Gresham, yeah I thought about the diapers too, since I have hundreds of them, some of which are too small fir my kids now (half bags of preemie diapers etc). I was worried that they might have some deodorizing thing in them. But if it's safe for a baby's butt, it probably won't do much harm sitting in a bucket with salt, also if you think of it, why would diapers have any deodorizing feature? They stink and you change and toss them!
So what are "p2" crystals?
Oh and I discovered that if you DO want to reuse a block of salt, it's easier to break up if you slide the block out of the bucket and into a LARGE washtub, then go at it with a screwdriver/chisel or ... drill. (make sure to wash and dry the tools right after!)
V