Surface cleaning (conservation)

Surface cleaning, in Turkish yüzey temizliği, is the removal of dirt, soot, crusts, salts, moss, lichen and later paint layers that build up on the stone, brick, plaster, timber, metal or decorative surfaces of a historic building and damage the material. It is one of the most visible tasks in restoration, but its main purpose is not to make the building look new; it is to remove the agents that cause decay. The natural surface layer that forms over time and protects the material, the patina, is a value to be kept.

Cleaning methods

• Dry methods: soft brushes, spatulas and air to lift dust and loose dirt.
• Water-based cleaning: low-pressure water, steam or fine water mist to soften and remove dirt.
• Poultices: an absorbent layer applied to the surface to draw out dirt or salts.
• Chemical and biocide treatments: for specific soiling and biological growth, using products tested for compatibility with the material.
• Micro-abrasion and laser: applied by experienced specialists, under control and over limited areas.

Principles in practice

Cleaning starts with the gentlest method and moves on only if necessary. Each method is first tried on small, inconspicuous test areas and the results are photographed. Sandblasting, high-pressure water and acidic products erode stone surfaces, increase porosity and accelerate decay, and should be avoided on historic buildings. Because it adds nothing, cleaning cannot be undone: a surface once removed never comes back. Orthophotos taken before and after cleaning are a valuable record for documentation and for post-restoration visualization.