Paulownia soundboards are very soft, so an accidental knock easily leaves a small dent. Never fill the hollow with wood dust mixed into chemical glue — that affects the tone. Instead drip clean water into the dent and let the paulownia absorb it slowly and spring back. If it does not return fully, fill with paulownia dust bound in animal glue, sand smooth and touch in the colour with shellac. Animal glue sets with natural voids inside, so it does not block the transmission of sound. If a small cosmetic flaw does not bother you, it usually needs no repair at all and does no harm to the tone.
Step one: tell a dent from a crack. A dent is a local depression with the grain still continuous and no splits around it. If the lacquer has cracked, the grain is torn, or it clicks when pressed, that is structural damage — do not work on it yourself; contact the maker or a technician.
Step two: watch it for a day or two. Paulownia has some spring of its own, and many shallow dents recover part of their depth within a day or two of the knock. Do not keep pressing or touching it during that time, and do not rush to fill it.
Step three: draw it back with water if needed. Use a cotton bud to place a small amount of clean water in the dent so the wood absorbs it slowly and lifts; do not add too much at once — let it dry and repeat. Never use hot water, a hairdryer, a radiator or direct sun to speed it up: sudden heat and sudden drying are what turn a shallow dent into a crack.
Filling and colouring: only for appearance. If the dent will not come back and really bothers you, fill it with paulownia dust in animal glue, sand it level and touch in the colour. That kind of glue sets with natural voids and does not block vibration. Chemical glue mixed with wood dust sets into a hard lump — effectively embedding a dead spot in the soundboard — and the tone will change.
Most dents that do not affect the tone need no repair. A soundboard vibrates as a whole, and a shallow dent a few millimetres across does not change the sound. Rather than risk a bad repair for the sake of looks, leave it — which is what most experienced technicians will tell you.
If you are unsure how deep the dent is, or the knock landed near a bridge foot, send us a photo and the model and we will tell you whether it needs attention.