Similar to sand casting this process is carried out using plaster of Paris, and can only be used with non ferrous metals. However, unlike other forms of casting this cannot be done at home by inexperienced people. It is no good wanting to start a hobby with your children and choosing this one. Even though it may not seem so far from other forms of modelling, there are so many differences and pitfalls. Casting plaster molds should be carefully researched before you start, and it may well be that when you have done that you decide that you would rather either start or stick to another method.
You will need much more equipment and it is not suitable for children to around such heat. It is a job for a professional and a career that can take some time to master. Although it can still be fun, there can be no distractions and losing concentration for just a minute can at best ruin the article, and at worst cause an injury. Although there are so many limitations on this form with practice the method can be mastered, and much more beautiful products can be provided.
Casting plaster molds are used when an excellent surface finish and good dimensional accuracy is required and when you want a good quality product, and are prepared to be patient and careful enough to get it. There are a number of advantages and disadvantages to this system. The metal will cool much more slowly than the process using sand. An incredibly important factor in this is that it is much cheaper than other methods. Using this method, you will find that there is very little waste.
You will also find that you are able to model items that are more intricate and get a much better copy of the original. There is the choice to have a much finer finish rather than chunky copies of other methods. The finish will be very good and to a standard not possible with other types of casting. The disadvantage is that you cannot use this system for all metal. You have to use metals such as aluminium and copper, as it is not possible to heat to a level above 1200F.
A further disadvantage is the amount of time that the item takes to cool. If time is not an issue that may not be a problem. However, it is not a process to use, if you want mass production. This will not be a system to use unless you are incredibly experienced. Little things can ruin the whole process, such as not mixing the plaster of Paris to exactly the right consistency or not pouring it in properly. The best you can hope for in cases like this is the item shrinking, but normally it just will not work at all. It cannot be left and needs to be monitored carefully all the way through. The one point to be emphasised is be careful casting plaster molds.