• Contactless and gentle on surfaces: The laser beam removes dirt and deposits without physical abrasion or the use of chemicals. As a result, the original surface of brick or stone remains intact—this technology is significantly milder than sandblasting or brushing, minimizing the risk of damage to architectural details.
  
  
• Precise and selective action: The laser can be accurately directed at a specific section of decoration or facade. Dirt, soot, or corrosion layers absorb the laser’s energy and evaporate (ablation), while the clean underlying material remains untouched. This allows for the removal of only unwanted layers, such as the black crust formed by pollution, without damaging intact brick or the patina of noble metals.
  
  
• Clean and eco-friendly technology: The laser method does not require water, sand, or chemicals—so no harmful runoff or waste is generated that would need disposal. The removed dirt evaporates or settles as dust, which can be easily captured with an industrial vacuum cleaner. Laser cleaning is environmentally friendly and safe for operators, as they are not exposed to chemicals or quartz dust.
  
  
• Effectiveness in difficult cases: The laser successfully removes contaminants that resist other methods. It can eliminate soot, atmospheric deposits, biological coatings, as well as rust from iron or oil and grease from stone and metal surfaces. It is particularly effective in cleaning delicate polychromies, sculptures, and intricately textured elements where traditional methods fail.
  
  
• Speed and efficiency: Thanks to high-energy pulses, the laser removes contaminants very quickly, point by point. Modern high-power lasers can clean up to several dozen square centimeters per minute, depending on the type of contamination. While preparation (ensuring safety, calibration) is essential, the cleaning process itself is often faster than manual methods, especially for intricate details.
  
  
• Lower additional costs: The absence of sand, abrasives, or chemicals means lower operating costs compared to methods like dry ice blasting or sandblasting. While laser equipment requires a significant investment, that burden falls on us as the service provider—our clients only pay for the service performed, saving on equipment costs.
  
  

Applications in historical and sacred buildings

The laser is highly effective in the conservation and restoration of various historical structures, particularly sacred buildings. Here are examples where our service is applicable:

• Brick facades of churches and tenement houses: Years of soot, candle smoke, chimney deposits, and urban pollution cause bricks and stones to darken. Laser cleaning restores the original color of brick facades without risking mortar erosion or damage to the fragile surface of old bricks.
  
  
• Stone sculptures, bas-reliefs, and architectural details: Statues of saints, facade reliefs, and ornaments often accumulate a dark layer of dirt and biological patina. Laser cleaning can selectively remove these deposits, revealing the original bright appearance of the sculpture. A notable example is the laser cleaning of historic statues, such as the Caryatids of the Athenian Acropolis, where the black layer was removed from the marble without affecting the ancient material.
  
  
• Interiors of historic temples: Walls and vaults covered with paintings or bare stone are exposed to soot and dust deposits. Laser cleaning allows for the gentle restoration of stone pillars, decorations, and altar elements without the need for water, which is crucial for interior spaces as it prevents moisture buildup in the walls.
  
  
• Wooden and polychrome elements: Although wood is a delicate material, in certain cases—such as charring after a fire or thick soot layers on carved wood—laser cleaning, when set to appropriate parameters, can remove surface deposits without damaging healthy wood. Similarly, lasers are sometimes used for cleaning valuable paintings and frescoes. While Imago Group primarily focuses on brick and stone, we can collaborate with heritage conservators to tailor the method for such delicate surfaces.
  
  

• Metal architectural details: Historic wrought doors, grilles, bronze monuments, and plaques can accumulate rust or layers of paint and dust. Laser cleaning effectively removes rust from iron and old paint coatings, preparing the surface for new anti-corrosion protection. Importantly, the process is precise enough to clean metal elements in situ, without requiring their removal from the structure.

• Graffiti and coating removal: Unwanted graffiti on historic walls is becoming an increasing problem. Traditional methods, such as chemical removal or sandblasting, can damage the substrate. Laser cleaning offers an alternative—it can vaporize various types of spray paint layer by layer. Dark colors of graffiti, in particular, absorb laser energy well and disappear without leaving a trace on the original brick or stone. However, testing is always necessary to determine the correct laser parameters for the specific type of paint.
  
