The best thing is to keep the piano so clean that it requires little cleaning. Of course this cannot be avoided completely. Important for all those who buy a used piano - before it comes into the house, it should be professionally thoroughly cleaned, because over the decades the piano's interior has become contaminated with impurities (e.g. lead oxide, mercury in pianolas, mould, etc.), some of which are considerable and potentially harmful to health.
A new or professionally cleaned piano only needs normal cleaning, just like any other furniture. So a feather duster and lint-free cloth - no cleaning agents, no wet rags. Polished surfaces remain beautiful for a long time when carefully cleaned of dust. If there are scratches or stubborn dirt, it can be polished up properly. However, this requires knowledge of the respective surface and polishing possibilities. Especially the natural shellac of old pianos must not be treated with cleaning agents, polishes or lacquers.
The interior of a piano or grand piano is very sensitive. Please do not clean it yourself, but get a professional and either have it done or have it shown to you. Under no circumstances use a vacuum cleaner or similar in a piano in the sensitive areas - and these are almost everywhere - and work on them.
The soundboard of grand pianos dusts over time. A soundboard cleaning rod set (available here from us), a special attachment for a vacuum cleaner and, if necessary, carefully applied compressed air (do not use in the living room) can help here. But be careful, there are quickly scratches in the soundboard or on the frame.
A soiled and discoloured ivory keyboard can be professionally cleaned, bleached and polished so that it looks uniform and beautiful again. A piano should be kept closed when not in use for a longer period of time to keep dust etc. away from the interior. The piano gets enough ventilation, because all lids are designed in such a way that air can circulate even when the lids are closed.
As tempting as that is, please never place glasses or vases with water in them on the piano or grand piano. The same applies to cups with hot drinks in them. The veneered wooden surfaces react sensitively - especially the old shellac surfaces. Temperature-related condensation water forms on the undersides, causing rims to form. Hot cups dissolve the lacquer and leave edges. Scratches can occur on any kind of object. Such surface damage can only be repaired with great effort. And, if liquid does run into the instrument, potentially great damage is caused.