After the tree is assembled, it is ready to have the ceramic coating applied. This is done with a single coat at a time and with a slurry coat of ceramic in conjunction with a dry ceramic stucco coat. Each coat must be dried thoroughly before the next coat can be applied. The types of ceramics used do vary from foundry to foundry and will determine the drying time needed along with the number of coats required. Different slurry mixes are also used for primary coats verses back-up coats as do stucco sizes. The stucco is normally applied with rainfall equipment or fluidized beds. The Investing / Stuccoing process can be automated for high production parts. The ceramics and their understanding are a key element to making the process commercially advantageous. They must be relatively inexpensive and produce a shell that has the physical property of no linear expansion with temperature changes over a three thousand-degree temperature range.