Moisture in Paper Webs

Paper converting is important in preparing paper manufactured from wood pulp at mills to be converted to usable paper products from note paper to paper cups, tags, tapes, labels and more.  Paper is the most widely used wrapping, writing, printing and packaging material in the world.

Paper converters need to control moisture to maintain flatness and eliminate edge curl.  If the top and bottom of a paper sheet are at different moisture levels, the sides expand or contract when equilibrated causing curl.  The curl can cause malfunctions (jamming) in the subsequent printing, slitting and packaging unit operations that increases scrap and reduces efficiency.  Converting companies vying for the high-quality performance paper market focus on flat and level sheets.

Summary of Process


Paper can gain or lose moisture based on the surrounding humidity when in transit or storage.  Many converters measure the incoming paper stock prior to coating the paper, to ensure that the coating will be properly applied to the paper substrate.  If the paper moisture is too low, they will run it through a re-moisturizer.  Re-moisturizers can be roll, steam, disk, spray or another implementation technique.  Roll re-moisturizers can be optimized by adjusting applicator roll speed, gap and skew.  Steam re-moisturizers are adjusted by increasing the volume of steam applied to the paper.  Disk re-moisturizers can be adjusted by water volume or disk rotation speed.  Spray re-moisturizers are controlled by water volume or the number of micro-sprays applied per second.

Water Based Coatings

Converters employ different applicators for water based coatings dependent on their needs.  These applicators can be roll, spray, doctor blades, dip, air knives, and other techniques.  These coatings will have a fixed liquid/solids ratio depending on the product.  The wet end water based coating can be measured based on the moisture absorption in the Near Infrared region of the light spectrum.  This measurement will provide the amount of dry end coating deposited on the paper after the dryer in engineering units such a #/ream, GSM, mils or other.

Dryer Control

Dryers can be convection, radiant, infrared or other technique.  Paper moisture can be controlled by web speed through the dryer or dryer temperature.  Typically, web speed is the preferred method as dryer temperature control can be slower to react to system upsets.  Dryer cans are essentially steam heated cylinders where the temperature and contact time control the heat driving off moisture.


Quality Parameters and Measuring Points

Moisture Measurements:  Paper is cellulose based and hydroscopic.  Paper moisture is usually between 3 and 6% moisture in its finished state dependent on surrounding humidity.  NIR transmitters are useful at every unit operation of the converting process including incoming raw material, re-moisturizing stations, coating, drying and data archiving of finished product.

The MCT series of NIR stand-alone transmitters are usually mounted in the center of the web or in series on the left, right and center of the web.  This is of great value to the converter however it doesn’t cover the complete web and as such if a steam valve or disk rotation clogs or fails and it’s not in the path of the fixed transmitter, it will not be detected.  Similarly, if dirt or specks of coating attach to the roll in places where the web isn’t being monitored, streaking can result.

The Guardian Cross Direction Web Profile System supplies a cross direction zoned web profile and machine direction trend for system operation.  The color-coded CD profile visually displays in-spec product as green zones, alerts in yellow and red alarms.  This is often connected to a color-coded Stack Light with annunciator to alert operator when product is in the alarm condition.  Machine Direction Trends allows troublesome zones to be diagnosed and corrected.

Value and Quality

Implementation of Near IR technology to measure moisture at unit operations speeds start up, increasing production, reduces scrap and allows for data archiving by roll or run.  Without an on-line measurement system, the line must be started up, sample collected for laboratory analysis, system optimized and started up again with another sample collected to confirm the optimization.  With an on-line system this process is stream lined resulting in greater efficiency.  The data archiving, whether from fixed or scanning transmitters via Ethernet communications protects against customer complaints and allows data histories to be associated with modifications to unit operations or work shifts.

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PFAS Coating Measurement Is Important In Food Packaging

PFASs are polyfluoroalkyl chemicals commonly used in food packaging due to their resistance to oil, grease, moisture and stain resistance.  They are applied to everything from fast food burger/sandwich wrappers to pizza boxes in food packaging.  PFASs are also used on fabrics such as carpets, furniture and backpacks for stain resistance.

Essentially hydrogen atoms are replaced with fluorine atoms terminating with a Carbon chain.  The PFASs are similar to Teflon (PTFE) used in non-stick frying pans.  The danger with PFASs in food packaging is that if too much of this grease resistant coating is applied in food packaging, it can migrate into the food that we ingest and potentially increase cancer risks.


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Therefore, it’s critical that food packaging suppliers measure and control the amount of PFASs applied to their paper and board lines.  Near Infrared Cross Direction Profile Systems provide this measurement that can be sent to a Programmable Logic Controller (PLC) to precisely control the amount of PFAS being applied and they can also archive data.

Please contact us to discuss your application:  508.473-9901

Moisture Barrier Coating Consumption in Food Packaging Manufacturing

Moisture barrier coatings are used to prevent moisture migration and preserve quality and shelf life of food products.

