What is Dew Point?

What Is Dew Point in Industrial Painting?

The dew point is the temperature at which the moisture in the air turns into water droplets. This is also known as condensation. In painting and coating work the dew point is very important. This is because moisture on steel surfaces can cause the coating to fail rust to form, blistering and poor adhesion of the dew point.
Simple Definition
When the surface temperature of the steel gets too close to the dew point temperature water starts to form on the surface of the steel. This invisible layer of moisture can completely ruin the paint application of the dew point.
This is a problem because you cannot see this moisture layer.. It can still cause a lot of damage to the paint application of the dew point.

Why Dew Point Matters in Painting

Before painting inspectors have to check a things. They have to check the air temperature. They also have to check the surface temperature of the steel.. They have to check the relative humidity. Lastly they have to check the dew point temperature of the dew point.
The temperature of the steel surface should normally be least 3°C above the dew point before the coating application of the dew point. This is a rule that is commonly referenced in standards from organizations like AMPP, which used to be called NACE/SSPC.

What is Dew Point

Example

Let us say the air temperature is 30°C.. The relative humidity is 80%. The dew point is 26°C.
If the temperature of the steel surface is 29°C then it is safe to start painting.. If the temperature of the steel surface is 26°C then there is a risk of condensation.. If the temperature of the steel surface is 25°C then the painting should be stopped.

Dew Point Formula

The formula is: the surface temperature minus the dew point temperature should be greater than or equal to 3°C. This means the temperature of the substrate should always be least 3°C higher than the dew point of the dew point.

Problems Caused by Painting Below Dew Point

There are problems that can be caused by painting below the dew point of the dew point. These include flash rusting. There is also blistering.. Peeling of the paint. There are also pinholes.. Poor adhesion of the dew point. Lastly there is coating failure of the dew point.

Tools Used to Measure Dew Point

There are instruments that can be used to measure the dew point of the dew point. These include hygrometers. There are also dew point meters.. Sling psychrometers. Lastly there are surface temperature gauges.
Some popular brands for coating inspection are Elcometer and DeFelsko.

Best Practice

It is always an idea to check the environmental conditions. You should check them before blasting. You should also check them before painting.. You should check them during the coating application of the dew point. Lastly you should check them during curing.
This helps to ensure that the coating will perform well in the term.. It also helps to ensure compliance, with industrial standards of the dew point.