Facade contaminations

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Facade contaminations

Efflorescence / White deposits

Mineral contamination, also called efflorescence, is a common problem on many porous mineral surfaces. Efflorescence is recognised as a white haze, often seen on masonry. Especially brickwork is very sensitive to efflorescence. White deposits damage not just the appearance of the brickwork, but can also damage to surface itself. To effectively remove and prevent white deposits it is important to understand what it is and how it forms.

 

Early white deposits

Occurs during or shortly after a façade is built and is caused by water-soluble salts. In case of early white deposits these salts are sodium-, magnesium- or potassium salts. These salts originate from the mortar, where they occur in high concentrations. The clay that is used to make bricks contain only a small concentration of these salts. In the early stages of building, these salts can move throughout the fresh masonry. The porosity of the bricks allows these salts to migrate throughout. When the masonry dries, the salts on the surface will crystallize leaving the characteristic white deposits. The formation of early white deposits is amplified if the masonry comes in contact with rainwater, because this allows even more salts to move throughout the masonry.

Early white deposits are also called salt-deposits and can be easily removed. In most cases, rinsing with plenty of water can wash away the crystallised salts from the surface. However, as long as there are salts present in the brickwork, the salt-deposits will return. Rinsing salt-deposits away is only a temporary solution and sometimes it can take years for new brickwork to be completely salt-free.

Efflorescence

Efflorescence is the result of a chemical reaction with calcium and results in the formation of calcium deposits. Calcium deposits occur if the ‘carbonation process’ is not fully completed. In this case, free calcium present in the mortar is not fully converted to calcium carbonate resulting in ‘left-over’ calcium in the brickwork. When the brickwork becomes wet by rainwater or ground water the remaining calcium will dissolve and migrate to the surface. Similar to early white deposits, once at the surface, the water evaporated and a white deposit is left. However in the case of calcium deposits, a chemical reaction occurs with the calcium and CO2 from the air. This chemical reaction results in the formation of non-soluble calcium carbonate.

Opposed to salt deposits, calcium deposits are not easily removed. The calcium carbonate is a very hard contamination that can only be removed using suitable cleaners. MAVRO has several suitable removers for removing calcium deposits:

FACADECLEAN, LIMEREMOVER, CEMENTRESIDUEREMOVER.

Interested in the carbonation process?

Cementresidue

Cementresidue is not a form of white deposits or the result of a chemical reaction. Cementresidue is simply mortar that is not removed during construction and is left to cure in the wrong place. Cementresidue can be easily prevented by cleaning spilled mortar while it is still wet. After curing, the mortar is a tough contamination that can only be removed using force or strong chemical products such as CEMENTRESIDUEREMOVER or LIMEREMOVER.

Saltpetre

White deposits found on the bottom of walls with a typical crystalline look could be the result of saltpetre formation. This type of white deposit is caused by rising moisture from the ground. Groundwater can move through masonry by capillary action. Groundwater contains many (organic) compounds such as ammonia salts, calcium, nitrate bacteria, chlorides and sulphates. Especially ammonia and nitrate bacteria are problematic in this case. These compounds can react in the masonry to form potassium nitrate. Potassium nitrate, or saltpetre, then crystallises on the surface and form a white deposit. This type of deposit often occurs on farms where the ground is especially rich in organic compounds.

Atmospheric contamination

Atmospheric contamination is another term for airborne contaminations. This type of contamination occurs almost everywhere and is difficult to prevent. In the long-term, atmospheric contamination can result in a build-up of dirt and other particles.

Atmospheric contamination is caused by particles that float in the air and land on surfaces. The particles remain on the surface and form a grey/black residue.

Atmospheric contaminations can come from natural sources such as salts, plants and animals that. Most atmospheric contamination is from inorganic sources however. Traffic, industry and agriculture are the main source of pollution. Traffic and factories produce tonnes of miniscule particles which end up in the air. These particles end up on buildings and give a dirty and worn look.

Luckily most atmospheric pollution is easily removed using the right products. MAVRO has a dedicated line of products for cleaning buildings and facades:

Green deposits

Green deposits are a collection of algae and moss (lichens). Green deposits can occur on surfaces that remain moist for long periods of time. Another important factor is a lack of direct sunlight. A lack of sunlight prevents moisture in the surface from evaporating and allows green deposits to form easily. It is not unexpected that green deposits often form during winter time. In these periods the sun is low in the sky, and the power of the sun is at its lowest.

Green deposits can occur on almost any surface. Common surfaces include tiles, bricks, wood (garden fencing), concrete tiles, natural stone and roof tiles.

Green deposits are easily removed using a professional algae remover such as ALGEN REMOVER.

Read more about the formation of green deposits and how to prevent it

Graffiti

Graffiti is obviously a very common form of façade contamination. Graffiti comes in many forms and requires a specialist approach to removing and preventing it.

Read more about graffiti and how to remove and prevent it

Facade cladding

Originally buildings and walls were made of concrete, wood and masonry. Nowadays, offices and many other buildings are built using synthetic and composite materials.

A common building material is HPL, or High Pressure Laminate. A well-known brand of HPL is Trespa®. These kind of composite panels are often use for cladding buildings.

HPL-panels are made from wood fibres or paper, combined with a phenolic resin binder. Under high-pressure and high-temperature these materials are compressed into high density panels. The addition of pigments to the top-coat allows them to be manufactured in many different colours. This production process results in panels that have a very ‘closed’ structure, making them very resistant to pollution and weathering. Graffiti can also be removed from these panels relatively easy.

These properties are an obvious reason why this type of panel is often used in the construction of buildings and detailing.

Despite the excellent durability, even HPL-panels must be cleaned and maintained throughout their lifetime.

Weathering of aluminium and plastic (window) frames

A very common problem with buildings is the weathering of paint. All materials used outside are subjected to the environment, however, painted window frames and doors will often show dramatic degradation before anything else. In the case of paint, the first sign of degradation is a loss of shine or gloss. Gloss reduction is often caused by ‘chalking’ of the paint.

UV-radiation from the sun causes the resin/binder in the paint to break down as a result of photochemical reactions. The breakdown of binders will result in pigment particles to loosen and collect on the surface.

It makes sense that satin or matt paints show signs of chalking sooner because they ‘skip’ the first step. High gloss paint also reflect more sunlight, making their outdoor durability even better.

Not every type of paint is vulnerable to UV-radiation, and therefore chalking. This is very dependent on the type of binder that is used. Some binders are very known for their UV-resistance. The colour of the paint also influences the durability. Especially yellow, red and orange tinted paints are more vulnerable to UV-light and will show signs of chalking sooner. This is caused by the nature of the pigments. Colours on this side of the spectrum are often made from organic pigments. These organic pigments are much more vulnerable to UV-radiation than inorganic, or metal pigments.

Generally, a chalked paint has reached the end of its lifetime. One of the ways for restoring the colour is by painting the surfaces again. Painting is often very time-consuming and costly.

MAVRO international has developed a line of ‘renovation coatings’ for this exact purpose. This line of products is called the NITOrange. These coatings were all developed to restore the look and durability of chalked surfaces in a fast and cost-effective way. MAVRO NITOrange is a line of protective and colour/gloss restoring coatings. The products are specially designed for non-porous surfaces such as aluminium and plastic frames, HPL-panels and other painted surfaces.

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