The handpan has a definite advantage over other musical instruments. It is not necessary to tune it before playing. This is a real positive point if you don't have musical knowledge, which makes this instrument accessible to most people. However, it is important to know that a handpan can go out of tune over time and it will be necessary to listen carefully to correct a possible mistuning.
A handpan consists of two steel plates, which can be raw, nitrided or stainless steel, shaped into a dome on which 8 to 14 notes (or more) are hammered to create a musical scale.
Each of the notes is meticulously worked through mechanical and/or manual hammering of the inner and outer surfaces of the notes. Each note consists of a fundamental and two harmonics (octave and counter fifth). All the notes must be tuned in such a way as to obtain a perfectly balanced instrument. It is the 3 dimensional structure of the note that gives its tuning to a handpan note. The GU note and the frequencies around the DING must also be tuned.
An impact on the surface of the instrument can deform the sheet metal and change the frequency of one or more notes of the instrument. As a result, the fundamental note or the harmonics of a note may be out of tune following an impact.
It is in case of accident that a handpan is most likely to go out of tune. If you drop your handpan on the floor or if something hits the instrument, it may go out of tune.
Yes, the way we play can damage our instrument. Over time, playing too loudly can take your steel drum out of tune. Of course, the instrument appears to be solid but it remains fragile. It is important to note that some playing techniques can be particularly risky when it comes to tuning your handpan. This is the case of "ding-bending" which consists in modulating the harmonic of the ding
It is possible that your instrument goes out of tune by itself, without any accident and without having played it too loud. Most of the time, this detuning is gradual and almost inaudible. But some handpans go out of tune faster than others.
The principle is the same as when designing the instrument. However, there are some additional aspects that need to be taken into account. The tuner is likely to be working on a handpan that he did not design himself, which makes the task more difficult. For example, one must understand how the metal was originally formed. Whether it is pressed, rolled, hand-bent, hydroformed or turned, in 1 or 1.2 mm, all determine the tuning technique to be used, as each method stretches and relaxes the metal differently depending on where it is being worked. The way the edges or borders of the notes are formed is also a key. So retuning is a technique that requires skill.
The best solution is to go through the manufacturer who built your handpan. They know the material and tuning techniques used to build it. So, if possible, this should be your first choice. Otherwise, if you can't send the handpan to the manufacturer, turn to a handpan tuner near you. Most handpan manufacturers use the same basic techniques, so if a tuner advertises re-tuning services, you can be sure that they will repair your handpan.