I would tend to agree with Donna, but without knowing what your debris
looks like, its hard to say. It is a good practice to filter Hematoxylin
frequently. Hematoxylin precipitate appears as dark blue/black granular
debris anywhere on the slide, usually visible only microscopically,
unless you've really had let the scum build up.
Katri

Katri Tuomala
Anatomic Pathology
St.Joseph's Hospital
Hamilton, Ontario, Canada