1. Generally moulding sands can be classified as:

          (a) Natural Sand

          (b) Synthetic or High Silica Sand

          (c) Chemically Coated Sand

          2. According to amount of clay, moulding sand can be classified as :

          (a) Silica Sand                                    - up to 2% clay

          (b) Lean or Weak Sand                      - 2 to 10% clay

          (c) Moderately Strong Sand               -10 to 20% clay

          (d) Strong Sand                                  - up to 30% clay

          (e) Extra Strong Sand(Loam Sand)    - up to 50% clay

          3. Other type of Moulding Sands

          (a) Green Sand or tempered Sand : It is a mixture of silica sand, 18-30%  

                clay and 6-8% water. It is fine, soft, light and porous.

          (b) Dry Sand : Green sand that has been dried or baked after the mould is made is known as dry sand. It is suitable for larger castings.

          (c) Loam Sand : It is high in clay up to 50% or more.

          (d) Facing Sand : It creates the face of the mould. It comes into contact with the molten metal when the metal is poured.

          (e) Backing Sand or Floor Sand : It is used to back up the facing sand and to fill the whole volume of the flask.

           (f) System Sand : It is used to fill the whole flask.

           (g) Parting Sand : It is used to keep the green sand from sticking to the Pattern and also to allow the send on the parting surface of the cope and drag to separate without clinging.

           (h) Core Sand or Oil Sand : It is utilized for building cores.