[Histonet] Uneven Staining

[Elizabeth Cameron]

We are doing a Hale's colloidal iron stain (no counterstain) on serial sections of mouse kidneys.  We are staining an entire kidney at a time (about 90-150 slides), and after many successful runs, we are now finding some slides in each batch with very uneven staining.  Half of a section will stain as it should, and the rest of the section is very pale.  It seems to be in a similar area from one section to the next, but not exactly the same area.  It does not look like a deparaffinization issue.  There may be two or three slides in a row like this, or just one section on a slide, followed by 30-40 that look fine.  The sections are 6 microns. Any ideas on why this might be happening?  Thanks!

Elizabeth M. Cameron, HT, QIHC (ASCP)
The Jackson Laboratory
Bar Harbor, Maine
(207) 288-6561