Today, SRS Stonecast is the industry leader for wax setting investment powders. It works by ensuring that the correct de-oxidising additives are present, thereby minimising the risk of damage to diamonds or other precious stones. These include problems with burnt diamonds, accelerated set times, incomplete filling, spalling and flashing over or under stones.
Powder / Water Ratio : 100/38-40
Working Time @ 22c Slurry Temp. :8 min.
Gloss Off Time @ 22c Slurry Temp. : 10-12 min.
Thermal Expansion At 750c : 1.15%
Powder can be both dry and steam dewaxed with excellent result. As a general rule the larger the flask the longer the dewax time. Dry dewax in a furnace should take place at about 230c. For a 6″x4″ jewellery mold, 3 hours will be sufficient to remove the bulk of the wax and 2 hours should be sufficient for steam dewax.
Burnout cycles will depend very much on the size of the flask. The larger the flask or the waxes therein the longer and more gradual the burnout must be. For 6”x4” mould will only need 12 hours. In addition the furnace must have a good supply of air in order to achieve a clean burnout. Carbon deposits from the wax must combine with oxygen to form CO2 and thus excape through the pores of the investment. If after Burnout your mould is a gray colour you need to get more air into the furnace-do not increase the temperature, this will only damage the investment.
After completion of burnout, the flask should be cooled to proper casting temperature. The flask can then be cast by either centrifugal or vacuum casting methods.
Temperature of the last 1-2 hours of burnout must be adjusted at correct temperature for casting. If held for less than 1 hour, the core of the flasks will be at a much higher temperature, and may result in metal mold reaction.
The casting temperature varies considerable depending on the size of wax piece and type of metal to be cast. Please contact us for our recommendations.