Ervin,
dririte can, theoretically get sucked up in the pipes and clog them.  Even
though we have been warned not to, we use 1.5% cobalt chloride (Use 100%
alcohol to make this) in our VIPs.  Just put about 100 ml per Vip container
(or as much as it takes to get the blue color you like in your tissues).
You are not supposed to this because it causes a precip on the rotatry
valves and tubes in the processor, but we have been doing this for 5 years
at the hospital where I work with no problems as long as we keep up with our
weekly hot water flushes.
Feel free to contact me with any questions,
Wanda Shotsberger
(HT ASCP)

-----Original Message-----
From: Ervin Shaw [mailto:shaw@lexhealth.org]
Sent: Tuesday, February 29, 2000 8:48 AM
To: Histonet List (E-mail)
Subject: Drierite


Hoping to keep our last Tissue-Tek VIP 100% alcohol as close to 100% as
possible, we had considered putting Drierite in it. But, Dr. Freida
Carlson's text, p25, warns not to use Drierite in a closed system. Does
anyone know why not? For optimized specimen orientation and block economy
(several ordered/oriented specimens in one block), we (since 1978) pre-embed
small specimens in agar; and if dehydration is not complete, it apparently
microscopically "boils" the water in the agar causing it to shrivel and
collapse into a tough-to-cut, plastic-like material.