Green Sand Metalcasting Foundry News

W, X, Y, Z - Foundry Additives Glossary

WAD ORE (See: MANGANESE DIOXIDE) 

WATER GLASS (See: SODIUM SILICATE) 
"Sodium silicate," "soluble glass," and "silicate of soda" are all called "water glass." Water glass is a composition of various ratios of Na, O to SiO, in dry crystalline or hydrated form. It is used as a binder in mold and core sand mixtures. The Carbon Dioxide (C0₂)-Sodium Silicate Process is used by the foundry industry. When 2% to 4% sodium silicate (Water Glass) is added to a clean silica sand or a refractory sand and carbon dioxide gas is passed through this formed mold or core, it hardens into a refractory mass, making excellent cores and molds for certain castings. Sodium silicate dissolves in hot water. Sodium silicate (water glass) is made by melting sodium carbonate with silica or by applying heat and melting sodium carbonate together with sand, charcoal and soda. This product, fused sodium silicate, is then ground and dissolved in boiling water for use as a foundry binder. Sodium and potassium carbonate can also be made into a double soluble water glass. 

WATERLESS BINDERS (See: NEO-BOND)
Neo-Bond is a waterless binder which is very popular in the foundries where waterless binders are required. No temper water is necessary. Five percent (5%) by weight Neo-Bond, plus less than 2% of a high viscous coastal oil is all that is required when mulled together to form a waterless molding sand mixture. Waterless binder mixtures have produced, and are producing castings, with better detail than more expensive processes such as shell molding. Such waterless mixtures are molded "green" and are generally a low cost repetitive operation. Waterless binders, such as Neo-Bond, are used with fine silica sands, olivine, zircon, or Hevi-Sand mixtures.

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V - Foundry Additives Glossary

VEGETABLE OILS (See: CORE OIL-COTTONSEED OIL-LIN­SEED OIL-OILS-TUNG OIL)
These are oils obtained from plants. They are used in the foundry as drying oils, as lubricants, and for other purposes. Examples of vegetable oils are linseed oil, cottonseed oil, olive oil, palm oil, and castor oil. The chief distinction between vegetable oils and fats is physical. Oils are fluid at ordinary temperatures. Vegetable oils can be thickened by oxidation, or more simply by blowing air through them. They may be hydrogenated by passing hydrogen gas through them. in the presence of a catalyst. Foundry oils contain a large quantity of the vegetable oils sold.

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T - Foundry Additives Glossary

TALC (See: SOAPSTONE)
Talc is a hydrated magnesium silicate with the composition [4SiO₂ 3MgO • H₂O]. It is a soft, friable mineral having an oily touch. It has a Moh's hardness of 1 and a specific gravity of 2.8. It is referred to as "soapstone." It is used as a parting compound when impregnated with wax and ground. It has been used in nonferrous mold coatings, ladle refractory coatings, and when blended with clay, bentonite, cereal or dextrin, it is used as a core paste. It is used as an additive in various core compounds and core fillers.

TANNIC ACID (See: BINDERS-CORE BINDERS)
Is prepared from extraction of the liquid squeezed from wetted oak bark. It is rarely, but sometimes used as an auxiliary binder in core sand mixtures where clay is present.  

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