With regressive and modified progressive staining, a differentiating solution is used. If the differentiating solution is made in-house, there is the potential for it to be either too weak or too strong. Both scenarios will impact staining. If the differentiating solution is stronger than intended, it will remove more hematoxylin and will make the nuclei pale. If the differentiating solution is too weak, nuclei will be under-differentiated and will appear to be over-stained and uncrisp.
Time is also an important factor. Too much time in a properly prepared differentiator will also remove more hematoxylin and will ultimately leave the nuclei understained.
