High Fire Clay (cone 9-10)
50 lb. New FHC
25 lb. Hawthorn Bond
10 lb. Kaolin
10 lb. Ball Clay
5 lb. G-200 Feldspar
=100 lb. dry materials
+ water, + slop
 

Optional: 5 lb. sand or grog (Use sand or grog for large work.  Upside: it helps keep large work from cracking. Downside:  it adds grittiness while you are throwing.)