I'm working on building a cementation furnace and I already have a beehive kiln, but I'm curious about a couple things - first, the refractory bricks for my kiln just never seem to get damaged, no matter how much I use them. Have I just gotten extremely lucky, or does the kiln not break down the same way as cementation furnaces do? Second, can I use different tiers of bricks in the same furnace? I have some crushed chromite to make tier 3 bricks with, but not quite enough for the whole furnace, so I'd love to finish it up with some low tier ones to get some steel going while I go looking for a new chromite vein (I felt very clever getting chromite before getting steel - I have a decent supply of ore blasting bombs that I used to blast the vein I found while hounding for olivine).