Photodegradation of heat treated hardwood veneers

Dénes, Levente; Lang, Elemer M.

doi:10.1016/j.jphotobiol.2012.09.017

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…tests, respectively [4,27]. Changes observed are similar to those that occurred during accelerated aging or at the beginning of thermal treatment [5,[28][29][30]. This, and the fact that the whole cross section was affected, support the theory of Matsuo et al [3], who claim that colour changes during aging are a consequence of a slow and mild oxidation process.…”

Section: Colour Changessupporting

confidence: 67%

Aging effects on physical and mechanical properties of spruce, fir and oak wood

Sonderegger

Kránitz

Bues³

et al. 2015

Journal of Cultural Heritage

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Section: Colour Changessupporting

confidence: 67%

Aging effects on physical and mechanical properties of spruce, fir and oak wood

Sonderegger

Kránitz

Bues³

et al. 2015

Journal of Cultural Heritage

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“…It appeared that the convection heat treatment caused stronger discoloration on veneer surfaces regardless the wood species when compared to press heat treatment [22]. The dark colour of veneers can easily mask some blemishes and other discolorations on the surface.…”

Section: Introductionmentioning

confidence: 98%

“…Little information addressed the veneers modification of various wood species by heat treatment. Due to their small thickness, veneers need a shorter time of heat exposure at high temperature ranging between 180 and 200°C during their thermo-densification process [22,23]. Such process when applied to solid wood is a fairly long process [23].…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatment on colour changes of black alder and beech veneers

et al. 2016

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In the present study, colour changes in black alder (Alnus glutinosa L. Gaertn.) and beech (Fagus sylvatica L.) wood veneers subjected to heat treatment at 190°C for different time spans were investigated. The potential of CIELab system and near infrared (NIR) spectroscopy were used to evaluate the colour changes. The changes in colour appeared mostly by the reduction in lightness which is related to the degradation of hemicelluloses during heat treatment in both wood species. It was found that black alder discoloured much more than beech veneers under same treatment conditions. NIR spectra revealed that the dark colour that wood veneers get under heat exposure is due to the chemical decomposition of lignin and hemicelluloses. Heat treatment could, therefore, enhance the use of such veneers for value added products in furniture manufacturing as an alternative to expensive tropical species.

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“…Thermal treatments of wood create dark and attractive brown colour, which is highly determined by the applied temperature and treatment time [3][4][5][6][7][8][9][10][11]. The colour modification by thermal treatment is important for those species that have naturally unattractive light grey colour, such as poplar, or those that have highly inhomogeneous colour, such as black locust.…”

Section: Introductionmentioning

confidence: 99%

Colour stability of oil-heat treated black locust and poplar wood during short-term UV radiation

Németh

Tolvaj

Bak

et al. 2016

Journal of Photochemistry and Photobiology A: Chemistry

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A B S T R A C TBlack locust (Robinia pseudoacacia L) samples with high extractive content and poplar (Populus Â euramericana cv. Pannónia) samples with low extractive content were chosen for the test. The specimens were thermally treated at 160 and 200 C in sunflower oil for 2, 4, and 6 h then irradiated by a strong UV emitter mercury lamp up to 36 h. The effects of thermal treatment and UV radiation were monitored by colour measurement. The results indicated that the extractives play an important role in the photodegradation of oil-heat treated wood. Thermal treatments reduced the lightness change effect of photodegradation. The oil-heat treated black locust samples showed similar photodegradation properties independently on the thermal pre-treatment time and temperature. The redness of oilheat treated black locust samples hardly changed during UV radiation proving the photostability of the thermally modified extractives. The redness change of poplar samples caused by UV radiation was partly determined by the temperature of thermal treatment (darkening and lightening also happened). The yellow colour change of the investigated samples showed that the lignin of thermally modified wood undergoes similar photodegradation as that of the untreated natural wood.

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Photodegradation of heat treated hardwood veneers

Cited by 11 publications

References 9 publications

Aging effects on physical and mechanical properties of spruce, fir and oak wood

Aging effects on physical and mechanical properties of spruce, fir and oak wood

Effect of heat treatment on colour changes of black alder and beech veneers

Colour stability of oil-heat treated black locust and poplar wood during short-term UV radiation

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