The cleaning of facing brick is mostly carried out by means of blasting. Blasting ensures (even with the tricky yellow stone) a nice, smooth and even result. Blasting also makes it possible to carry out completely ecological (sand, air and water) cleaning work under the increasingly strict rules for chemicals. The idea is that the blasting of facades and monuments irrevocably means damage to the stone and the jointing.
Even though cases of this are known, it is quite possible to clean facades and monuments without damage. It is important that you have a blasting system that has a nice even jet at low pressure. In any case, this type of blasting work always requires alertness.
Many houses are blasted with Olivine sand. Olivine sand is a sand grain available in various grain sizes that breaks when it hits the facade. When smashed, kinetic energy is released that ultimately provides the cleaning effect. The advantage of breaking the grain is that the impact is considerably less. Facades should always be cleaned with water addition. The sand grain must first pass through a water film, which also reduces the impact without destroying the cleaning work. With Olivine sand it is quite possible to clean facing brick without damaging the structure of the brick or the protective top layer. Cleaning the jointing is also possible as long as it is not very soft and porous. In that case, the jointing must also be replaced.
Calcium Carbonate, also called lime powder, is a very soft blasting medium. When the grain is softer than the surface, the chance of damaging the surface is considerably less. This has the advantage that it is possible to clean facing brick and vulnerable monuments without damage. This also offers the possibility to clean the organic pollution of old buildings without removing the patina layer (the dark layer that often gives the old character to a building). These blasting media with a water additive are used at all times.