saffron and humidity

From:Patrick Paulusse


I am running an HPS stain as my routine stain on a Leica Autostainer.  I
find that sometimes I get inconsistent saffron staining (little to no
staining).  In the protocol, I have 1 - 95% followed by 3 - 100% alcohols
that dehydrates the slides (total time in these solutions is about 10
minutes) before the saffron.  We run approximately 80 - 120 slides per day
and the inconsistency appears for the entire run - meaning that there is no
difference between the first rack and the last rack.  These alcohols (as
well as all our other reagents - except the stains) are changed daily after
we are finished staining and left approx. 24 hours for the next days
staining in reagent containers that are covered with loose fitting covers.
The humidity in the lab can run between 50 - 70% depending on the weather
(our humidity is not controlled).  The saffron is used for 3 weeks and then
discarded.  My theory is that the alcohols before the saffron are absorbing
minute amounts of moisture during periods of high humidity while they are
sitting for 24 hours and are therefore having a deleterious affect on the
saffron staining. Using fresh alcohol from a tightly closed stock container
improves staining.  I am having trouble convincing others of my theory and
would therefore like to hear what others think about the validity of my
approach - or am I barking up the wrong hygrometer.

Thanking you in advance,

Patrick Paulusse
Histology Supervisor
Pembroke General Hospital
Ontario, Canada

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