That is a very good question that had me researching different forums including the Piano Guild and Steinway Piano's among others.
What I use that works for me that I adopted as "best practice " I have highlighted below.
I would love to hear from Patrick Butler's or others on this forums experience on this topic.
- First, I make sure I blow the dust off the tweeter, Midrange Turbine Head and top of cabinet that nestles the midrange with compressed air.
- After this is done, I use a lambs wool duster to gently go over what I just cleaned and only use in one direction following the lines of the speaker housing and then I proceed to do the sides and front of the cabinet.
This works great without any swirl marks that I could see and I use for general cleaning on a weekly basis.
Recently my wife sprayed air fragrance in the room to get rid of some kitchen odors which ultimately showed up as fine spots on the gloss black surface which would not dust off and when I attempted to wipe gently with a microfiber cloth would smear.
From several of the piano forums people referenced using a clean wet chamois with a drop or two of dishwashing detergent to help clean the surface without leaving any residue or streaking. You wring out the chamois until it is very damp, and then after wiping gently in a straight line I follow up with B&W's microfiber cloth to dry any residual moisture. This has worked like a charm and all spots were gone.
If you use a microfiber cloth on its own dry, even if the surface is clean, you can cause fine hairline scratches in the finish. I have been told even using a microfiber cloth wet could do the same, but a wet or moist chamois will not (skin to win).
Mine looks as good as the day they were delivered and I plan to keep them that way.
Would love to hear from others.