One of the all time favourites because of its ease of use and predictable results. Green sand will also retain moisture for weeks on end in a plastic garbage bin.
Green sand is the most efficient, low cost way for the hobby worker to start making moulds for metal casting. But the trouble with green sand is the need for a Muller to make your first batch. Green sand does require maintenance and looking after to get the best results, but it will last for many years for hobby use, and can be used over and over again.
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Co2 Gas System & Dry Sand.
The Co2 system is also an easy system for the hobby worker to use, it is frequently used in trade schools or colleges for foundry practice instructions because of the basic equipment requirements, small batches of moulding sand can be readily made up.
Generally it is quite easy to use, and repeatable results are not difficult to achieve. However there is one thing that can be detrimental to the Co2 performance and that is if any excess moisture is contained in the sand, moisture levels above 0.5% will impair the performance of the sand and give poor moulding results.
One drawback with co2 is the rental cost of the gas bottles, and the expense of gas cylinder regulators required for correct gas line pressure. Sand consumed in the moulding process is usually discarded after each use, which could present a problem if you are constantly casting.
The Self-Set moulding Process.
The self-set system is also very easy to use, all you need is good clean foundry grade sand, a silicate resin to mix with the sand and a catalyst to create the reaction in the silicate, which normally takes around ten minutes on a warm day.
The equipment required consists of: A mixer, a small hand held power drill fitted with a simple paint mixer will suffice. And an accurate digital kitchen scale to measure precisely the chemicals you'll be using.
The silicate is quite expensive to buy, and is supplied in 20 litre and 200 litre drum sizes, the hobby foundry worker may need to cultivate a friendship with the commercial foundry operater in your area.
