u/dmk-laser

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Following our previous post on wood cleaning, we have been searching for sample pieces and conducting tests on various types of varnishes and oil-based paints used on wooden furniture. We would now like to share the test results with you.

Equipment Features

This device is the result of six months of R&D by our development team, with targeted optimizations for wood's heat-sensitive nature and tendency for heat accumulation. As a result, single-component and two-component polyurethane and epoxy varnishes – which were previously difficult to remove with lasers – can now be effectively stripped using this wood-specific cleaning machine, without burning or charring the wood. Based on our tests, it covers the majority of wood cleaning scenarios.

For single-component/two-component epoxy varnishes and polyurethane varnishes, the equipment achieves effective and rapid cleaning results. Single-component epoxy/polyurethane varnishes are relatively easy to clean, with an efficiency approximately 1.5 times that of conventional Gaussian-beam lasers. Two-component epoxy/polyurethane varnishes, however, could not be effectively removed by conventional Gaussian-beam lasers. This is because after curing with a hardener, two-component epoxy/polyurethane varnishes form a hard, wear-resistant film. Combined with the inherently high roughness of wood, the adhesion of two-component varnishes is extremely strong. Moreover, the transparent surface of the varnish has low laser absorptivity, and forcing removal would only cause thermal accumulation and scorch the wood. Our redesigned wood-specific cleaning machine, through optimized beam quality, pulse control, and scanning trajectory, achieves lower thermal effects, reduced heat accumulation, and stronger removal capability, thereby effectively stripping two-component varnishes.

Key Considerations During Varnish Cleaning

Confirm whether the substrate is solid wood or plywood. Generally, solid wood is easier to clean than plywood. Many plywood adhesives are themselves resin-based glues, which bond particularly strongly with epoxy varnishes, making removal difficult. Of course, plywood is typically of lower value and less frequently subjected to laser maintenance or cleaning in practice, but it is important to distinguish the substrate before cleaning.

Pay attention to wood density. Generally, higher-density woods are easier to clean because their compact lignin structure and fewer hollow spaces result in slower heat accumulation and a relatively higher thermal damage threshold. For example, rosewood, ebony, teak, and oak are high-density woods and are relatively easy to clean. Conversely, low-density woods have more hollow structures, leading to rapid heat accumulation; even a slightly longer laser dwell time can quickly scorch the wood. Extra caution is required when cleaning surfaces made of pine, fir, or paulownia – it is advisable to reduce cleaning power and increase scanning speed to prevent the wood surface from rapidly reaching its damage threshold.

Final Thoughts

Laser cleaning of wood represents a highly promising niche. Traditional sanding damages the wood surface, while chemical paint stripping can penetrate into the interior. Laser cleaning, by contrast, is a non-contact, chemical-free method that is relatively fast and produces no pollution. It offers tremendous market potential and technical advantages for cultural relic restoration, residential renovation, and furniture refurbishment.

By fine-tuning the optical path, improving beam quality, and refining scanning patterns, we’ve made wood cleaning easier and more effective than ever. Tests on common coatings – varnish, oil-based paint, and water-based paint – show results far superior to traditional Gaussian beam equipment. What’s more, our unit achieves about 1.5× the cleaning efficiency of conventional laser cleaners with the same power.

But with so many wood types and finishes out there, we can’t source them all ourselves – and that’s where you come in. We challenge you: send us any wood samples that have defeated your previous laser attempts. No restrictions on wood type or surface contaminants. Our engineers will test them and send you a video of the results.

Everyone who submits a sample gets a gift or a generous discount coupon for DMK’s new wood laser! The campaign runs from July 31 to August 31 – don’t miss out. Join the challenge today!

A robot scans the mold's position to automatically generate a cleaning path; consequently, the workpiece can be placed arbitrarily, eliminating the need for manual programming or manual cleaning.

Handheld pulsed laser cleaning, automated laser cleaning, and handheld continuous-wave laser cleaning equipment were used, respectively.

