the mineral oil way makes drying unnecessary. when the disk needs cleaned, a toothbrush and naphtha or isopropyl does the trick. i have cleaned with wd-40, but it creates more of a mess than the other 2.great question, as a faceter i have been using these type of disks for some time now, i have found that water and a small amount of dish soap "one drop to a coffee can" is the cleanest and safest coolant to use. it cleans up great, washes away fines and suppress dust. how ever when finished please wipe your disks dry, or at least spin dry then. all diamond laps will rust if you neglect them. and at $130.00 to $250.bucks a pop that can hurt the old wallet. there are topper laps at $15.00 to $30.00 each, you need to use a master lap $25 to $ 30.00. a great resource is www.saleskingsleynorth.com
i have used this company many times in the past.