Every second-hand purchase is a matter of trust! But: trust is good - control is better!
In general, there is nothing against buying a used piano; however, the model must of course be in good condition, and this is difficult to judge as a layman.
A good piano dealer will give you a (usually three-year) guarantee that everything is in order, both technically and in terms of content, but it is more difficult to buy a private piano.
Don't trust unchecked statements like: we had the instrument overhauled 10 years ago for a lot of money/ you only have to tune it/ practically nobody played on it/ our piano teacher says it would be a great instrument, etc.)!
An old "sweetheart" from the Internet for little money (or even for free pick-up) is tempting, but we strongly advise against it (especially for beginners!), as these instruments are usually no longer playable or tunable properly. Otherwise one would not give away this piano for little money or for nothing. The real reason for this is mostly that one would like to save the several hundred Euro expensive collection and disposal.
A torn or worn out
soundpost, a tensionless soundboard, a
hairline crack in the casting plate, felts eaten by moths or mice; all this makes a piano unusable and a total loss.
And pianos with an
upper damper mechanism and/or a wooden frame instead of a cast-iron frame belong in the "garbage can" anyway!
So these 60 to 130 year old instruments are no longer usable for the enjoyment of the piano, for the motivation to practice, let alone for specific lessons.
Unfortunately, even piano teachers (if they are not also piano builders by chance) are usually unable to judge whether the instrument is technically in order and will remain so for years to come.
Which used pianos can I buy?
Please make sure that the instrument is at most 50 years old: Since then the
tuning position of the pianos has improved considerably due to the use of
multiplex in the soundpost!
It is best to take a specialist (i.e. a piano builder) with you, he can really judge the condition of the instrument.
It should also be a brand, then even 40 years, if it has been maintained and serviced regularly, are not a problem (e.g.: Bechstein, Blüthner, Bösendorfer, Feurich, Grotrian Steinweg, Hellas, Ibach, Kawai, Pfeiffer, Sauter, Schiedmayer, Schimmel, Seiler, Steingraeber, Steinway, Yamaha).
When is an overhaul of the old piano worthwhile?
A complete overhaul usually costs more than a new brand piano.
This is due to the fact that every piano has tens of thousands of components and that everything has to be dismantled, replaced and reassembled. And it's possible that the accustomed sound character has completely changed, that's hard to predict or influence, the components have also changed.
It's worth it, for example, if it's your old, but familiar and proven instrument, if the cost of an overhaul is manageable or if it's a heirloom or memento of a loved one.
Once again some points roughly summarized:
A good
tuning posture is the most important thing; this means that the
pegs must be firmly seated in the soundpost, otherwise the
piano tuner cannot tune the instrument any more and the instrument becomes unusable.
The
mechanics and the
keyboard must "run" evenly and cleanly, otherwise one cannot play sensibly. There must be no rattling or wobbling; the keys must be evenly spaced and the hammers in "row and file"!
The
hammer heads must not be played, as well as the
damper felts and all other felts of the mechanics, otherwise an even piano playing is not possible.
There must be no rust on any metal parts (
strings,
pegs,
axes,
pilaster strips,
grapples, etc.)!
The
resonating body, especially the soundboard, must not have any cracks or other damages, otherwise the piano will not sound and tones are rattling and undifferentiated.
The
cast plate must be intact and without damage, otherwise a piano will not hold its
tuning and will be unusable.
The
sound quality and the sound character must be pleasant and uniform, otherwise it is simply no fun to sit down at the instrument.
Last but not least, the appearance should be appealing - consider that it is also a piece of furniture!