Carbon fiber reinforced polymer (CFRP) composites, owing to their excellent properties such as lightweight, high strength, and corrosion resistance, have become critical materials in high end equipment manufacturing sectors including aerospace, new energy vehicles, and wind power. During their fabrication, maintenance, and recycling processes, the removal of surface paint coatings is an important and challenging procedure. Traditional paint removal methods, such as mechanical grinding and chemical solvents, tend to cause fiber tearing, resin melting, or damage to the matrix structure, which not only compromises component service life but also reduces the reusability of the material. Laser cleaning technology, with its advantages of non-contact operation, high precision, and environmental friendliness, is progressively emerging as the mainstream solution in this field. By adjusting the energy parameters, laser cleaning enables efficient paint stripping while maximally preserving the integrity of the carbon fiber weave structure and the resin matrix, making it particularly suitable for precision maintenance and remanufacturing of high-value components.

To verify the practical effectiveness of laser cleaning, we conducted tests using both handheld and automated equipment. With a 1000 W handheld cleaning system, the laser parameters and focal distance were adjusted to perform continuous cleaning on the surface of CFRP panels until the grey paint layer was completely removed, revealing the underlying black woven layer. Magnified observation of the cleaned surface showed minimal damage to the carbon fiber weave, meeting the requirements for recycling and reuse. In the automated cleaning tests, a 1000 W water-cooled pulsed laser cleaner was employed, which is equipped with a high-performance custom scanning galvanometer that ensures high processing accuracy and speed, enabling precise completion of predefined cleaning and marking patterns. The system also incorporates a high-peak-power pulsed fiber laser, further enhancing paint removal efficiency. Experimental results indicated that the cleaned area exhibited a clean and neat black woven layer, demonstrating that the laser precisely controlled both removal thickness and range. Under magnification, only a very small number of fibers were observed to be detached, while the weave structure remained intact with no color change. This confirms that laser cleaning induces negligible damage to the carbon fiber substrate, effectively removing the surface paint while preserving the structural and functional integrity of the base material.

It is evident that the key to paint removal from CFRP panels lies not merely in stripping the paint, but in doing so while avoiding damage to the woven structure. Although high-power lasers facilitate rapid paint removal, they are prone to damaging the carbon filaments and degrading the surface performance of the composite panel. Therefore, it is essential to select an appropriate laser source and precisely control the processing parameters to ensure high-efficiency paint removal without compromising the surface structure. Laser cleaning technology offers an efficient and precise solution for carbon fiber components, enabling thorough paint layer removal while maintaining zero damage to the substrate, thereby significantly enhancing the material’s potential for reuse. In the future, this technology is expected to play a critical role in a broader range of applications and to drive the green upgrade of related industries.

In practical shipyard applications, traditional sandblasting, acid pickling, or manual grinding not only pose dust and waste-liquid disposal challenges but also tend to cause scratches or microstructural changes on the surface of shipbuilding steels such as EH36 and AH36, which can compromise the durability of subsequent anti-corrosion coatings. Our team has long been engaged in specialized experiments on laser cleaning for marine steels, and we would like to share some of our process insights for peer discussion.

Laser rust removal requires a balance between effectively removing the rust layer and avoiding damage to the substrate. The optimal energy density and scanning speed vary depending on the rust condition and steel grade. Through a series of comparative tests, we found that for a typical EH36 steel plate surface, an energy density of approximately 2.546 J/cm² and a scanning speed of 3000 mm/s yield satisfactory cleaning results. Electrochemical test data under these parameters (refer to Laser & Optoelectronics Progress, 2023, 60(5): 0514011) show a reduction in corrosion current density of about 57% compared to the original material. This serves as a useful reference for flat-surface cleaning, though in practice the parameters should be fine-tuned according to rust-layer thickness and surface contamination level.

