The steamer worked. I used a piece of cardboard as a shield while I moved the nozzle along the door sill plate. The steam made the protective film wilt and release from the adhesive. I could peel the film easily off in a few big pieces and the remaining hardened adhesive came easily off with Goi Gone.Wipe Away the Grease. Dip a sponge or soft cloth into the solution, and wring until it's not dripping. Wipe away the grease following a grid pattern or the grain of the metal, so you won't miss any areas. Rinse the sponge in the cleaning solution frequently to prevent redepositing the grease. The Spruce / Almar Creative. Method 2: Copper Penny and Penetrating Oil. Closely examine your gun to find specific areas of rust. Spray a cleaning and degreasing lubricant on those spots. Let it sit for a half-hour or more. Use a penny to gently scrape the rust off the surface. Wipe off the areas using a clean cotton rag or microfiber cloth.
Phosphoric acid will dissolve iron oxide without attacking the other components of the steel (chromium and chromium oxide, nickel, and iron). The rust is dissolved by the following reaction: 2 𝐻3𝑃𝑂4 + 𝐹𝑒2𝑂3 → 2 𝐹𝑒𝑃𝑂4 + 3𝐻2𝑂. Phosphoric acid is readily available from a number of commercial suppliers
Let the paste sit for 15 minutes before wiping it away with a damp cloth. If the stain is still visible, try scrubbing it with a nylon brush or non-abrasive sponge. Finally, rinse the area well and dry it with a soft cloth. For tougher burnt stains, you may need to use a commercial stainless steel cleaner or polish.