Product Code : ET-9548
Brand Name : Edutek
A slide ringer can be used for several things. If you've got a diatom test slide from Klaus Kemp you will note a small "finder ring" around the 8 diatoms to help locate them quickly. In addition, the edge of the round coverslip is sealed to the slide very neatly, again using a ringer.
On coverslips that I ring, I let the dark colored edge sealant dry, then add a thin white ring on top to allow identifying the top of the slide while not wearing glasses.
Another use is making support rings to prevent crushing a specimen when applying the cover slip. This was my original motivation since I wanted to make whole mounts of deer ticks without mashing them in the process. I tried using punched paper (lots of stray fibers) and punched tape (melted by xylene in the mountant) with poor results; shellac rings are easy to make and work very well.