appears that the degree of etching or removal of material from the article to achieve optimum results will depend upon the nature of the sample being treated generally the removal of a depth of from about 4 to about 20 mils gives substantial improvement in the tensile strength it has also been noted that the effects of exposure of the treated articles to the ambient atmosphere will cause the tensile strength to decrease with time accordingly the treated articles should be protected from the effects of carbon dioxide and water vapor if they are to be stored for any length of time prior to use in the alternative they should be used within a few hours of treatment following the acid treatment which is conveniently carried out by immersing the articles in the acid bath the articles are rinsed with ammonium hydroxide and isopropyl alcohol or with deionized water isopropyl alcohol and freon fluorinated hydrocarbon other conventional liquid solid contacting techniques such as by spraying can also be used to treat the articles in order to further illustrate the process of the invention various lead lead and baria and baria glasses were treated and subjected to flexure testing as illustrated in the following examples samples of saw cut high lead glass having a 150 mil on the side square cross section and a length of about 3 0 inches were treated for varying.