I've installed the mod Furnace Mk2. It has pics for its recipes, but the one for the insulation amplifier is rather vague. I've figured out that the corners are sand and I'm pretty sure the top and bottom center are smooth stone due to similarity with the recipe for the furnace itself. But the middle row is a mystery! I've tried iron blocks, white wool, clay blocks, quartz blocks...all to no avail. All I can tell is that they are predominantly whitish gray. The images shown are screenshots and so have no hover text to indicate what kind of block each one is.
You'd think the crafting table would tell me, but something is wrong with the release of recipes and they don't come up until you use them. Perhaps that's why they posted the pics.
Does anyone have any information about this recipe? I'd really appreciate the help! It has otherwise been a great mod so far.