Wyniki wyszukiwania - BazTech

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Aesthetic valuation of tropical wood colour by colorimetry

Vidholdová Z., Iždinský J., Reinprecht L.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2018

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No. 104

302--306

EN

Colorimetric measurements using CIEL * a * b * system are often carried out for the aesthetic evaluation on wooden surfaces. This study aims to characterize the colour of heartwood of twenty one tropical wood species by the CIE-L * a * b * colour system – lightness (L* ), redness (+a* ), yellowness (+b* ), chromaticity (C* ) and hue angle (h° ). Colour coordinate a* shoved a negative correlation against L* , while colour coordinate b* shoved a positive trend against L* , however both with a relatively small significance. No significance was found between the chromaticity C* and the lightness L* . Only for the hue angle h°was observed a more significant positive correlation against the lightness L*.

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Colour changes of beech wood modified with essential oils due to fungal and ageing-fungal attacks with coniophora puteana

Reinprecht L., Hulla M.

Drewno : prace naukowe, doniesienia, komunikaty

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2015

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vol. 58, nr 194

37--48

EN

Fungal attacks on beech wood (Fagus sylvatica L.) samples (25 × 25 × 3) mm were performed using the brown-rot fungus Coniophora puteana over a period of 8 weeks, without or with their previous accelerated ageing in a Xenotest and a drying oven. Due to the fungal and ageing-fungal attacks, respectively, the top surfaces of the reference beech samples obtained a darker yellow-red shade according to the CIE-L*a*b* colour system. Similar changes in the colour coordinates L*, a*, and b* were found for the beech wood modified with the essential oils which were less fungicidal efficient – lavender, sage, tea-tree, and the oil-mixture. On the other hand, the colour changes in the beech wood modified with those essential oils which had a better fungicidal efficiency – birch, clove, oregano, sweet flag, savory, and thyme – were less significant, confirmed by Duncan’s test. Linear correlations with greater or lesser significance were established between the changes in the colour parameters (ΔL*; Δa*; Δb*; ΔE*) and the corresponding mass losses (Δm) of attacked beech wood, the best for positive Δb* which identified its yellowing.

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Comparison of test methods for coatings on wood

Pánek M., Reinprecht L., Čuchranová E.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2014

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No. 88

187--192

EN

The article compares two different testing methods of color changes of wood coatings with varying pigment content and varying surface quality before finishing. For both Xenotest as well as Exterior testing method were set up same conditions of wood surface and all samples were coated by the same amount of paint in three layers. Three different shades of paints were tested and then compared to reference sample without any finishing paint. We also tested influence of girt size to divergence of methods by using two different sizes of abrasives for preparation of finishing. Xenotest method is faster and has only slight differences in pattern of changes in comparison to exterior method but only in case of pigment paints. When transparent finishing patterns of changes were compared differences of methods were increasing while surface quality had very significant influence to color changes in case of Xenotest. To compare and predict quality of paint systems is more suitable to use faster Xenostest but on the other hand for obtaining exact values of color changes long term exterior tests are needed.