In short: The laser cleans historic monuments without contact. A pulse of light removes soot, black crusts and later layers of paint, and its power is set so that it stops at the original surface. That is why it works where sandblasting and chemicals would destroy what is most valuable in a monument: the brick face, stone detail, historic joinery and wall paintings. On a building listed in the register of historic monuments, the work requires a permit from the regional monument conservator, and the scope of cleaning is set on the basis of trials on a small area.
Why choose a laser for historic monuments rather than sandblasting or chemicals?
The most valuable thing in a monument is its original surface, and the laser removes dirt without taking even a fragment of it. Popular methods are different.
Sandblasting removes the dirt together with the top layer of the material. On brick it wears away the hard, fired face, on stone it rounds off the detail, on wood it flattens the profiles. Chemicals soak into the pores, need rinsing and neutralising, and on a wall they can come back months later as white salt efflorescence. Pressure washing drives moisture into porous stone, which in winter bursts it from the inside.
The laser works dry and does not touch the surface. The dirt absorbs the beam’s energy differently from the material underneath, so it can be removed layer by layer and stopped at any moment. If the conservator wants to keep the patina, the natural layer the object has gained over time, the cleaning stops right there.
With a historic monument, a mistake cannot be undone. That is why the scope of cleaning and the trials are always set by the conservator in charge of the work.
What can be laser-cleaned in a historic building?
Most of the materials historic monuments are built from can be laser-cleaned, provided that trials on a small area confirm the material tolerates it well. Most often these are:
- Brick and stone facades: soot, atmospheric deposits, graffiti, remains of paint and plaster.
- Sandstone and limestone detail: black gypsum crusts on cornices, portals, sculptures and gravestones. More about stone itself: here.
- Historic joinery: doors, windows, wall panelling, stairs and roof trusses under later layers of paint. What it looks like with wood: here.
- Wall paintings and polychromy: deposits and dirt on the paint layer, always under a conservator’s supervision.
- Metal elements: railings, fittings, crosses and fences with rust and old coatings.
Is the conservator’s consent needed to clean a historic monument?
Yes, if the building is listed in the register of historic monuments. Under Article 36(1)(1) of the Polish Act on the Protection and Care of Historic Monuments, conservation, restoration and construction work on such a building requires a permit from the regional monument conservator (National Heritage Institute). The permit is applied for by the person with legal title to the monument, for example the owner or manager.
If you do not know whether the building is in the register, ask at the regional monument protection office before ordering any cleaning. It saves nerves and money.
We do not replace the conservator. The scope and method of cleaning are set by the conservator in charge of the work. We come on site as the laser cleaning contractor, with our own equipment and qualifications: a laser safety officer certificate, qualifications for working at height and health and safety training. We work according to the conservator’s decisions, often as a subcontractor to a conservation or restoration company that runs the whole contract. What this cooperation looks like: here.
What does laser cleaning of a historic monument look like step by step?
We always start with trials on a small area, and only then clean the whole. The whole process looks like this:
- Assessment. We look at photos of the building and ask about its status: whether it is in the register, who provides conservation supervision and what has already been agreed in the work programme.
- Trials on a small area. On small test panels we clean the surface to different degrees. The conservator assesses them and chooses the level of cleaning, for example keeping the patina or not.
- Choice of parameters. On historic monuments we work with 300-1000 W pulsed lasers designed for precision and conservation work. We set the pulse power and frequency for the specific material and type of dirt.
- Cleaning in stages. We remove the build-up layer by layer and check the result as we go. There is no need to dismantle anything, and the dust from the removed coating is collected by extraction, so we can also work indoors, for example in churches.
- Handover. We check the result together with the conservator. The surface is ready for further conservation work.
More projects: here.
When is the laser not the best choice for a historic monument?
On a historic monument, the method is decided by the conservator on the basis of trials, not by the contractor. If the trials show that the laser does not give the expected result on a given material, we say so openly and do not push it.
It is also worth knowing that the laser is not the fastest method. On large, smooth surfaces with no historic value, other methods will be faster and cheaper. The laser makes sense where the material underneath matters more than the pace of work, and with historic monuments that is almost always the case.
Frequently asked questions
Won’t the laser damage historic brick or stone?
No, if the parameters are matched to the material, and that is exactly why trials on a small area are done. The method is contact-free and dry, so it does not abrade the surface or introduce moisture into it.
Can the patina be preserved?
Yes. The level of cleaning is set by the conservator on the test panels, and the laser can stop cleaning at the chosen layer.
Do you clean interiors, for example churches?
Yes. We use no water or abrasive, and the dust is collected by extraction, so we can work inside the building, even with the furnishings still in place.
How much does laser cleaning of a historic monument cost?
We charge an hourly rate, and give a specific quote after the trials, because only then is it clear how long a square metre of surface will take. More on what the price depends on: here.
Do you work as a subcontractor for conservation companies?
Yes. The conservation or restoration company runs the contract and the contact with the investor, and we carry out the laser cleaning scope according to the conservator’s decisions.
Planning work on a historic monument?
Send photos of the building to biuro@omme.pl and tell us whether it is listed and who provides conservation supervision. We will tell you whether the laser makes sense here and arrange trials on a small area. You can also call: +48 570 471 653. We work across Poland, most often in Greater Poland and Kuyavia, and travel within the EU on request.
Or simply click here to get in touch with us.