The surface morphology and rust product composition differ significantly between flat hull plates and weld seams, so a single parameter set is unsuitable. We have established dedicated process databases for each: flat surfaces use the parameters mentioned above, whereas weld seams, which involve slag and more severe corrosion, require moderately higher energy density and adjusted scanning speed, depending on weld width, penetration depth, and base metal grade. After multiple rounds of sample testing, the optimized weld process effectively removes slag and rust, with corrosion current improved by an order of magnitude relative to the original weld; however, an exact percentage is not provided because it varies with operating conditions. In addition, weld zones of AH36 steel typically retain residual tensile stress after welding, which can exacerbate stress corrosion cracking in seawater environments. We have observed that properly selected laser cleaning parameters not only remove rust but also induce thermal effects on the surface layer, altering the residual stress state. Under specific energy-density and scanning-speed combinations, the residual tensile stress on the weld surface can be converted into compressive stress, which benefits the structural resistance to stress corrosion. The exact parameters need to be matched to the actual weld condition, and we are continuing to accumulate data on this topic.

Shipyard environments are humid and dusty, placing high demands on long-term laser stability. Our equipment is equipped with a temperature-stabilized fiber laser, a real-time power closed-loop feedback system, and a sealed negative-pressure dust extraction structure, supporting extended continuous operation. The optical path and motion mechanisms have been specifically protected for marine conditions. Prior to delivery, each unit undergoes optical simulation, surface roughness, and electrochemical corrosion testing to ensure consistent cleaning quality. In typical shipyard settings, the equipment has operated continuously over multiple days with power attenuation and beam-spot variation remaining within acceptable limits, and cleaning performance remains stable.

The above process conclusions are based on mechanistic studies of marine steel corrosion and extensive testing on actual ship plates. However, due to the complexity of real-world conditions, we recommend that users conduct final validation using on-site sample plates before large-scale application. We have compiled mature process parameters into a switchable process library covering mainstream marine steel grades, accompanied by standardized operating instructions. This process produces no chemical waste or dust emissions and causes no mechanical damage to the base metal, which helps extend coating service life. By sharing these measured data and process logic, we hope to provide a reference technical pathway for peers in shipbuilding and contribute to the engineering implementation of green repair and construction processes. We welcome discussions on specific working conditions and look forward to jointly refining the process solutions.

A recent real‑world case may offer some insight. Yesterday, three of our trainees from Mexico completed a three‑day training programme, progressing from no prior experience to being able to independently handle common fault repairs, and they successfully graduated. For most non‑practitioners, laser equipment is indeed complex, precise and seemingly "fragile" industrial hardware, which can be intimidating. However, from our teaching practice, we have found that with systematic theoretical instruction and extensive hands‑on practice, most people with basic knowledge of electronics and optics can acquire these skills in a relatively short time. As they encounter more repair cases, their technical proficiency continues to improve, and the more experience they gain, the better they become at solving real‑world problems.

The global laser equipment industry is currently experiencing rapid growth. In 2025, the global laser technology market reached US$24 billion, and in that same year, global shipments of laser processing equipment amounted to 2.17 million units, with the installed base worldwide already exceeding ten million units. Most major manufacturers offer a standard warranty period of just one to two years, and these warranties typically do not cover various types of consumable parts. This means that a large number of equipment units, once out of warranty, will require repair, maintenance and spare‑parts replacement services from the after‑market.

From a cost‑benefit perspective, repairing a laser is often a more economical option than replacing the entire machine. The full lifecycle of a laser system is generally five to ten years, while the core laser source itself can last over 100,000 hours. The majority of failures are localised to optical modules, electrical modules, or the fiber‑coupled QBH connector. The cost to fix these issues typically ranges from a few hundred to a few thousand US dollars, compared with tens of thousands of dollars or more for a complete replacement. For equipment owners, repairing the unit after the warranty expires is an effective way to control operating costs.

In contrast to the ever‑growing installed base, the total number of professional laser repair technicians worldwide is estimated at fewer than 100,000 people, creating a significant gap between service demand and available talent. Our company is a Chinese manufacturer of laser equipment, producing laser cleaning machines, laser welding machines, laser cutting machines and laser marking machines. We have served more than 10,000 customers and export to many countries and regions. The more equipment we export, the greater the after‑sales service pressure – failures caused by improper operation, transportation damage, natural wear and tear continue to occur regularly. Cross‑border technical support involves considerable time and financial costs.