Many moisture barrier coatings are relatively thin in the order of 0.5 lbs/ream (per 3000 Ft²) or less.  These coatings can easily be measured with Near Infrared Transmitters on printed substrates to optimize the coating thickness and insure a uniform Cross Direction Web Profile.  Measurement data can be archived in roll reports that are time and date stamped for future reference in the event of customer complaints or other issues.  These reports can also be used to compare the performance of different shifts on production runs.

Coatings and adhesive need to be applied in sufficient amount to meet specifications.  Without a method to measure the deposition, many manufacturers apply more coating than needed resulting in a higher production cost.  Too little applied coating will not provide the needed barrier to prevent the migration of moisture that can result in spoilage and an adverse impact on taste, texture and shelf life.

Stopping the line to collect lab samples slows production and does not supply archiving capabilities for roll or production runs.  On-line continuous measurement of coating speeds start up, increases production and in-specification product.

The wet water based coated substrate typically passes through a dryer and then a re-moisturizer where a separate moisture measurement system supplies the output to control the moisture profile and minimize or eliminate lay flat and edge curl issues.

Plant managers are often concerned about coating consumption which impacts the profit margin on specific orders.  Coating calculations determine the amount needed for a specific product run and the cost of coating associated with that product run.  For instance, if a 40 inch wide web with a target of 1 wet lb per 1000 ft squared and an anilox volume of 14 BCM is being manufactured, both the weight in pounds and volume in gallons can be calculated.  If the web width for another version of the same product is increased to 80 inches, the consumption significantly increases but it is not a simple doubling of necessary coating as that is a function of increased area not simply web width.

Near Infrared technology employed on-line can calculate the continuous consumption to aid in monitoring the production run or roll consumption when incorporating other parameters.

Please contact us to discuss your application today at 508.473-9901.


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ICE Europe and ICE USA Feature Guardian

Process Sensors Corp. will be exhibiting our Guardian Cross Direction Web Profile System at the International Converting Expositions in Munich & Orlando.  The Guardian features MCT Nova Series of Near IR Transmitters, Central Console for Multiple Cross Direction and Machine Direction Web Profiles, Web Temperature, Industrial Scanning Frames and Automatic Web Detection.  Software includes scanning speed, number of zones, zone and web average measurements, lane measurement and machine direction options, and data logging for customer archiving.  Ethernet, Ethernet IP, OPC Kepware, Modbus TCP and additional communication options for PLC, Networks and remote viewing.   Please visit with us to discuss your paper, film, foil or other application for moisture, coating, PSA or film thickness, residual moisture or solvent.  Or call us at 508.473-9901



ICE USA is the only dedicated event for the conversion of paper, film, foil, nonwovens and other flexible web-based materials in the Americas and our 2017 event marks the 4th edition of ICE USA. This premier event is where converting professionals gather to see first-hand the latest machinery, technology, and manufacturing solutions. Attendees from around the globe are looking to develop new business partnerships and come ready to network and learn from leaders in the converting industry.


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ICE Europe celebrates the 10th anniversary event from 21-23 March 2017: 86% of exhibition space already booked
The 10th anniversary event of the ICE Europe show will take place from 21-23 March 2017 at the Munich Trade Fair Centre in Germany. The world’s leading exhibition for the conversion of flexible, web-based materials, such as paper, film, foil and nonwovens, targets industry professionals looking for innovative equipment and solutions within the converting sector.



Guardian Multi Frame Multi Display System for CD Profile

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The Guardian Cross Direction Web Profile System can display multiple web profiles from multiple frames.  The Guardian can also display machine direction trends of profiles by zone and temperature profiles.  The Guardian can measure moisture, residual moisture, coat weight, film thickness and other parameters of interest.  Please contact us today at 508.473-9901 to discuss your application.

Reverse Roll Coating Measurement

Reverse Roll Coaters have a metering and applicator roll. Often there are 3 or 4 roll configurations.  Coating is applied through the gap between the metering and applicator roll where the nip pressure and gap control the specific coat weight.  The applicator roll runs in reverse direction of the web transferring the coating onto the web.  Reverse Roll Coaters are capable of producing highly polished surfaces and are more expensive than some other coaters such as slot-die that can’t always achieve that level of polishing.  If a Converter operates a Reverse Roll Coater a Cross Direction Web Profile System is a good investment to maintain uniform coat weight on high end products.  The Guardian Cross Direction Web Profile System meets the application needs for film, foil and paper coat weight and moisture measurements on Reverse Roll and other coaters.

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Let’s Laminate


Lamination is essentially marrying two or more layers of materials together to obtain superior performance characteristics for specific product applications.   Near IR Transmitters are well established to measure moisture and coating thickness in the lamination process.  Cross Direction Web Profilers greatly assist in producing an even in-specification profile of adhesive thickness.  The resulting composite may be designed as a superior moisture or odor barrier, to highlight/protect appearance or gloss, reduce sound transmission, to increase strength or structural stability and many other applications.

