Moisture measurement in paper

Paper has an enormous variety of applications. When it comes to paper quality, “moisture measurement” plays an important role. The size /extent of moisture homogeneity in paper webs can help ensure that the production process runs smoothly. If the moisture homogeneity is inconsistent, problems can arise in the production process or in paper handling. However, there are more paper-related applications that require moisture measurement, such as controlling the moisture content of adhesives in the production of adhesive foil, controlling the drying of the print color, or monitoring moisture in cardboard before packaging.

Therefore a measurement is recommended. Inventech has the right analytical instruments for these applications. We also use a variety of techniques and are the exclusive representative of brands such as Tews, Viavi, IT Photonics and Spectral Evolution.

Methods for the measurement of moisture in paper

There are two different methods for measuring moisture in paper: Near Infrared and Microwave Resonance.

Printing house photo created by senivpetro - www.freepik.com

Measuring moisture in paper with NIR

The in-line moisture measurement method most commonly used in the proces of papermaking is near infrared measurement (NIR). NIR measures spectral lines that depend on the water content of the product. Most papermaking processes have one or more NIR analyzers installed. Often multiple sensors are combined in a displacement system to measure paper thickness, color and moisture at the end of a production line where the completed paper web is rolled up on a reel. The main advantage of NIR is a fast non-contact measurement. An NIR measurement requires thorough calibration and is affected by changes in paper color. The disadvantage of the NIR method when measuring moisture in paper is that the methods must be maintained for a good result. NIR is not suitable for black paper or irregular printed paper. In some cases it is a disadvantage that NIR only detects moisture on the paper surface.

Read about the in-line chlorine dioxide measurement as well

Measuring moisture in paper with the microwave resonance technique

A second in-line measurement method is microwave resonance. Paper is a very homogeneous product and the moisture content of (dry) paper is usually in a range between 3% and 10%. Therefore, the microwave resonance method is very suitable for measuring the moisture content in paper and paper products in-line and in samples. Major advantages of the microwave resonance method come into effect when measuring on paper:

Measurement detects moisture not only on the surface, but also in the core of the product.
The measurement is independent of changes in color and surface texture
Measurement is very accurate
Measurement immediately provides measured values with samples
Measurement is suitable for online applications, including high-speed paper webs
The microwave resonance method provides very accurate results in a moisture range of up to approx. 13%
Moisture of paper samples (cut sheets) can also be measured with special analyzers that work with microwave transmission

More information on measuring moisture in paper

Whether you want to measure moisture in paper rolls, pulp or loose sheets and in-line or at-line (handheld); Inventech has a suitable solution for every application.

Contact our Product Manager Kees van der Sar

Moisture measurement in paper

Accurate moisture measurement in paper for the best quality