I'm a student learning how to prepare blood films and today I was curious about something, so I performed an experiment.
After preparing a thin blood smear and drying it (no staining), I took a look under the microscope (at a total magnification of about 200X... I have a cheap microscope). Even though it was zoomed out, the red blood cells were easy to distinguish. The cells were clear but they had dark edges.
Then, I blew some hot air onto the same slide, causing the dry smear to absorb some moisture. Then I let it dry once again.
I observed the same slide under the microscope once more, but this time, I could barely make out the red blood cells. They were certainly still there, but their features/borders were extremely hard to make out and distinguish.
I'm wondering what causes this. Are the cells absorbing moisture and thus changing their morphology? I couldn't find any answers online, so I thought I'd ask here.