The best answer is AIR CONDITIONING, but if you are not in a air conditioned space we suggest flood coolant. Regular usage of flood coolant will keep any rust from forming on your plate. The coolant has Rust Inhibitor chemicals in it to aid with this. The Hot Black Oxide really helps with the medium carbon as well. The 4140PH subplates are high in molybdenum and chromium and do not rust easily. If you care concerned with the space between your machine table and your modular plate we suggest CLP® Cleaner, Lubricant & Preservative. Many of our customers use it and we now offer it in a small bottle for $9.95 with a modular subplate.