ArtMolds Sodium Silicate
Sodium silicate is the common name for a compound sodium metasilicate, Na2SiO3, also known as water glass or liquid glass. It is available in aqueous solution and in solid form and is used in cements, passive fire protection, refractories, textile and lumber processing, and automobiles. Sodium carbonate and silicon dioxide react when molten to form sodium silicate and carbon dioxide This technical bulletin discusses just a few of its many applications for the user in, ceramics, metal mold making, concrete and plaster sealing and adhesives.
SUMMARY OF ADVANTAGES:
● Low cost
● Resistant to temperatures up to 3000o F
● Odorless and non-toxic
● Moisture resistant
● Bondable to metals, particles (e.g., refractory materials), fibrous materials (e.g., paper, fiberglass), glass, ceramics
● Strong and rigid
Ceramics Applications Instant Antique Finish: Brushing the surface of a thrown pot with sodium silicate, quick-drying the surface with a heat gun or blowtorch until the surface no longer is tacky, then expanding the form from inside can give a piece of pottery an aura of instant antiquity. The sodium silicate forms a thin skin that, with applied heat, quickly hardens on the surface, encasing the so) and therefore, till malleable, clay cylinder beneath. Normally used as a deflocculant for casting slips, in this use it is quickly dried to the touch with some heat from a blowtorch. At this point, it is like a candy apple, crunchy on the outside and so) inside. When the form is then expanded with pressure from inside, the skin surface cracks enlarge in size depending on the amount of pressure and expansion. The residual sodium silicate gives a slightly glazed surface like a thin salt-glaze. The essence of the process is in the speed with which it is done, as the coating needs to stay hardand not absorb moisture from the so) clay beneath.
Clay Slip Deflocculant: Sodium silicate is the most common economical and powerful deflocculant for clay slip as it reduces shrinkage. Initial additions of sodium silicate serve to thin (deflocculate) the batch. However, there is a point after which sodium silicate starts to have the opposite effect, actually making the batch thicker (flocculting it). Compounding the difficulties is the fact that sodium silicate accelerates its effectiveness as it nears the point of over-deflocculation. For example, you might add one ounce to the batch with little improvement in Viscosity, but the fourth addition will send the batch over the limit. That is why it is recommended to use small additions until you are familiar with slip making. ; If you add sodium silicate and the slip gets thicker instead of thinner, it is over-deflocculated, and you have two options: you can try to recover the batch or throw it away. If your slip is badly over-deflocculated, it is very difficult to correct and will cost you more in time and frustration than the purchase of new slip. If the batch is slightly over deflocculated, you can bring it back with the addition of more dry material. Determining the correct amount will be trial and error,but with every clay addition, you should mix the batch for the fully recommended _me (i.e. 3 hours for a 300 lb. batch). If you believe you are close to over-deflocculation, it is time to switch from sodium silicate to dispersal. Dispersing agents such as Darvan can be added after you have added the maximum amounts of Sodium Silicate. Typical Clay Slip Formula: · Clay Blend 100 lbs. · Barium Carbonate 1/2 ounce (14.75 gr.) · Soda Ash 1 ounce (23.35 grams) · Water 5 gallons (19.50 liters) · Liquid Sodium Silicate 5 fluid ounces.
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