We use sponges often when making windows but I've seen a problem developing that I'm going to call out. These Scotch Brite sponges (and their knock offs) seem to be everywhere now and for good reason-- that scrubby green or blue side is very handy when washing things The problem is that the green or blue side is a piece of soft but scrubby plastic fibers that cover the sponge and allows very little water to pass.
So, when putting a piece of sponge in your Soldering Iron Holder make sure that the scrubby side of the sponge is down and that the sponge itself faces upwards (as seen below). The same holds true when cutting a new piece of sponge for your grinder. The sponge itself should be against the grinding wheel, not the green or blue scrubby side. If the scrubby side is against the grinding wheel it is actually preventing water from getting to the wheel.