Hi,
    Just a shot in the dark here but do you use tap water to rinse off the
hematoxylin? It could be an iron deposit from rusty water. A good way to narrow
off the possible culprits would be to start from the beginning and change
things
leaving everything else the same. Try using distilled water in your float
baths.
Do you use a slide etcher to label your slides? that could leave the slides
dirty.
    My guess would be your hematoxylin. Try a different lot of the stain.
Filter
the hematoxylin daily if not more. Change the hematoxylin more frequently,
once a
week seems a little conservative for any quality.
good luck
Amos Brooks

ALICELT@aol.com wrote:

> Recently we have been getting black junk on our slides. We use a Sakura 601
> automatic stainer. We stain about 600 slides a day. It does not seem to be on
> the tissue just around it. We change our hematoxylin three times a week and
> chang all other solutions daily. We do recycle the xylene. We use tap water
> in our baths. If you have any suggestions Please help.