Hi. In my experience doing immunos on slides, any area of a section that comes off of the slide surface will be more strongly labeled and I don't think it's because antibodies get trapped but rather because they have access to both surfaces of the section in those areas. For instance, it will also happen if a section comes off at the edges. What causes these small areas to not stick to the slide properly? It looks like you could be trapping air bubbles while collecting the sections which prevents these small areas from sticking to the slide. Air bubbles can be very small, like only visible under a binocular. Is that a possibility? (Cryostat? Paraffin?) If not air bubbles, could it be other impurities on the slides before you collect the sections? (dust?)

Thank you! That is helpful. It may be trapping of air bubbles or debris, like you mentioned. We have also been vacuum sealing our unstained slides to prevent oxidation of the tissues and preserve the antigens. Maybe the suction from the vacuum sealer is causing this lifting? I would expect lifting on the edges if this was the case, so just a thought. I will have to continue troubleshooting.