Radio tags and invisible ink to rescue European forests
Around 25 million cubic metres of wood are wasted each year in Europe. In an effort to reduce this waste, researchers are developing solutions, such as radio tags and invisible inks, to improve the traceability of individual logs.
This traceability will ultimately give better protection to our forests and improve efficiency in the wood industries, leading to lower consumer prices.
Ten percent of the wood being cut down is being wasted as a result of inefficient material management. Now there are technologies to control this flow of material. The tracing methods allow for a particular log to be sent to the most appropriate sawmill based on the data collected during the falling process.
In northern Sweden tags with radio-frequency identification (RFID) transponders are being trialled for the identifying of pine logs. After each tree has fallen, the dimensions of the log are measured and a special axe is used to insert a tag. The measurements, which are taken by hand, are sent via wifi to the computer in the harvesting machine. The data is then sent to the main office where it is distributed further to the saw mills. It is planned that the measuring of the logs and the inserting of the RFID tag will become an automatic operation of the harvesting machine. The tagging process will then take less than a second and also include information such as the time and the driver of the harvesting machine. These trials are part of a European research project, called Indisputable Key.
Finnish researchers helped to develop the data processing system. The tags have been produced from biodegradable natural fibre. Since some logs are chipped to be used in pulping mills for making paper, the tags could not be made of plastic.
However, using RFIDs is not always the most appropriate method. The are expensive and become fragile in some wood types. At the Royal Institute of Technology (KTH) in Sweden researchers are working on a prototype saw that prints a special ink code on the wood while cutting through the tree. When the log is later on a beltway in a sawmill, special lights enable the code to be read using computer vision and image processing. The equipment must work in all possible weather conditions, which could be minus 40 degree temperatures or plus 40.
Ink codes are tested at a factory in Southern France where one and a half million maritime pine logs are peeled each year to be used in plywood production. The coded data printed onto the logs survives a 16 hour steaming process at approximately 80 degrees Celsius. The logs can then be again identified before being peeled and made into plywood planks. RFID tags also function very well at this factory, but they are still too expensive. The wood processing engineer Robert Golja suggests a new tracing method involving nanoparticles, distributed with invisible ink, forming a code that can be read by a 30 watt laser. The laser measures the spectrum response of the nanoparticles for a specific wavelength. The laser will be able to read codes through snow, ice or even dirt.
With improved traceability the sawmills can alter their wood input to better match manufacturing requirements. Manufacturers receive the correct quality and quantity of wood, saving time in production, and more forest is preserved. In the end the consumers will benefit from this project; they will no longer have to pay for the wood that is harvested and thrown away.