Macs Mud White Casting Slip is a high-quality casting clay made from a well-balanced formula for plasticity, minimum shrinkage, reliable greenware strength, and easy casting ability. This white firing casting slip is made from high quality raw materials. Developed to be compatible with our own stocked clear glazes as well as many other commercially available glazes, they are regularly tested for fit and performance. 

Note that Macs Mud White Casting Slip replaces Windsor White Casting Slip, which is no longer in production. 


10 to 30 minutes depending on the size and shape of the items. On average a 5mm wall thickness is recommended, but this can be increased to 8mm for larger items.


10 to 20 minutes. The moulds should rest at a steep angle to ensure good drainage. 


Recommended to be done at the end of the draining time while the cast is still against the mould. If left for too long the cast will shrink away from the mould (as it is designed to do), making trimming difficult. A very sharp knife must be used, taking care not to damage the moulds. 


Remove when the cast has 'set' and is considered firm enough not to deform during removal. This is usually at least an hour after trimming. Removal too early can deform the item, and this can be exacerbated during firing. 


Best late in the leather hard stage, or when dry. Use fettling knives, Scotch Brite pads and/or sponges. Ensure edges and rims are nicely rounded. 


Firing range is 1180 to 1280 degrees. Optimum temperature is 1800 to 1240 degrees. Items can be fired up to 200 degrees Celsius per hour, with a similar cooling rate. Water absorption at 1180 degrees is approximately 9%. Shrinkage at 1180 degrees is approximately 10%. 


Reintroduction of trimming scraps into the casting slip is not recommended as this will upset the deflocculant balance, and consequently casting ability. 


Thixotropy (the property of becoming less viscous when subjected to agitation) of the slip controls the casting rate. Thixotropy can also be affected by the ambient temperature of the slip, and slips also tend to thicken over long periods. To increase fluidity, very small amounts of sodium dispex can be added. Start with no more than 1 - 2 mls of dispex per 10 litre bucket of slip, and mix thoroughly. We do not recommend the addition of water to make slips more fluid. This can easily upset the deflocculant balance. Slip can be made more viscous with very small amounts of Epsom Salt or Calcium Chloride solution. Add in very small increments (1 - 2mls) and mix thoroughly between additions. 


Moulds need to be clean and dry for the casting system to work effectively.


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