| Using a Sodium Silicate Pottery Technique to Create Cracked Texture |
What is Sodium Silicate?
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Sodium silicate is also the technical and common name for a mixture of such compounds, chiefly the metasilicate, also called waterglass, water glass, or liquid glass.
Sodium silicate is a generic name for chemical compounds with the formula Na ₂ₓSiO ₂₊ₓ or ₓ·SiO ₂, such as sodium metasilicate Na ₂SiO ₃, sodium orthosilicate Na ₄SiO ₄, and sodium pyrosilicate Na ₆Si ₂O ₇. The anions are often polymeric. Sodium silicates are non-flammable, non-explosive, and non-toxic. They are, however, alkaline materials and pose hazards to the skin and eyes. The physiological effects of contact vary with the alkalinity of the silicate involved, and range from causing irritation to causing chemical burns. Darvan 7 = Alternate to Sodium Silicate
Darvan 7 is a deflocculant that is similar to sodium silicate. However, unlike sodium silicate, Darvan 7 does not erode plaster molds. As a deflocculant, Darvan 7 weakens the electrical attraction between clay particles and thus acts as a thinning agent in slips and as a general dispersing agent for clay bodies and glazes. It is mainly used to enhance the fluidity of casting slips and maintain or slow the shrinkage rate. Darvan 7 is typically preferred with porcelains and high iron content clay, while Darvan 811 can be used for stoneware, high fire slips and red low fire slips. Slips that are prepared with Darvan 7 show little tendency to thicken on standing, which is why it is often used in glazes. Darvan 7 can also be added to joining slip, which is ideal because it allows one to use less water and results in less shrinkage at attachment points. |
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