Given this situation, we have gradually developed training programmes in laser repair, with two primary considerations: first, to build more efficient localised service capabilities in overseas markets, allowing us to respond to customer needs more quickly; and second, to provide an entry‑point and upskilling pathway for technicians interested in entering this field.

To support our trainees after their training, we leverage our own supply‑chain resources to provide a full range of spare parts and consumables needed for repairs, including optical modules, control boards, fiber‑coupled QBH connectors, electrical modules, and other commonly replaced components. These parts come from original manufacturers and from qualified alternative suppliers, with assured quality and transparent pricing. In addition, our customer network, spanning multiple countries and regions, generates a steady stream of equipment‑repair requests. We refer these service leads to our trainees based on their geographic location, so that after completing the course they can quickly begin taking on actual repair work.

To date, we have run 32 sessions of our laser repair course, training more than 50 participants from over 20 countries, many of whom are now actively providing repair services in their respective regions. Based on actual feedback, the barrier to entry for laser repair is not as high as commonly assumed – the key lies in having a structured learning path, ample hands‑on practice, and reliable access to parts and business opportunities. We continue to refine our curriculum and support system, with the aim of helping to cultivate more qualified technicians for the industry.

Laser texturing cleaning technology utilizes a high-energy laser beam focused onto the workpiece surface. Through the combined effects of rapid photo-vibration, vaporization, decomposition, and plasma stripping, contaminants are removed from the substrate, achieving a clean workpiece surface. Building on this, laser texturing employs controlled pulsed laser scanning on the clean metal substrate, causing localized surface metal micro-zones to melt and rapidly cool, forming micrometer-scale concave-convex microstructures with adjustable roughness values. This process requires no abrasives, solvents, or chemicals.

Compared with traditional sandblasting, laser texturing cleaning offers comprehensive advantages:

Green and environmentally friendly, with zero pollutant emissions. The laser texturing cleaning process requires no chemical agents, and the waste generated is solid, non-hazardous powder, fundamentally solving the environmental pollution issues associated with traditional sandblasting rust removal. Conventional sandblasting produces approximately 2.5 kg of waste residue per square meter, whereas laser cleaning generates almost no waste residue.

Non-contact processing, with no substrate damage. Laser cleaning is a non-contact processing method, eliminating concerns about workpiece damage or deformation. Unlike the physical impact of sandblasting, laser technology enables precise energy control, achieving "contaminant removal without substrate damage."

Precisely controllable roughness, significantly improved coating adhesion. Laser texturing technology allows precise control over surface roughness and micro-morphology by adjusting parameters such as laser power, scanning speed, and defocusing distance to meet different process requirements. The roughness Ra value can be precisely regulated within the range of 0.1–10 μm with an error margin of ±5%. Coating adhesion can be improved by 200%–300%. Studies have shown that laser texturing can generate regular micro-morphologies on metal surfaces; at equivalent roughness levels, its floating roller peel strength and shear strength in adhesive bonding are significantly higher than those of sandblasted surfaces.

Significantly improved efficiency and lower overall cost. Taking single-roll texturing as an example, laser texturing takes less than 2 hours, whereas sandblasting requires 10 hours—an efficiency improvement of 500%. Although the initial investment for a laser cleaning system is relatively high, it offers long-term stable operation, easy integration into production lines, low operating costs, high speed, and high efficiency, ensuring a rapid return on investment. The comprehensive cost of laser cleaning has already dropped from RMB 12–15/m² in 2018 to RMB 6–8/m² in 2023.

Last week, our engineering team tested the texturing cleaning performance of different power levels and different laser source types. The specific test results are now published below.

