precipitation and rapid glass removal rates at slightly elevated temperatures.
1. An acid bath for glass etching, the bath comprising an acid mixture consisting essentially of HF, H 2 SO 4 , water, dissolved glass constituents, and a KSiF 6 precipitate, wherein the concentration of HF does not exceed about 1.3M and H 2 SO 4 is present at a concentration of about 0.5M to about 1.5M.
2. The solution of claim 1 , wherein H 2 SO 4 is present at a concentration of about 0.5M to about 0.9M.
3. A method for treating a glass article, the method comprising contacting the glass article with an aqueous acidic etching solution comprising an acid mixture consisting essentially of HF, H 2 SO 4 , water, dissolved glass constituents, and a KSiF 6 precipitate, wherein the concentration of HF does not exceed about 1.3M and H 2 SO 4 S present at a concentration of about 0.5M to about 1.5.
4. The method of claim 3 , wherein the contacting is conducted at a temperature of at least about 30 ° C.
5. The method of claim 3 , wherein the contacting comprises spraying the glass article with the aqueous acidic etching solution at a solution temperature of about 30 to about 45 ° C.
6. The method of claim 3 , wherein the contacting is conducted for a time sufficient to remove a glass surface layer having a thickness of about 1 to about 4 micrometers from the glass article.
7. The method of claim 3 , wherein the glass article comprises an alkali aluminosilicate glass comprising potassium oxide.
8. The method of claim 3 , wherein the glass article is a glass sheet having a thickness not exceeding about 2 millimeters.
9. The method of claim 3 , wherein the glass article comprises a potassium oxide-containing surface compression layer.
10. The method of claim 3 , wherein the glass article comprises a surface compression layer having an exposed surface comprising potassium oxide in a concentration greater than about 10 weight percent.
11. The method of claim 3 , wherein the aqueous acidic etching solution comprises dissolved glass constituents at a concentration of about 1 to about 12 grams per liter.