Measuring Dew Point: Why Dew Point Matters

The dew point is the point where air is cooled enough to be saturated with water vapor. When the temperature drops below this point, airborne water will condense and form dew on available surfaces.  When it comes to a QA process for paints and coatings, dew point measurement becomes a big deal. Want to know why? We’ve got all the details.  

Why does the dew point matter?

It’s important to know the dew point when painting because water must be able to evaporate more quickly than the solvents in the paint for paint to properly cure. When there is too much moisture and humidity for water to evaporate quickly enough, condensation may form during the application and drying process, stopping the paint from hardening.   

Typically, the optimum temperature for applying paint is 6°C above dew point or, for painting metal surfaces, 3°C above dew point.  

How do you measure dew point? 

The easiest and most efficient way to measure dew point is with a dew point meter. These digital devices are capable of estimating the probability of condensation on a surface by determining the dew point.  

Dew point meters can be useful for use out in the field when working in factories or construction sites and can also be useful in the lab, when testing paints and paint application as part of a QA process.  

Looking for a reliable solution? The TQC Sheen Dewcheck 4 Series 2 – Dewpoint Meter is an incredibly versatile dew point meter designed to measure and record all climate parameters required to treat surfaces. It’s robust, easy-to-use and conforms to ISO 8502-4 & ASTM D3276-07. 

Dew point FAQs 

We’ve got some answers for the most common questions around measuring dew point.  

How do I calculate dew point? 

Dew point is calculated by the measuring relative humidity (%RH), ambient temperature (Ta) and surface temperature (Ts). These three factors can be used to calculate the dew point temperature.  

Is dew point measured in degrees? 

Yes, dew point is measured in degrees. It is measured in degrees because we use degrees to measure the point at which water vapor in the air condenses into dew.  

What is a dew point meter?

A dew point meter is a digital device that is used to determine dew point by measuring several different factors, including the ambient temperature and the surface temperature.  

Paint testing solutions at Industrial Physics 

From dew point testers to vacuum tables, we have all the test and inspect solutions you need for paint, coatings and films. Our innovative specialist testing brand TQC Sheen – a member of the Industrial Physics family – includes a huge range of products and our experts are always here to help, whether you’re at the research and development stage of a new product or simply looking to update your testing line. Find out more about TQC Sheen.