Castable Firebrick Homebrew recipe

[peteH]

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? 

[vtsteve]

The second one is the correct one. The mix with the higher percentage of sand is less likely to shrink/crack.

[TXCraig1]

You might get more responses with a different subject title. Nobody is going to read "homebrew recipe" and think anything but beer regardless of what forum you post it in.

[bradtri]

I prefer to have as little sand as possible  in my beer.

To at least add something of value, the forno bravo build forums are very active and might be a good place to also ask this question. 

https://community.fornobravo.com

[Tscarborough]

It has been answered over there many times.  The second is the correct one, but either will work to a certain extent.  With either you should use stainless steel needles for the best result.

[peteH]

Can you tell me where to get the stainless steel needles and how much to use?, thanks!

[vtsteve]

Ebay, 3-5% by weight. Just google "stainless steel needles for concrete" or "stainless steel needles for refractory".