One of the questions we are frequently being asked is what type pf paint should be used for the renovation of old buildings.
There are two main paint categories on the marketplace:
- Emulsion paints: the modern alternative, manufactured from various chemicals
- Mineral paints: the traditional alternative, made of natural materials
Emulsion paints are the most common paint types, the ones you can by at home improvement stores such as B&Q. These are manufactured from synthetic chemicals including resins, solvents (e.g. turpentine), synthetic pigments (e.g. titanium dioxide, zinc oxide) and additives.
Due to their composition these paints are classified as non-breathable. They act like a film. They form a film on the surface that prevents moisture from going in or out. For new buildings this is not a problem as they are fundamentally designed to be waterproof and their building materials have a low moisture content.
Older buildings however are different. Their building fabric is damper and they also have been designed to be water permeable. They get wet and they dry out naturally through evaporation. In this case not letting humidity escape is not good as the accumulation of moisture under the surface can lead to a gradual deterioration of the building fabric.
For this reason, wherever breathability of the building fabric is important, emulsion paints should not be used and mineral paints should be the preferred option.
Emulsion paints for special paints have also been developed, including fire retardant and anti-mould paints which contain fungicides to reduce the growth of mould. This is only a temporary solution as over time the fungicides evaporate making the paint less effective.
Mineral paints are the traditional alternative to chemical emulsion paints. They are manufactured from natural materials: quartz sand (silicates), natural pigments and other minerals. They are long lasting and non-toxic.
Mineral paints create a chemical bond with the wall surface hence they are much more lasting. They are breathable, they allow for the passage of water vapours at molecular level, letting damp walls naturally dry out.