The fully gated wax is next taken to investment. Investment is a process whereby the wax is dipped into liquid ceramic slurry and then coated in aggregate materials. There are two types of slurry and aggregate, the first of a very fine grade to pick up all of the details and textures on the surface of the wax and the second of a more course material to build up the strength of the ceramic shell. Investment requires the application of several coats of ceramic shell. As each coat must be thoroughly dry before a subsequent coat can be applied, the whole process can take several days. Below, gated waxes in various stages of investment.