PERCEPTION OF THE SUMMER 2020

Measurement of wood moisture

#PoM – Wood Moisture Measurement

The wood industry is undergoing a massive change. The quality requirements of customers are increasing. The measurement of humidity is an important quality marker for professional wood processing. To identify the level of moister you can now use hyperspectral imaging to have a fast, accurate indication of the moisture level of the wood.

The Experiment 

The change in the relative humidity of the surrounding air causes wood to gain or lose water moisture. Wood is therefore hygroscopic. The wood moisture content (MC) is a major quality degree and influences the price. It is an important indicator in the wood processing industry for all producers who want to achieve higher margins through better quality. We measured the moisture level of three samples of spruce wood using hyperspectral technology and a regular wood moisture meter.

The Measurement

After the initial measurement, the wood samples were left to soak in water for approximately 1 hour. Next step was to measure the moister again and then leave to air-dry. Humidity measurements have been processed three more times after 0.5 hours, 1 hour and 1.5 hours of drying. A model was created to determine the wood moisture based on hyperspectral imaging.

 

Measurement data

Wood Sample

Sample 1

Sample 2

Sample 3

Sample Avg

Sample 1 after 1hrSample 2 after 1hrSample 3 after 1hrSample Avg after 1hrSample 1 after 0.5hr dryingSample 2 after 0.5hr dryingSample 3 after 0.5hr dryingSample Avg after 0.5hr dryingSample 1 after 1hr dryingSample 2 after 1hr dryingSample 3 after 1hr dryingSample Avg after 1hr dryingSample 1 after 1.5hr dryingSample 2 after 1.5hr dryingSample 3 after 1.5hr dryingSample Avg after 1.5hr drying

Spruce/Reference

5.45.15.25.217.818.8

17.7

18.111.215.511.112.610.514.711127.911.110.69.9

Spruce/Hyperspectral

ufcufcufcufcufcufcufcufc11.715.211.312.79.512.510.410.88.39.89.49.2

used for calibration = ufc

 

Therefore we used the initial measurement and the measurement immediately after soaking from the wood moisture meter. As the wood moisture meter only measures locally the same areas were selected for the hyperspectral measurement.

Conclusion

Hyperspectral imaging was tested in this perception of the month for its ability to monitor the moisture content (MC) of wood samples. The test shows high predictive accuracy. Its accuracy is similar to the accuracy that can be obtained with electromagnetic transmittance meters. HSI measures the moisture at a distance and this does not damage the wood.

The main advantages of Hyperspectral Imaging are:

  • Fast measuring times
  • Locally resolved moisture measurement -> moisture distribution can be determined.

 

More information about quality measurements of wood can be found here:

https://www.osapublishing.org/jnirs/abstract.cfm?uri=jnirs-18-6-507

https://www.degruyter.com/view/journals/hfsg/67/3/article-p307.xml

Development of moisture measurement (Model): Perception STUDIO

Application of humidity measurement on camera live data: Perception CORE

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