I have been wax carving up a storm. Now the "greens" are in the can. Next step is fill the cans with investment, then pop them all into the oven for a good bake. Takes about 12 hours with a max temperature around 1250 degrees. That cooks them good.
I have a couple of more carvings but I have limited space in my kiln. I have never tried to do four at one time and I am not sure if they will all fit. I have fired three at one time so will do at least that many.
The white material is called investment. It is a special plaster and silica mix that will bake into a ceramic like material that forms the the silver into the shape of what was once wax.
Here is a link to the article: http://workshop.ramblindan.org/jla/lost-wax/casting/casting-five.