With the improment of laser technology ,the laser cleaners have come to play a greater role in the restoration of our building heritage .
It is widely known that the majority of medieval buildings would have appeared quite differently then to how we see them now, and were finished with coatings of limewash or sometimes colourful paintwork (polychromy)
The Q-switched Nd:YAG laser, most commonly used for stone, works by causing the top layer of dirt to be selectively thermally vapourised, or ablated, from the object's surface – using what is essentially a very short pulse of heat – an action that occurs so swiftly that the dirt is removed before there is significant heating of the stone substrate.
