Look at the two papers in http://microlab.berkeley.edu/labmanual/chap1/JMEMSEtchRates1(1996).pdf http://microlab.berkeley.edu/labmanual/chap1/JMEMSEtchRates2(2003).pdf These cover mixing BHF and many other etchants and give etch rates for fused quartz, Pyrex 7740 glass, several deposited oxides, and many other materials. Note that BHF will faster and less controllably immediately after mixing. It's best to buy it premixed, or mix it and let it sit for a day before using. --Kirt Williams ----- Original Message ----- From: "Barbara Cortese"To: "mems-talk" Sent: Friday, January 19, 2007 12:56 AM Subject: [mems-talk] BHF solution Hi to all I'm etching glass and quartz by a wet etching solution of BHF, but my recipe isn't too good. I've tried differrent solutions with no success. Has anyone a good recipe to suggest me?(not just saying BHF 6:1! but the effective quantities!).