What is the purpose for the stainless steel fibers that are mixed with the castable refractory?

You could build your oven with just Castable Refractory and it would be rock solid. But our stainless fibers are the secret ingredient for a bulletproof wood fired oven! These jagged little 2" fibers act like thousands of tiny little rebar when they are mixed with the Castable Refractory. So if your oven should happen to get a hairline crack, the stainless steel fibers will hold the oven firmly together and keep the expansion to a microscopic level.