I remove the chain, place it in a jar of nitro (or other strong degreaser) and shake it. Dirt and abrasion settle at the bottom. Now I hang the chain in the centre over a bowl to dry. Spray with brake cleaner from top to bottom. Once dry, place it in a jar of gear oil (high viscosity). Movement also helps here. This allows the oil to run into all gaps. Then put it back over the pot to drain. Wipe with a cloth, finally with brake cleaner, then with drying spray. Advantage: You can never achieve this quality when the chain is installed. If you have a second chain, you are not under time pressure. Another high-end tip: If you mark the chain before removing it (running direction and top side), then you can switch from the top side to the bottom side with the same running direction, resulting in a new, unworn area.
