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Before you start casting final works, it's a good idea to make at least one cast to clean the mould of plaster and release agent. Although the moulds are thoroughly washed after manufacture, traces of these materials may remain on them. In order to clean the mould, it is sufficient to make a thin cast and then throw it away so as not to risk transferring plaster residue to the casted part.
You can dry the moulds at temperatures of up to 50°C. Exceeding this temperature may damage the moulds or cause them to wear out more quickly. Never dry the moulds on the kiln while firing!
Models made with 3D printing technology (PLA, resin) should be kept away from heat sources. These models may survive intact for several decades provided that they are tightly packed. You should also protect them from accidental mechanical damage.
Remember: the key to superior results in slip casting is first and foremost a well-prepared casting slip. Even the best plaster mould won't do its job if the casting slip doesn't have the right properties, i.e. specific weight, viscosity and thixotropy. Some casting slips will perform well in simple one-piece mould casts, but may fail when trying to cast a plate in a full casting mould. Without the ability to recognize which properties of the casting slip need to be improved, it will be hard to control the whole process, and any success may prove random and short-lived. Adding large amounts of liquefier to the casting slip may significantly shorten the life of the mould – use only as much as necessary. In the case of simple shapes with smooth surface, I have managed to make as many as 80-100 casts from a single mould. With intricate textures, the mould may wear out more quickly, because casting slip successively washes the plaster away and thus rounds off sharp textures and details.
If you have several moulds of the same type, label them, e.g. with numbers, to monitor the problems that may arise while using them.
In the case of casting in more difficult moulds, e.g.:
- large and heavy;
- large in volume with a small inlet;
- possessing difficult textures or shapes causing the cast to be sucked in or stuck;
- moulds for full casting with very small inlets
various recipes can be used to facilitate pouring the slip, emptying and extracting the cast. It is often necessary to make several failed casts in order to work out the technology, particularly to determine the casting time, the wait before de-moulding etc. In cases like these, I put forward solutions that I heard of or personally tested.
Any questions or doubts about how to handle models and moulds that I manufactured? Please contact me..