Brickwork is composed of red clay bricks held together with the the help of mortar. While bricks are made up of clay, cooked in a kiln, the mortar can be cement, plaster or any other material. A brickwork construction is tricky to deal with because of the variety of constituents. One material which can be used to clean bricks might affect the strength of mortar used in masonry. Likewise, in order to clean the mortar, sheer vigilance is required lest the color or texture of bricks be affected. Therefore, brickwork cleaning becomes a technical procedure- to be performed by specialists and professionals.

Brickwork cleaning is a demanding job because even within a single brick, there can be variety of surface texture, hardness and porosity. Hence, an abrasive material or pressure water jets cannot be used for cleaning brickwork. They can damage bricks because of abrasive activity or water seepage through pores of the brickwork.

Any rigorous cleaning procedure cannot be used for brickwork cleaning. Other than the variety of materials used in brickwork, some bricks have a ‘fire skin’- a thin layer of densely packed particles. During brick cleaning this layer must never be damaged. Also, the soft mortar such as mixture of lime and sand, cannot endure a rigorous procedure. For all these reasons, brickwork cleaning has to be carried out with careful consideration.

Cleaning brickwork with only water cannot clean the structure properly, because it can only remove the easy layer of dirt on the top and stubborn stains will not come off. Using a non-ionic soap will also not help with the cleaning. If the building is cleaned using a brush, its harsh bristles can damage the structure because of their abrasive quality. Even if cleaning process is carried out with utmost care, brushing can deteriorate the quality of historic brickwork. Abrasive cleaning must be avoided under all circumstances, especially for paint removal or graffiti removal on brickwork.

For all the above mentioned reasons, a brickwork structure can only be cleaned through chemical cleaning. It accommodates variations in texture, hardness, porosity, and condition of the bricks. Stubborn stains, paint and graffiti can be removed effectively with the help of chemical cleaning. For thorough cleaning of tough stains, an alkali-based degreasant is used. This is followed by hydrofluoric acid. In case of light soiling, only acidic agent is used. In order to limit cleaning agents’ impact, the brick surfaces are pre-wetted properly. Once the procedure is applied, the surface must be rinsed thoroughly so that the chemicals do not keep performing their activity on brick surface, and start causing damage to the brickwork.

At TW Brick Cleaning Walthamstow, we prefer using thixotropic gel or a poultice as cleaning agents because of their thick viscosity and lesser absorption. When the building is such that dwelling time is longer, clay-based alkaline poultices are preferred. Since lime-based mortars have high absorption capabilities, but they are softer and more porous than the surrounding bricks, cleaning agent has to be chosen wisely by keeping in view few other factors such as the strengths of chemicals, dwell times, water pressures, pre-wet time and so on. This helps in controlling the damage to the mortar.