The Choice Between Aluminum Silicates and Fused Silica for Stucco
The use of Aluminum Silicate stucco as a replacement for Fused Silica stucco is investigated. Two different types of backup slurries and three different stuccoes were evaluated. A new test is described and used to measure the ability of the slurry and/or stucco to build a uniform shell thickness. Much of the economic advantage of Aluminum Silicate stucco is lost when other factors are considered.
Many investment casting foundries use fused silica based slurries with either fused silica stucco or Aluminum Silicate stucco. Invariably, the reason given for using Aluminum Silicate stucco is that the price per pound is roughly one half the amount for fused silica sand. However, in addition to the price per pound, there are other issues to consider that affect the overall economics of this decision. These include: