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When breathability is important and how to measure it?

Many paints are marketed as ‘breathable’. This does not mean that the paint is intended for inhalation, but that the paint allows moisture to pass through them. When choosing a paint, ‘breathability’, or more accurately, steam diffusion, is an important technical factor to be taken into account in prolonging the service life of any material.

The need for breathability of the paint depends on what you are painting. When paint’s steam diffusion is one factor in a building’s moisture-technical functionality, for example, log houses, paint should be breathable. But it is necessary to understand that breathability is not always desirable. For example, when the material to be painted needs protection from rusting, it’s essential to use paint that has very low steam diffusion i.e. ‘non-breathable’ paint.

Steam diffusion is measured with steam diffusion rate (SD value), which is most commonly calculated using a standardized method (ISO 7783: 2018). The smaller the SD value, the more breathable the paint is. For a paint to be classified as breathable, it should have an SD value of 1 or lower. Extremely breathable paints have SD value (EN ISO 7783) sd < 0,14 m.

Based on the wanted features of the paint, ask for the paint SD values to know more about the breathability. However, it should always be remembered that not only does the SD value tell about the breathability of the paint but also the thickness of the coated layer on the surface. For this reason, it should always be remembered to pay attention to choosing the right paint and the layer amount correctly to protect the painted surface as well as possible. For example, the thicker the painted layer is, the less breathable the paint gets. 

How to evaluate paint sustainability?

The main purpose of paint is to protect and prolong the life of materials and act as a barrier against environmental conditions. For many, painting is also an affordable and fast way to decorate and remodel a home. But the question is, how to do this as sustainably as possible, when it is not always easy to identify which paint is more sustainable than another? With this article, we want to help you understand what the most relevant sustainability features of paint are and how you can evaluate them before purchasing.