His name was "Million"; a colleague rescued him from beside a trash can. His mother had abandoned him, and as a tiny kitten, he was filthy and unsteady on his feet. Our boss, moved by his pitiful state, decided to take him in. Since our company’s quarterly sales target was one million, we named him "Million." With our devoted care, he grew increasingly adorable; we bought him a bed and a cage, and even a GPS tracker to keep him from getting lost. As he grew, he became quite mischievous—his favorite pastime was sticking his head into our water cups, so washing our cups became the first thing we did every morning. We eventually had him neutered and bathed, and our team grew accustomed to his presence. Although he could be a handful—often lying across our keyboards and making it impossible to work—we adored him; whenever we were tired from work, we could pet or play with him. Then, one day, we arrived at work and couldn't find him anywhere. Security footage revealed he had jumped out the window and run off; the tracker’s signal vanished beneath an elevated highway in the city. We searched the area, but aside from traces of blood on the ground, we found no sign of him, and the tracker remained silent. It was a devastating blow; a dark cloud seemed to hang over the entire company. We couldn't bear the sudden loss of the kitten we had raised and cared for so lovingly, and we grieved for a long time. He was truly cute and well-behaved, and our clients loved him too. He would keep us company while we worked overtime or repaired equipment, and he would even climb into display cabinets to act as our model—yet we had truly lost him forever. Later, a colleague suggested adopting another kitten, but we all objected because we didn't want to experience the pain of loss again. It's really wicked. Why did it appear and then leave? Why did it sneak away? Why did it go to "Cat Planet" after we liked it?

Regarding the scan line width of laser cleaning machines, many users mistakenly believe that a wider line width equates to higher cleaning efficiency and capability. This perception is inaccurate. Scan line width refers to the width of the single path traced by the laser spot on the focal plane as the galvanometer oscillates; it determines the coverage area of ​​a single cleaning pass. However, line width is not directly proportional to overall cleaning efficiency—much like an athlete running the same total distance on a 50-meter versus a 100-meter track; the time taken differs little. In other words, whether the line width is 100 mm or 300 mm, the total time required to clean a specific area will not be significantly reduced simply by increasing the line width.

So, how is the line width adjusted? There are two primary methods: replacing the f-theta lens with one of a different focal length, or adjusting the deflection angle of the galvanometer. The core formula is D = 2f × tanθ (where D is the scan width, f is the focal length of the f-theta lens, and θ is the galvanometer deflection angle). When the deflection angle is fixed, a longer focal length results in a wider line; when the lens is fixed, a larger deflection angle also results in a wider line. However, these two methods impact cleaning results very differently. Using a lens with a longer focal length allows for a greater working distance—beneficial for large-format, 3D, and automated processing scenarios—while reducing dust contamination and collision risks. Yet, an excessively long focal length increases the distance the laser travels through the air, leading to energy loss, spot enlargement, and reduced energy density; edge distortion may even occur, ultimately resulting in uneven cleaning or an inability to effectively remove contaminants. Conversely, widening the line by increasing the galvanometer deflection angle introduces serious issues such as heightened stress on the rotation axis, an increased risk of fatigue fracture, edge defocusing, and beam spillage beyond the mirror surface; therefore, this approach is not recommended in practice.

Ultimately, laser cleaning capability depends on laser energy density: if it is too high, the substrate may be damaged; if too low, cleaning will be incomplete. The selection of focal length and line width must prioritize optimal energy density rather than blindly pursuing a wider scan range. Users may notice that devices with identical specifications—such as power output and f-theta lens focal length—list different nominal line widths. These discrepancies often stem from manufacturer adjustments to galvanometer deflection limits, safety margins set by engineers for novice users, or variations in collimator size optimization. Such numerical differences do not directly reflect the equipment's actual cleaning performance.

Therefore, the most reliable way to evaluate a laser cleaning machine is to conduct a side-by-side comparison using identical workpieces and power settings, directly assessing efficiency and results, rather than focusing solely on the scan line width parameter. A high-quality machine represents a comprehensive system solution encompassing laser output, beam shaping, cooling, and airflow protection; every parameter is the result of countless combination tests. By choosing products from a professional team and trusting in their process-wide optimization, you ensure access to a truly efficient and stable cleaning tool.

Our founder, Jally, has produced a dedicated video explaining the principles of line width, the factors influencing it, and its impact on cleaning results. We invite you to watch it on our YouTube channel. Thank you.

It is so unique and adorable, and its smile is one of a kind