Soot deposits form a bigger problem than is often thought. The facades of houses in an urban environment are often the victim of it, just like statues and other works of art. Infrastructural structures such as bridges, can also suffer from soot deposits.
Soot can also form a big problem on technical installations and structures in an industrial environment where combustion takes place. Places where there was a real fire are often totally blackenend, just like all objects that were nearby the fire. Something else are the components of combustion systems and parts of combustion engines that can be totally black from the soot.
Removing soot is often done by the use of chemical products. This technique isn’t always as effective and is also harmful to people and the environment. This is also usually a manual process that requires a lot of scrubbing and thus is very time consuming.
Laser cleaning is a fantastic technology to remove soot. Soot meets the requirements of laser cleaning perfectly: a thin, black layer. The color black has the property that it doesn’t reflect much light but absorbs almost everything instead. This is just what we want with laser cleaning: Soot absorbs the short, energetic light pulses, causing the soot to undergo a short but very strong temperature rise. This will be so strong that the ablation temperature is reached and as a result, the soot will evaporate. What remains is a perfectly clean surface with a little dust here and there that you can easily blow away.
For the surface, we look at almost all sorts of materials that are able to withstand temperatures of 100°C and more. The real heating happens in the soot itself and not in the underlying material, but the heat from the evaporated soot still radiates a little bit on the surface, that’s why we have certain requirements for the materials.
This brings us to the following surfaces that are suitable for the removal of soot, even if the soot has been on there for a long time: