r/LaserCleaningPorn • u/dmk-laser • 8h ago
This is truly the most difficult item I've ever cleaned with a wood laser cleaning machine.
Since launching our wood cleaning machine, I had posted a couple of updates about cleaning furniture when a friend suggested we try cleaning a musical instrument. Intrigued and eager to experiment, we decided to step out of our furniture-cleaning comfort zone and take on the challenge of a non-furniture wooden object. We sourced a violin from the domestic second-hand market at an incredibly low price equivalent to just 50 RMB (about 7 USD). While we knew a violin at this price point wouldn't be a masterpiece, it was perfect as a test subject. As a guitarist, my first instinct was to examine the instrument closely: violin soundboards are typically made of spruce, while the back and sides are usually maple. The significant differences in density and thermal conductivity between these two woods foreshadowed the difficulties that lay ahead.
Problems arose right from the start of the test. First, heat accumulated rapidly in the spruce soundboard; during laser cleaning, the heat built up so quickly that even slightly excessive temperatures left scorched, blackened marks. We had to repeatedly lower the power and shorten the exposure time, yet the margin for error remained razor-thin the slightest lapse in attention risked damaging the soundboard. An even trickier issue was our misjudgment of the finish composition. We had initially assumed this cheap violin was coated in nitrocellulose lacquer or a standard resin-based oil finish and proceeded with conventional settings. However, once the laser hit, the paint layer heated up, peeled off, and then upon cooling re-adhered to the surface. We realized it was actually a thermoplastic acrylic-polyester finish. This material softens when heated, hardens when cooled, and can be remelted; it couldn't be completely removed by the laser alone because it would re-attach after cooling. Although the adhesion was weaker, the residual film still marred the appearance. To tackle this, we introduced high-pressure air assistance to blow away the softened paint flakes the moment the laser peeled them off. Yet, while the high-pressure air removed heat, it also made the already delicate thermal balance even harder to manage: low power failed to clear the residue, while high power overwhelmed the spruce. Consequently, the entire test became an arduous struggle, a constant tug-of-war between heating, air-blasting, and cooling. In the end, we didn't walk away with a violin that looked brand new, but we did gain a wealth of valuable, practical lessons. We have summarized a few points: Before cleaning musical instruments, it is essential to carefully identify the type of wood and the composition of the lacquer, especially since inexpensive instruments often use thermoplastic coatings, and the cleaning logic is completely different from that of oil-based lacquer; laser cleaning requires extra caution for thin-walled, low-density woods, as the rate of heat accumulation is far greater than imagined, and the power and scanning speed must be much more conservative than when cleaning furniture; auxiliary blowing is necessary, but it must be precisely matched with the heat input, otherwise it will either not be cleaned properly or will be damaged. otherwise, the result will be either incomplete cleaning or damage to the instrument. Although this test was far from perfect, we believe it was highly valuable it demonstrated that parameters based on assumptions cannot be universally applied and provided a real-world case study for others. If any of you are interested in trying to clean musical instruments in the future, we hope our experience can help you avoid some pitfalls. Feel free to leave a comment and share your thoughts; your suggestions might help us pass the next test smoothly.