  

How does laser cleaning technology work?

Laser cleaning is based on the phenomenon of laser ablation—short pulses of high-energy laser light strike the surface of dirt or corrosion and immediately vaporize it (turning it into steam and fine dust). Our equipment emits a laser beam with controlled wavelength, power, and pulse duration, allowing adjustments for different materials: one configuration works for soft brick, another for hard granite, and yet another for oxidized copper surfaces.

We primarily use pulsed lasers with pulse durations in the nanosecond range, as they ensure effective contaminant removal with minimal thermal impact on the substrate. The short pulse vaporizes dirt but does not have enough time to heat the underlying material—maintaining a low substrate temperature, preventing cracks or deformations. The laser beam is precisely guided across the surface using a scanner or manually by an operator, typically cleaning small areas point by point. For larger surfaces, the laser draws a dense grid of points, which collectively clean the entire area.

Key parameters include laser power, single-pulse energy, pulse frequency, and wavelength. For cleaning mineral surfaces (brick, sandstone, plaster), ND:YAG lasers with a wavelength of 1064 nm or 532 nm are often used—this wavelength is well absorbed by dark contaminants (e.g., soot). The power of available devices ranges from several dozen to even 1000 W, but for precise monument conservation, medium-power equipment (e.g., 50–200 W) is typically used, providing better control over the process. Next-generation fiber lasers are highly efficient and durable, which is why Imago Group invests in this type of equipment—they ensure work stability and effective cleaning with relatively low energy consumption.

An important component of the system is safety: our devices are equipped with protective measures, and work is carried out in compliance with occupational health and safety regulations. Operators wear special glasses to protect their eyes from reflected laser light, and the work area is cordoned off during cleaning. We also ensure the extraction of dust generated during the vaporization of contaminants—we use filtration systems to remove fine dust particles and harmful substances (e.g., lead from old paint) from the environment.

Comparison with traditional cleaning methods

Various cleaning methods are used in heritage conservation—each has its applications, but laser technology stands out where precision and gentleness are required. Below is a comparison of laser cleaning with other popular methods:

• Sandblasting (abrasive methods): Stream-abrasive cleaning, such as using sand or microbeads, mechanically removes dirt but also erodes the surface layer of the material. This can dull stone, damage sculpture details, or cause mortar loss in bricks. Additionally, sandblasting generates large amounts of dust and waste, requiring environmental protection. In contrast, laser cleaning does not damage the original surface and does not leave a mess—it works precisely only where needed.

• Chemical cleaning: The use of solvents, detergents, acids, or chemical pastes can dissolve contaminants, but the results are often difficult to fully control. Chemicals may react with the substrate (e.g., acids damaging calcium carbonate in stone) or leave residues in the material’s pores. Additionally, it requires subsequent rinsing with water, increasing the risk of moisture buildup in historical structures. Laser cleaning eliminates the need for chemicals, making it more suitable for preserving heritage materials and environmentally friendly.
  
  
• High-pressure water/steam cleaning: Water-based methods (e.g., hot steam) are relatively gentle and eco-friendly but have limited effectiveness against heavy contaminants (soot, black crust layers). Water can penetrate deep into walls, which may be undesirable for old structures. Laser cleaning is dry—avoiding moisture infiltration into walls, which is important for fragile plasters or surfaces prone to mold growth.
  
  
• Dry ice (sublimation cleaning): A stream of dry ice pellets removes dirt without leaving residue (the ice sublimates), but this method requires expensive equipment and the purchase of the medium itself (CO₂). Laser cleaning also leaves no waste and proves to be more economical for larger projects. Additionally, cleaning with dry ice is less precise—it’s difficult to clean intricate ornaments without treating the entire surface indiscriminately.
  
  
• Manual mechanical cleaning: Scalpels, brushes, and sandpaper—used selectively by conservators—offer control but are extremely time-consuming. Additionally, there is always a risk of scratches. Laser technology speeds up many of these tasks while maintaining (or even exceeding) the precision of a human hand. For example, a large statue can be cleaned in a fraction of the time it would take to scrape away dirt manually.

