Found Dreaming

Any shrinkage cracks

I noticed 4 fine cracks about 90* apart from each other, no more than a hairs width. These pose no worries for me, the wall is so thick they are not going anywhere.

the refractory is going to crack if it doesn't it can't relive the stresses that build up during firing, if its thick enough it should stay in place and act like refractory and insulate the wall, my big blue furnace if you looked in it you would say that the wall was going to fall out, but as burnt as it is and cracks running everywhere I can still lay my hand on the outside wall where the flame inpinges on the inside.