I use a photo sponge instead of a squeegee too. Squeeze it until just damp and wipe it gently on the negative, 35mm or 120. I have never had scratches, but do keep the sponge very clean. That will adsorb the moisture out of the sprocket holes.
Also, I dilute the wetting agent much more than recommended. I had problems with Newton rings and more dilution seems to have eliminated that.