What is the name of dry paint

Paint against mold: how well does silicate paint work?

With the right wall paint you can prevent mold growth. We explain how paints can work against mold and why silicate paint is particularly suitable for mold prevention.

  1. This is how mineral paints work against mold
  2. Silicate paint or lime paint: which is better against mold?
  3. What are silicate paints?
  4. Alternative colors for mold prevention
  5. Color against mold: there are also limits

Silicate paint is particularly effective against mold. In the following we give you an overview of mineral paints, how paint works against mold and also name the advantages and disadvantages of silicate paint.

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Excessive humidity is the most common cause of mold growth in the home. The room air can only absorb a limited amount of moisture. As a result, water vapor condenses on the cool walls and the resulting water settles there. Above all, wall surfaces that have been painted several times or woodchip wallpaper allow almost no moisture to penetrate. The wall becomes damp - and provides the ideal breeding ground for mold.

Wallpaper or emulsion paints also provide the mold with nutrients because they contain organic components. Gypsum substrates, which are slightly acidic, provide the ideal environment in which mold feels comfortable.

If the walls can absorb moisture from the air when the air humidity is high and later release it back into the room air when the air humidity has decreased, then that is good for the indoor climate. In addition, mold cannot develop so easily. And this is where mineral paints come into play. This means inks with an inorganic or mineral binder. The mineral paints include silicate paint and lime paint.

This is how mineral paints work against mold

Mineral paints have two advantages that make them anti-mold:

  • They are basic: Since molds like acidic environments and basic environments are deadly for all types of mold, they do not grow on mineral paints.
  • They are open to diffusion: This means that they can absorb moisture and also release it again. In this way, no condensation forms on the wall.

However, only pure mineral colors have these properties. There are also emulsion silicate paints or lime paints with linseed oil or casein. These compensate for some of the disadvantages of mineral paints, but these products are somewhat less permeable and can provide food for mold. However, they usually have better mold-inhibiting properties than conventional emulsion paints.

In the technical data sheet for the respective color, you should pay attention to the pH value of the color. The higher the better. Ideally, it should be over 11.
You should also check how open the paint is to diffusion. For this you should look at the Sd value. The lower the better. In any case, it should be smaller than 0.14 m.

Silicate paint or lime paint: which is better against mold?

Our ancestors, who used to regularly whitewash their walls, already knew that lime coatings protect the walls from mold growth due to their alkalinity. However, this protection only works for a comparatively short time. This is due to the fact that the pH value in coatings with classic lime paints drops relatively quickly due to carbonization.

It is different with silicate paints. With them, the alkalinity remains permanently - this was also shown by a long-term study by the Mykon Institute at the University of Innsbruck.

What are silicate paints?

Silicate paints, also known as water glass paints or germ paints (after the inventor Adolf Wilhelm Keim), contain water glass (potassium silicate) as a binding agent. This forms a solid chemical bond with the lime and cement components of the plaster, it silicifies.

This means that interior silicate paints can only fulfill their buffer function if they are applied to mineral substrates. The substrate must not be soluble in water. For example, gypsum is a water-soluble material that cannot bond with a silicate paint. So you can't just paint a woodchip wallpaper with silicate paint.

According to the federal government's ecological building material information system, the silicate paint is therefore only suitable for the following substrates:

  • Plaster (inside and outside),
  • Concrete (inside, outside only to a limited extent),
  • Fiber cement (inside, outside only to a limited extent)

Since silicate paint in its natural form is free of preservatives, solvents and plasticizers, it is ecologically harmless. It is also the ideal wall paint for allergy sufferers.

Silicate paints can be painted over with silicate paints over and over again.

Three types of silicate paints

Today there are three types of silicate paints:

  1. The pure silicate paint consists of two components: a dry color powder or a paste made in water and the liquid binding agent water glass. These are mixed before processing.
  2. One-component silicate paint, also emulsion silicate paint: It contains up to five percent organic additives and, like emulsion paint, is available in a ready-to-use liquid in a bucket.
  3. The so-called sol-silicate paint has also been available since 2002. It contains a combination of silica sol and water glass as a binding agent. The organic share is also limited to five percent. You can also use sol-silicate paint on non-mineral plasters.

Disadvantages of silicate paints

Silicate paints have a number of advantages and have a mold-inhibiting effect. However, they also have some disadvantages:

  • Silicate paint is quite expensive.
  • You can only get them in specialist shops, not in hardware stores.
  • The paint is alkaline when wet and may therefore only be used with skin and eye protection.
  • It etches on glass and ceramic surfaces, so these must be well covered before painting.
  • Silicate paint can only be thinned to a limited extent with water.
  • It doesn't get along with Tiefengrund.
  • The choice of colors is limited, pastel tones are more possible than strong colors.

Alternative colors for mold prevention

Some commercially available emulsion paints also advertise that they can effectively combat mold. Most of them contain biocides. These are active ingredients that are supposed to destroy harmful organisms such as fungi, but which can often not only be devastating for mold, but are also problematic for people and the environment. Most of these colors scored "unsatisfactory" in ├ľkotest.

Because of the volatile nature of many biocidal active ingredients, experts also doubt whether an appropriately treated paint can have a long-term effect. "Wherever permanently damp or cool conditions exist, I always consider mold growth to be possible over time," says building biologist Manfred Mierau.

Color against mold: there are also limits

Until you fix the mold triggers, even the best anti-mold paint won't change much. So the first step is to find the reason and fix the problem. Mineral paints can regulate the humidity in the room air, but they cannot dry out walls that are wet due to structural damage, for example.