Rinse, finishes,
This was touched on...
In another life we didn't have ultra sonic cleaners per se' there were sonic cleaners used for somthing else. At the time we used a white coated sauce pan ( yes that white with red trim gammaw has) and Tide ( tm) detergent, we had a 'steam cleaner" that resembles a mini whiskey still.
We needed to cut soap/grease and grime. Any other type of material of saucepan would permantly discolor the metals, Tide at that time was the only laundry soap that would work...others turned the metals black ( a reaction).
Fast Forward
Ultrasonic cleaners came out ( finally and affordable) and we bought 28% ammonia and diluted it ( about a shot glass to 1/2 gal). We need to remove the soap/grease/grime, ammonia cuts this and rinses off the metals we used. We also became high-tech with electric steam cleaners ( old ones still work better). Now after a bit we used various soaps and stuff because ammonia is not GOOD for a lot of metals...NICKEL for one...it will seep into cracks and the nickel will flake from the base metal. Not good.
I used Simple Green, it worked with the metals I used, but the metals I used would not rust [gold ,platinum], and I could rinse clean with a steam cleaner.
So a buddy said lets use the Simple Green and the Ultra Sonic and using a gun ( and no I will not give the name) lets clean and rinse as the public does and see what happens. Yep it will corrode, rust will occur, and the aluminum gets funky. Now I like SG, But we did the same deal with regular dishwashing soap ( Ivory if you must know) , toothbrushed, ultra sonic,steam cleaned and air compressor ( same as before with exact duplicate of firearm) we didn't have a problem. Old boy had money, access to have guns fixed by factory ( little T&E you might say).
There is no holy grail. dunno, Sometimes when something sounds to good - it is.