ArtMetal

Although most of my sand casting experience is with Linocure (a two part resin), I can tell you that it is common practice to add a healthy percentage of sawdust into the mix for cores.

I guess the porosity helps improve venting (maybe), but it helps substantially with evacuating the core after casting. I`ve also heard it argued that the combustible wood helps keep the metal hot (an issue with iron and cold molds), but I`m not sure I believe that.

I read a wikipedia article last night about pre-cast ceramic shell cores...can you build or cast the wax around a ceramic core?

Bill Wolff
www.billwolff.net