Freshly sectioned tissue slides should be dried standing up to let water run down from underneath sections. Tissue sections that are cut for special stains or immunohistochemistry (IHC) should be dried at room temperature prior to staining applications. Unstained slides that require transportation or storage should not be deparaffinized or heated in a slide dryer, since the paraffin acts as a protective barrier for the tissue.
Slides should be placed in a slide dryer or oven for 15-20 minutes to dry out water before deparaffinization. Slides can also be dried over night at room temperature to allow tissue to adhere better to the slides.
The temperature of drying ovens should be at, or just above, the melting point of paraffin. This is typically around 62° C for proper adherence and deparaffinization of tissue sections.
High drying temperatures will boil water under the tissue section and lead to nuclear bubbling.
High temperatures will also melt fatty tissue components in tissue sections, especially brain tissue.
If tissue sections are not dried properly before staining, they have a greater chance of lifting from the slides and even falling off during the staining process. Tissue lifting will most often occur with brain sections, nail clippings, bone sections, and poorly processed tissue samples.