Hi BadPlumbing
I used to use a wafer, because that was how I was taught. My stoma has an aperture which release output directly onto the skin, so I need to get the opening of the bag as close as I can to under that point, to minimise tracking under the adhesive part of the bag. My stoma nurse then recommended that I stop using a wafer, because that is just another layer that raises the opening of the bag away from the aperture. Since I did this, my skin irritations have reduced dramatically, however I do have a patch of bad skin where the top layers of skin seem to be gone completely. I need to get this seen to because I cant see how that can end well going forward.
I would not go back to a wafer unless I need to use a bag that has a larger stoma opening (my current size is 25 mm and I have a supply of 30 mm bags for emergency) and then only a wafer with deep convexity.
Hope that helps