Probably a very silly question, but does ultrasonic cleaning simply expose case colouring that is there under the accumulated crud, or does the process in some way re-activate the colours on the surface layer.
Either way the results are most impressive.
Excellent question. I agree that the ultrasonic cleaning "uncovers" the original colors. I recall a photograph that Oscar Gaddy included in his wonderful two part treatise on cch that showed what the surface of cch steel looks like under an electron microscope. It is an amazing picture showing crystalline shaped forms that comprise the surface. These refract light in such a way as to cause the eye to see the colors. Even though the surface feels very smooth to the touch, those shapes are present, until worn away, at which time the colorful effects are lost. It just stands to reason that years of accumulated dirt and grime can work it's way between those minute, shaped, structures on the surface, causing the light to no longer be refracted, by being blocked.
Actually, the cleaning away of all that grime does constitute a "re-activation" I guess.
