Lorraine,

Some controls definitely need to be cut "fresh" while others seem able to
withstand being cut for months or even years. The controls that seem to fade
quite rapidly in our hands are ER, BCL2 and CD30. We only cut enough of
these for at most one month. Sealing with wax appears to be unnecessary. Our
blocks are several years old and still stain well without being sealed.

There was a good article in the Journal of Histotechnology which looked at
this problem in more depth. I will try to find it and give you the
references. Tom