I have posted extensively on the “other site“ about this. Some of the chains that I receive to sharpen are so gunked up that I can barely recognize them, let alone see any damage, rust, etc. this may not apply to regularly used, well cared for chains.
I start with a soak in a commercially available, water based decreaser *that contains sodium hydroxide (lye)*. The sodium hydroxide makes a BIG difference. Usually dilute 50/50 with water, and let the chain soak maybe five minutes.
Soaking helps to remove any crud from between the tie straps, drive links, around the rivets, etc., that just running the chain in “clean wood “does not do. It lets me inspect the chain for any damage, cracks, rust, etc., that I would not normally see.
I rinse the chain in water, place it on an old, plastic, cutting board in the laundry tub, and brush / scrub it with an old toothbrush to remove any remaining crud. Some chains require a second soak. If there is light rust, I use a fine, stainless steel ‘toothbrush’ (tig welding scratch brush), or other rust removal methods.
Rinse, then blow off with compressed air, or place in a 150°F oven for about 20 minutes, on an old baking sheet, if I have a bunch to do. This ensures that I get the water out from between the links, rivets, etc.
After sharpening I spray the chain down with WD-40 in an old baking pan, that is lined with paper towels to absorb the extra lubricant.The WD-40 displaces any moisture, penetrates around the rivets, and allows the thicker bar and chain oil to flow there.
Philbert