Paper Pulp Moisture

Implementing Moisture Control

After disembarking, the bark that contains a few useful fibers is typically utilized as fuel to generate steam for the pulp mill. To ensure fuel efficiency, this bark must be as dry as possible. This is where the utilization of online, near-infrared (NIR) moisture meters becomes significant. These meters instantly and continuously measure the moisture content, aiding in the efficient utilization of fuel. However, it is not only the dry bark portion of the pulp industry that requires careful monitoring and adjustment of moisture content. Market pulp, which is intended for shipment to other locations where it will be converted into paper, also necessitates attention to moisture levels. Normally, it must be delivered with a moisture content of approximately 10% in bales. The IR3000 moisture sensor is employed to monitor this moisture level, minimizing fiber-to-fiber bonding and facilitating the dispersion of pulp in water during subsequent processing. Other types of pulp are dried to 5-6% and supplied in rolls, making online moisture measurement essential once again.

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To achieve the desired moisture percentage, it is crucial to measure at various stages throughout the process. For instance, certain types of pulp begin with a moisture content of 50% and undergo flash drying in a vertical silo using hot air treatment to meet specific standards. At this stage, there is a risk of incineration if the pulp becomes too dry before entering the hot air silo.

All finished papers produced from pulp have a moisture percentage ranging from approximately 2% to 12%, depending on ambient conditions. The type of pulp, refining method, and chemicals used in manufacturing also influence the moisture content. The moisture level must fall within this range, as any deviation can negatively impact every physical property of the paper. By implementing an accurate and efficient moisture level monitoring system throughout the process, one can optimize the outcome and ensure the best possible results for all involved.


Our equipment never comes into contact with the product, allowing for less waste

zero drift

Our sensors are guaranteed not to drift over time – which saves time and money

closed loop

Create a closed-loop process by tying a moisture sensor into your PLC. Full control over the line!

no recalibrations

We’ve mastered the art of moisture sensors – your unit will never need to be recalibrated for the same product twice!

Paper Web & Coating

Paper is an incredibly eco-friendly product, with two-thirds of it being recycled and the majority of the remaining raw material sourced from renewable trees. It is utilized in various forms such as note paper, paper cups, tags, tapes, labels, and more, making it the most widely used material for wrapping, writing, printing, and packaging worldwide. The process of paper conversion involves transforming paper produced by mills into usable manufactured goods. This conversion entails processing a continuous thin sheet of material (known as a web) into a different form. For instance, to create a book, paper may undergo coating, printing, cutting, gluing, and binding, all in a continuous manner. Companies involved in paper conversion must ensure the production of high-quality, flat, and level sheets. If the moisture levels differ between the top and bottom of a paper sheet, it can lead to expansion or contraction of the sides, resulting in edge curl. This curling can cause issues such as jamming during subsequent printing, slitting, and packaging operations, leading to production delays, increased waste, and reduced efficiency. Therefore, it is crucial to monitor and control the moisture content throughout the process to maintain flatness and eliminate edge curl.

Most moisture sensing equipment finds it difficult to detect small concentration fluctuations in the content of moisture of the paper pulp at the wet end of production since moisture content is 90%-96%. The IR-3000 can give readings with adequate resolution.

Typical moisture accuracy is about ± 0.05%, with coating accuracy varying from 0.1 to 0.01 micron, depending on the coating type. A typical analog range is 0-10% moisture. The outputs can be adjusted to optimize recording requirements or PLC.

Re-Moisturizers: Paper moisture levels can fluctuate due to the surrounding humidity during transportation or storage. Prior to coating, converters often measure the moisture content of the paper to ensure proper application of the coating. Re-moisturizers, such as roll, steam, disk, or spray techniques, can be utilized to adjust moisture levels if they are too low. For roll re-moisturizers, adjustments can be made to the applicator roll speed, gap, and skew. Steam re-moisturizers require an increase in steam volume, while disk re-moisturizers can be adjusted by water volume or disk rotation speed. Spray re-moisturizers are controlled by water volume or the frequency of micro-sprays applied per second. Regardless of the method used, monitoring and measuring moisture levels is crucial.

Dryer Control

Dryers, which are heated cylinders used to remove moisture, can be convection, radiant, infrared, or another type. Paper moisture can be regulated by adjusting the web speed through the dryer or by changing the temperature of the dryer. Typically, adjusting the web speed is preferred as it is a quicker method compared to controlling the dryer temperature.

What is the Solution?


Locate the point in the production process in which measuring moisture will be the most crucial and beneficial. Identify how you will use the moisture measurement data for improvements and if it will tie into your PLC.

Remember this could involve more than one installation point!


We offer service and support throughout the world for our moisture measurement sensors and would be happy to connect you with a rep in your area. Contact us today for more information!

Understand the Process

Having the precise moisture levels of paper products in converting operations, newsprint, tissue and corrugated liner pulp has become a critical component during production.