Auto windscreens (windshields)  laminate two pieces of glass with a layer of PVB (polyvinylbutyral)  or other suitable polymer to prevent or minimize sharp glass shards from showering on driver and passengers on impact by wrapping the glass surfaces with the polymer.  Near IR can measure the film moisture and thickness.

Converting industries such as Tag, Tape & Labels, Packaging & Release Liners, Textiles and others operate Near IR to measure the adhesive coat weight applied and the moisture after unit operations such as dryers, re-moisturizers and final windup for QC and Process Control.  For converting applications a two roll laminator is often employed with one roll made of neoprene or other suitable rubber and the other roll made of steel or chrome plated.  The rubber roll applies pressure to the adhesive but also allows for compensation of caliper variations.  Nip roll pressure and skew assist in optimizing the process.

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PSTC – PSC Poster Calibration Techniques Featured

Pressure Sensitive Tape Council Meeting Orlando Florida 

A Sticky Affair!


Pressure Sensitive Tape Council is a highly technical conference featuring world class presentations on current and emerging technologies that benefit the tape manufacturing process.  PSTC also has a very collegial feel with technical people who know situations change and friendships remain.  Our Near Infrared Calibration Procedures Poster was featured in the afternoon session.

We appreciate and thank you for our time together at PSTC May 2016!


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PSTC w Customers at Table Top May 2016         PSTC Poster Board Calibration Sampling May 2016

Corrugating Industry Moisture Control

Especially in Food Industry Packaging Applications with Custom Coatings!

The Corrugation Process requires the single face and double facer to match moistures to minimize warpage.  Historically when corrugated board warped, small companies would just have employees flip it over until humidity leveled it out.  Not scientific but functional and at the time economically effective to create good board if time and order delivery allowed.  The increasing demand for corrugated packaging is driving efficiencies.

Times have changed with industry consolidation, importance of short delivery times and need for high quality flat board for folding operations.

Process SensorsMCT460 is a stand-alone Near Infrared Moisture and/or Coating Analyzer.  The Guardian Cross Direction Web Profile System supplies alarms, archiving and much more.  The screen display easily shows the web profile in bright green, yellow and red for in-spec, alert and alarm conditions.

Process Sensors can supply solutions for warpage and coating measurements.  Water based wax coatings can be measured on the wet end at the moisture peak of 1.94µ or on the dry end at the 2.34µ hydrocarbon peak.  Ethernet outputs, Kepware OPC, Modbus TCP allow easy communication for moisture control systems.  Steam Re-Moisturizers, Liquid Application Systems and Sprayers can benefit from moisture and coating measurements to optimize process control.

Additionally, our Process Sensors IR Division can supply all of your Product Temperature and Thermal Imaging needs.  PSC IR excels at understanding and meeting your immediate need through an international network of specialists.

SenWare can supply all your On-Line, Lab and Portable Color Measurement Needs.  Their specialty is in determining if you need full tri-color stimuli that they offer in all formats such as L*a*b*; L,a,b;  RGB etc.  or a simpler version for your needs.  Contact SenWare to discuss your color measurement needs.

We work with leading Re-Moisturizer, Coating and Dryer Suppliers.  Please contact us at:  508.473-9901 to discuss your needs!


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Lane Adhesive Measurement Made Easy

Adhesive lane thickness and moisture measurement across a paper or film web continues to increase with food and other packaging demands.  Instead of coating an entire web for label stock, these applications only coat narrow lanes of adhesive spaced across the web.

Process Sensors has developed a system that is quickly becoming the industry standard for spaced lane adhesive thickness and substrate moisture measurement.  The Guardian Lane Measurement System allows operators to monitor each adhesive lane across the web.

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The Scanning Frame System automatically detects web edges and stores lane locations from the edge to make measurements.  The Near Infrared (NIR) transmitter can measure the coating on the wet end at the 1.94µ water peak or on the dry end at the 2.34µ hydrocarbon peak.  The unique elongated and rectangular angled viewing area for measurement insures accurate measurement on even very narrow stripe/lane widths.

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This Lane Measurement Profile System reduces start up time and scrap.  After start up, systems normally run through and process measurement is less needed unless in closed loop control.  Many small to medium sized companies benefit from these reasonable priced measurement systems but find that after start up and achieving set point, operators don’t always pay attention to profile.  To meet this need, many incorporate Stack Alarms that trigger when any zone goes out of specification to alarm and cause the operator to view the profile and take corrective action (clean or replace a valve, increase actuator pressure, change water disk speed, adjust skew on LAS, etc.).

Data and Roll Reports can be saved and archived for QC and QA needs.


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Stack Alarms

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