I modified the subject line as there was a concern it might be confused as a misrouted beer forum post (although pizza and beer go together perfectly!). So I have seen 2 recipes on the forum for homebrew castable mortar, either 3:1:1:1 or 6:1:1:1 (sand:portland:lime:fireclay). What is the difference between the two (besides the obvious), is one better than the other?