height of linkage bumps and the amount of glass removed during the pre etch chemical polishing step the glass substrates used for these experiments were polished with coarse ceo 2 powder mean particle diameter of 2 microns without the above described gentle mechanical polishing process for the substrate without pre etch chemical polishing after chemical texturing linkage bumps of 100 u00e5 to 800 u00e5 height and an average height of 390 u00e5 were found on the substrate surface see the comparison test in table 1 below referring again to fig8 another substrate was subjected to a pre etch chemical polishing step after mechanical polishing with coarse ceo 2 during which the substrate was etched to a depth of 80 u00e5 by soaking the substrate in a solution comprising 0 05 wt hf and 0 05 wt h 2 so 4 for 6 minutes at 35 u00b0 c after chemical texturing no linkage bumps exceeding a height of 400 u00e5 were found and the average height of the linkage bumps was about 200 u00e5 for the substrate which was subjected to a pre etch chemical polishing step during which 280 u00e5 of glass was removed no linkage bumps higher than 200 u00e5 were found after texturing this substrate shown in fig7 was used to generate the test data for test 1 in table i below table i contains data concerning the heights of linkage bumps formed on glass substrates after chemical texturing the tests in table i were performed by.