What are you doing with the blood smears?  Giemsa, Wright-Giemsa,
Wright stain????

We fixed our blood smears with pure methanol for 10 minutes IF they were
going to be held for the above stains.
HOWEVER, our best results --------
with any of these stains was to do a regular blood smear technic,
without prefixation since the stains, purchased in stock solution, contains
the methanol.  The fixation occurred when the stain was put on the smear
(by methanol), stained for 6 min, then buffered, rinsed and air dried.
THESE direct fix/stained smears were far superior to any prefixation in
methanol then stained.   If we prefixed, we had to adjust the time for
diluted, buffered Giemsa - depending on what we were looking for.

I am second quessing what you are doing with the smears, but hope this
helps.

Gayle Callis