Mixing the Glue
The 'type' or 'pattern' of desired chip design is dependent upon the glue to water ratio.
Generally the dry glue is combined with COLD water in a ratio of 3 parts water, 1 part glue. This is measured by WEIGHT - 1 oz. of glue to 3 oz. of COLD water per sq. ft. of glass. If your glass is 24"x24", this is 4 sq. ft. so you will need 4 oz. of DRY glue and 12 oz. of cold water.
Using metric measurements is easier when combining wet and dry materials by weight. 1 litre of water is 1 kg. So for 0.1 sq. metre (approximately 1 sq. foot) of glass you need 25 grams of glue to 75 cl of water.
After mixing let this mixture stand for about 1 hour to absorb all the liquid. It also helps to cover this container to reduce evaporation. This mixture will form a gelatinous mass.
Average Recipe:1 to 2 ounces of Dry Glue per sq. ft.
3 ounces of COLD water per sq. ft.
285 to 570 grams of dry glue per square metre
850 centilitres of Cold water per square metre
Heat this mixture in the double boiler. Do not try to heat the glue container directly on a burner. This will stink tremendously. Slowly heat this mixture to 60 – 65C (140 - 150 F). It is important that you do not boil this mixture and that is stays between these temperatures. Use a sugar/candy thermometer to measure the temperature of glue. Stir occasionally. Heat slowly.