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.
