Green sand, sometimes referred to as clay, is wet sand that has been placed in a mold and packed down. The benefit of using green sand when casting is that the sand is in its uncured state when the metal is poured. One of the reasons that green sand is so commonly used is that the sand can be reused — making it an inexpensive alternative to other sand casting materials.

While green sand is incredibly cheap to use, it can shift or collapse during the casting process due to the unstable nature of wet sand. That being said, the cost-effectiveness of this sand casting method is greater than the likelihood of the cast shifting — meaning that green sand casting is a favorable method of prototype creation and is likely going nowhere soon.

Sodium silicate is another substance that is commonly used in casting. Sodium silicate is a unique substance because it can be changed from a liquid to a solid extremely fast when it is introduced to carbon dioxide. The largest benefit of using sodium silicate casting is that it works well with casting projects that require a cavity.

While incredibly reliable, sodium silicate needs to be mixed with other materials in order to ensure that the cast can breakdown and the core can be removed. If the materials are not mixed, the cast will be rendered useless.

Resin becomes solid with a smooth finish when it is heated. Because of this, using resin sand for castings can ensure that the cast surface remains flawless and free of imperfections. While resin sand is the material that produces the highest quality casts, it is known to be substantially more expensive and time consuming that green sand and sodium silicate. Silicate sand molds are most often used in situations where the cast must be absolutely perfect.