Here's a subject dear to my heart.I'm one of those histotechs who tries to
get the most mileage out of my solutions. By close monitoring of microtomy
and staining characteristics, I have found that it is not at all detrimental
to use the same two baths of xylene for up to four weeks, 5 days per week.
Over twenty years I have done this stretching act on a Technicon duo, later
on a VIP, and most recently on a Shandon Path Centre for up to four weeks
processing 40-90 blocks per day including numerous breast and skin
specimens. Even though the solutions get quite yellow, they function very
well for three and sometimes up to four weeks as long as absolutes and
paraffins are rotated weekly, or maybe after a week and a half. If you are
careful and observant, it really is possible to stretch out the useful life
of xylenes. My xylene waste per month is just under two gallons (7500
surgicals/year). We use limonene to purge and stain. Just my experience.
Jeff Silverman