An antibacterial liquid sprayed on a surface
 A Finnish research project has found that the tannins in resin and wood bark have antimicrobial properties that can be used to clean surfaces in, for example, hospitals more safely and environmentally friendly. Image: Maridav / Adobe

VTT: Wood-based coatings reduce microbes on surfaces

Resins and tree-bark tannins have antimicrobial properties with applications in hospital settings, according to VTT Technical Research Centre of Finland.

Aleksi Teivainen


VTT in October reported that antimicrobial solutions developed from resin and tree bark have been found to be viable alternatives to plastics for coating surfaces in Central Finland Central Hospital in Jyväskylä. Tests carried out in the hospital over two months, it said, revealed a pronounced difference in the number of microbes between curtains treated with the wood-bark tannins and ordinary curtains.

“The tannin level reduced the total number of bacteria in the curtain by as much as 60 per cent,” told Matti Virkkunen, senior scientist at VTT. “In addition, further testing showed that the effectiveness can be enhanced by lightly moistening the tanning coating, thereby improving the contact between the bacteria and the tannins.”

A resin droplet on a tree.

Resins and tree-bark tannins are substances that protect plants from mould, bacteria, fungi and parasites. Image: Yanikap / Adobe

Tests were conducted in the hospital also with more easily cleaned and dirt-resistant coatings, showing that the hygiene levels of coated areas are nearly a third higher than uncoated ones.

Also participating in the project were private companies, JAMK University of Applied Sciences and the Central Finland Health Care District. The participants identified ultraviolet (UV) camera technology as the most effective method to evaluate the results of cleaning and detect impurities on surfaces.

Jaana Mäkelä, specialist at the Jyväskylä University of Applied Sciences, said UV cameras revealed impurities that could not be detected under regular illumination.

“One target of testing was the accumulation of contamination on the door handles of a school building. Photographs of the door handle samples taken with a UV camera revealed spots indicating both the presence of dirt and a deterioration of the antimicrobial coating even though they appeared to be clean,” she told.

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