Some of the only DOS I've ever had was from curing on "stainless" cookie cooling racks. The problem with so-called "stainless" racks, especially the smaller ones made for cookies, is that they are really just coated with stainless. Underneath is cheaper metal. Over time, as the wire bends, get knicked, is scrubbed, etc., the stainless coating gets thinner and thinner, or even flakes off. Then your soap will be exposed to the metals underneath the stainless, and these will cause DOS. So if you want to use inexpensive stainless racks, be sure to put something underneath the soap.