The determination of the dew point

As a basis for successful corrosion protection.

From certain differences between the air and surface temperature and with correspondingly high humidity, water vapor may condense on surfaces. However, this must be avoided at all costs when coating in heavy corrosion protection. It is therefore important to keep an eye on the dew point during painting.

This is how the determination of the dew point works.

The dew point indicates the surface temperature at which the water vapor in the air would condense. The higher the air temperature, the more water vapor it can absorb. As the temperature drops, the air's absorption capacity falls and condensation occurs.

This phenomenon plays a major role in corrosion protection. If the surface is not completely dry during coating, this can severely impair the adhesion properties of the paint.

The dew point or dew point temperature is determined on the basis of the air temperature, the surface temperature of the part to be coated (such as steel beams) and the relative humidity. The object temperature is the decisive factor. If the surface is colder than the surroundings, the surface may mist up. According to DIN EN ISO 12944, the object temperature must be at least 3 °C higher than the dew point during the entire coating work.

Where is this process used?

  • Paint coatings, protective coatings on steel components or steel ship hulls for high-performance corrosion protection

What factors can influence the measurement?

If the housing grid is covered by gloves or otherwise, incorrect measured values for humidity and air temperature may occur.

Which standard is applied here?

Determination of the dew point according to DIN EN ISO 12944