Actually rebar mesh does not suit castable refractories. Because the steel is way more conductive it will attract the heat to itself and expand more than the refractory that surrounds it leading to fractures in the refractory. To get around this problem the recommended reinforcement is stainless steel melt extract fibres or more commonly referred to as stainless needles. Because they are dispersed randomly in the castable and each individual fibre has less mass than a thick chunk, the surrounding refractory has a chance to absorb their heat eliminating the temperature difference of the two materials. Normal steel is also subject to rust especially in conditions where it is subject to heat.galvanized steel is a bit of an unknown quantity in a WFO because zincs melting point is around 400C, a temperature that is achievable, so who knows what happens to the coating.The stainless needles are a bitch to handle, needle sticks are frequent, but not too bad.You do get used to handling the mix gently and respectfully.Hope this helps.