Machinable wax

My first attempt at making machinable wax. 

Using rawkstar320's recipe and directions from Instructables, I combined paraffin and polyethylene. Then I used a wood lathe fitted with a vacuum chuck to turn the plate models (dark gray). I did the middle one first as proof of concept and made a plaster mold of it (white). The light gray plate was formed by pressing clay into the plaster. Ultimately, I plan to carve the wax and use a potters wheel to force the clay into the plaster mold. 

I tried carving the wax and found it only ok. I believe the mottling you see is due to some of the polyethylene not fully dissolving into the wax. This made for hard and soft variations in the final product. Also, none of it was as hard as the Matt green wax that I am use to carving for my jewelry models.  Is it possible they use additional ingredients such as microcrystalline or carnauba wax?