DARVAN® 811
DARVAN® 7-N is recommended for use in the preparation of casting slips made from whiteware and refractory compositions, producing slips with a wide casting range. The slips show little tendency to thicken on standing, or to become thixotropic. Ware cast from these slips is very plastic and easy to “scrap”.
Most whiteware bodies are readily dispersed by the addition of 0.2 to 1% of DARVAN 7-N, based on dry body weight. During the casting process, very little DARVAN 7-N is absorbed by the molds and, under most factory conditions, a good casting slip can be made from 100% scrap just by adding water to give the desired fluidity. Compared to the use of sodium silicate and soda ash, DARVAN 7-N enables longer life for plaster molds.
Both drain and solid castware made from slips containing DARVAN 7-N can be left in the molds for long periods of time without cracking. Hobbyware consisting of difficult shapes is made successfully on a commercial scale by leaving the ware in the molds for 6 to 24 hours. If the ware is to be left in the mold for a long time, the drain hole in the mold must be covered or the mold inverted onto a flat surface in order to prevent surface drying around the drain hole. A long set in the molds produces ware that is very easy to handle, and decreases the tendency of large pieces, e.g. vases, planters or sanitaryware, to warp or distort while drying. Ware made from slips containing DARVAN 7-N can also be removed from the molds in the usual time of one to two hours, with the exception of heavy types of solid casts.
DARVAN 7-N provides sprayed glazes with outstanding viscosity stability. In ceramic compositions it can be used where sodium oxide is not detrimental, such as casting of barium titanate, zirconium oxide and aluminum oxide. In spray-dried bodies, in addition to its dispersing properties, it can be used as a binder at levels of about 2%.
DARVAN 7-N has been tested in various applications as a grinding aid. Depending on the application, 0.005% to 0.1% has been reported to help dry grinding.
DARVAN® 811 Dispersing Agent is intended for industrial and
agricultural use only. This product is not intended for other uses, such as for
pharmaceuticals or cosmetics.