Автор: Michal Dudiak
Статии
- INFLUENCE OF UV RADIATION ON COLOR STABILITY OF NATURAL AND THERMALLY TREATED MAPLE WOOD WITH SATURATED WATER STEAM
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Резюме
The aim of this paper is to present the results of color change on the surface of natural maple wood and thermally treated maple wood with saturated water steam after UV irradiation in Xenotest 450 – simulation of natural wood aging process. Thermally untreated maple wood is white to light white-gray-yellow in color with coordinates L* = 86.6 ± 2.5; a* = 5.3 ± 1.7; b* = 19.3 ± 2.3 in CIE L*a*b* color space. The thermally treated maple wood is brown-red in color with coordinates L* = 65.3 ± 1.4; a* = 10.8 ± 1.3; b* = 19.3 ± 1.3. The surface of samples maple wood with moisture content w = 12% was irradiated in Xenotest 450 with a xenon lamp with UV radiation of 340 nm. Irradiation of the wood surface took place in the exposure cycle A1 for 7 days. While the irradiated surface of the thermally untreated maple wood darkened and acquired a brownish-yellow hue, the brownish-red hue of the thermally treated maple wood turned paled slightly. The total color difference ∆E* caused by UV radiation of thermally untreated maple wood is ∆E* = 15.2 and thermally treated maple wood is ∆E* = 10.8. A comparison of the simulated aging of thermally treated and thermally untreated maple wood in Xenotest 450 suggests that the overall color change of thermally treated wood is 28.9 % less.
Ключови думи: mountain maple, CIE L* a* b* color space, UV radiation, wood color aging simulation
- IDENTIFICATION OF THE COLOR FALSE HEARDWOOD OF FAGUS SYLVATICA L. IN THE COLOR SPACE CIE L*A*B*
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Резюме
The paper presents the differences in the color of native beech wood between the false heardwood and sapwood in the color space CIE L*a*b*. The visual evaluation of the differences in the color of beech wood between the false heardwood and sapwood clearly shows that the color of the false heardwood of beech wood has a reddish-brown color with values on the coordinates L* = 67.5, a* = 12.7, b* = 20.3 compared to sappwood, the color of which is a light white-gray color with a yellowish tinge with values on the coordinates L* = 77.1, a* = 9.5, b* = 18.4. The degree of color difference at the individual coordinates of the CIE L*a*b* beech wood color space between the false heardwood and sapwood indicates the fact that while the brightness of the false heardwood relative to the sapwood is ∆L* = -9.6 smaller, the red values ∆a* = +3.2 and yellow ∆b* = +1.9 in color are higher in the false heardwood in penetration with sapwood beech wood. A comparison of the values of the standard uncertainty of the measurement of the color of the false headrwood with the values of the relative standard uncertainty of the sapwood shows that the variability of the color shades of the brown-red color of the false heardwood is greater than the variability of the sapwood beech wood.
Ключови думи: beech wood, false heardwood, color wood, color space CIE L*a*b*
- INFLUENCE OF COMPONENTS (UV + VIS) OF SOLAR RADIATION ON THE COLOR CHANGE OF UNSTEAMED AND STEAMED BEECH WOOD
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Резюме
The paper presents the differences of color changes of unsteamed and steamed beech wood with saturated water steam with temperature t = 135 °C for τ = 7.5 h caused by long-term exposure of sunlight to the surface of wood in interiors for 36 months. Light white-gray color with a yellow tinge of native beech wood with values on the coordinates of the color space CIE L*a*b* (L* = 76.6, a* = 7.8, b* = 19.8) darkened due to sunlight and the wood turned pale-brown color with a touch of yellow (L* = 71.3, a* = 12.2, b* = 26.8). The degree of darkening and browning is quantified by the value of the total color difference ∆E* = 13.0. The deep brown-red color of steamed beech (L* = 55.3, a* = 14.5, b* = 23.5) brightened during exposure due to sunlight and the wood surface took on a pale brown hue (L* = 77.6, a* = 14.1, b* = 27.8). The degree of lightening of the color of steamed beech wood in the color space CIE L*a*b* is quantified by the value of the total color difference ∆E* = 7.1. A comparison of the color changes of native and steamed beech wood through the total color difference ∆E* due to daylight shows that the surface of steamed beech wood shows 52.2% smaller changes than unsteamed beech wood. The lower value of the total color difference of steamed beech wood indicates the fact that changes in beech wood chromophores caused by steaming steam have a positive effect on color aging due to natural aging and partial resistance of steamed beech to the initiation of photochemical reactions caused wavelengths UV+VIS sunlight.
Ключови думи: beech wood, color space CIE L*a*b*, UV + VIS radiation, color change