Summing up, laser cleaning combines the advantages of chemical methods (no mechanical damage) and mechanical methods (no chemicals, dry process), while eliminating many of their downsides. It is currently the most advanced technology for the conservation of historic surfaces and is increasingly recommended by conservators as the preferred method for valuable objects.

Benefits for the investor and heritage custodian

Investors, managers of historic buildings, and conservators gain tangible benefits from the use of laser cleaning:

• Preserving the original substance of the monument: The minimal invasiveness of laser cleaning means that only the necessary elements—dirt, deposits, unwanted old layers—are removed, leaving as much of the original material as possible. As a result, every brick, stone, or sculpture retains its historical authenticity, and the cleaning process does not cause the loss of valuable patina (unless its removal is the intended goal).
  
  
• Aesthetic value and increased attractiveness: A clean, restored church facade or a gleaming figure on a building’s front catches the eye and enhances the object’s visual appeal. For parishes, this means pride among worshippers and greater interest from visitors; for cities, it improves the image of public spaces; and for private investors, it increases property value.
  
  
• Long-term savings: While modern technology may seem expensive, properly executed laser cleaning results in lower conservation costs in the future. The absence of surface damage means there is no need for costly detail reconstruction or filling in losses (which is often necessary after aggressive sandblasting). A laser-cleaned object accumulates dirt more slowly—removing layers of oils and soot can improve the material’s “breathability” and make it harder for contaminants to settle again.
  
  
• Worksite and environmental safety: Properly secured laser cleaning can be carried out without closing the facility for an extended period. There are no chemical splashes or dust clouds escaping beyond the work zone. In churches or city centers, cleaning can be done in sections without significantly disrupting the building’s use. The investor also does not need to worry about hazardous waste disposal costs—practically none are generated.
  
  
• Innovative image and alignment with trends: Using the latest methods demonstrates the professionalism of the facility manager. In the eyes of sponsors or grant providers (e.g., for projects funded by conservation funds), employing laser technology can be an advantage, showing a commitment to the best possible solutions. Additionally, this method aligns with the growing emphasis on ecology and sustainable practices (no chemicals, water conservation).

Overview of laser technologies on the market

To provide the highest level of service, we monitor the laser cleaning technology market and use equipment tailored to conservation needs. Among the available devices, we can distinguish:

• Nanosecond ND:YAG lasers: A classic in heritage conservation—they emit a wavelength of 1064 nm (often with a 532 nm option), in short pulses of approximately 10–20 ns. These devices (e.g., Q-switched ND:YAG used in museums) are excellent for removing black deposits from light-colored stone due to the phenomenon of selective absorption (dark dirt absorbs energy, light-colored stone reflects it).

• Fiber pulsed lasers (fiber laser): Modern constructions with high stability. Available in various power outputs – from portable 20-50 W to large 500+ W units mounted on trolleys. They are characterized by lower maintenance costs (long lifetime of the source) and mobility. An example is the SPYRE SPR500 type device (Czech Republic) – a mobile cleaning laser with a power of 500 W that can operate in the field, or German CleanLaser systems appreciated in industry and conservation.
  
  
• Continuous-wave (CW) and pico/femtosecond lasers: Although less commonly used in standard service offerings, they are worth mentioning. High-power continuous lasers can quickly clean, for example, rusted pipes in industry, but they are usually not used for heritage conservation due to lower control (continuous heating). Meanwhile, ultra-short pico- or femtosecond pulses represent the latest generation, offering even greater precision (allowing layer removal at the atomic level). However, the cost of such devices is currently very high, and they are mainly used for research and exceptionally delicate objects.

Imago Group collaborates with laser equipment suppliers from Europe to provide clients with access to the best solutions. We focus on devices certified for conservation applications, equipped with the necessary safety and effectiveness approvals. When needed, we consult experts (e.g., laser manufacturers or research institutes) to determine optimal settings for unique tasks. This ensures that our service is technologically advanced while remaining safe for the object.