There are a lot of basic things that beginners need to know about working with mold making and casting materials like alginate, clay, plaster, polyurethane resin, silicone rubber, liquid latex rubber and thermoset mold rubber.
Pot time (or Pot Life) and cure time are routinely mentioned by mold makers and this determines everything from the quantity of a mold making or casting material that mold maker will mix in one go, to the amount of time it will take for the mold or cast to be complete and ready.
Let’s look at some of these terms:
Pot time – Also known as pot life, gel time or working time, this is the amount of time you have to work with the product after it is mixed until it starts to set. After this, the material will start getting viscous and cannot be applied properly. The working time varies widely for different materials – some may need to be used within minutes, whereas some may give you a window of even up to an hour. Therefore, you should only mix as much quantity of the base material with the catalyst or hardener as you can comfortably use within the given period. For instance, life casters mix small quantities of alginate,perhaps a pound at a time as it tends to set very quickly.
Cure time – This is the time that a material will take to completely set. It can range from a few hours to as long as a few days. It is generally measured at normal room temperature and can vary depending on the atmospheric and climatic conditions. At times, a hot air dryer or dehumidifier is used to hasten the cure time, like for plaster casting.
De-mold time – At times, the de-mold time may be different from the cure time. It means that the mold or cast has cured to the point that it can be removed from the object or mold without distortion. You are now free to use the object or mold again. However, keep in mind that the mold or cast is only partially cured at this time. The cure time is longer and you will have to wait for it to be properly cured to avoid getting smudges or fingerprints.
Shelf life – This defines the length of time that a product can be stored before it becomes unusable. It is like an expiry date beyond which the product starts deteriorating in quality and will not function as expected. It may start to set in the container or may not mix/cure properly when used. In simple terms, shelf life is an indication of how long you can expect a product to last on the shelf. It tends to vary depending on whether the container has been opened or not and also whether it is being stored properly as directed.
Pot time, cure time and shelf life are generally mentioned on the product containers and should be strictly adhered to at all times, irrespective of whether you are making alginate molds, silicone casts or plaster casting.
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