Re: Kato clay...

I know that I've seen questions re: Kato clay previously, but cannot
remember the exact 'fix" for this problem.
I purchased the Kato clay samples, and am finally finding the time to "play"
with the clay.
It has been stored with all my other clay... Premo, Sculpey, and Fimo... in
a temp controlled home.
The Kato clay is like a rock. I've tried to mix it with other clay so that I
can work with it, but to no avail. It crumbles and I'm getting nowhere with
it.
The other clays were purchased at the same time, and they are fine.
Is there anyway I can salvage this clay?
Help...
Thanks in advance... Louise