I have acquired some rock hard clay! Joy... This is a 25lb block. Dry. Solid rock. I have 3 of these to try to rehydrate. I started with one already and had some fair success and did so quite simply.
I've done my fair share of research on how to rehydrate clay, asked some seasoned potters, and such. Much involved drilling holes, or putting it in a bucket to turn to mush.
I wanted something that wouldn't require TOTALLY reprocessing the clay. So on a whim I poured some water in the bag with one of the rocks. Dug a couple divots in the top and added some water. The divots were maybe a half inch deep, if that. I then tied that bad boy shut TIGHT! All the water went to the corners of the bag which is not optimal...I put it in a small tote and squished it to one side so the water level was most of the way up the side of the clay. Added some other items to keep it mushed.
I let it sit a few days, cracked it open today, flipped it while still in the bag, divots are now down. The clay that was at the bottom? Now viable, albeit wet, clay. After about 20 minutes out the 3/4 inch slab was dry enough to roll and form.
One of 5 pieces I was able to get out of my slab. These are drying and will go into a bisque fire so I can get a feel for how this stuff faired. This clay is actually pretty infamous, it's been floating around my parent's house for probably 20 years, my mom claiming she threw it in the back yard ages ago because it was dry. Well due to flooding it was found! And now I'm the proud owner of some age old, brand new, clay that happens to be low fire and the brand I use!