I purchased some pre slacked lime in dry form from Virginia Lime Works, part of their mix and go line. I just needed to add sand. It was not putty. I had a few bags left over, afraid they would go bad, like the typical bag of cement left in the shed for 5 years, I mixed it up into a putty and stored it in a big plastic tub. I did this with the understanding it would last in the putty form. It was topped off with a couple inches of water to keep it from drying our. After almost two years I now have a nice light blue, hard, smelly lime block. Apparently the mix and go does not work like the raw putty lime does. I have a couple bags in the dry form which I am hanging onto to they have not gone hard, yet.
I heard NASA was watching a new big green shape in space, whatever it is, it's probably long gone or changed into something different, like my putty.