On the modelling of colour changes of wood surfaces

Schnabel, Thomas; Zimmer, Bernhard; Petutschnigg, Alexander

doi:10.1007/s00107-008-0293-x

Cited by 30 publications

(21 citation statements)

References 29 publications

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“…Finally F. sylvatica, C. elaeagnoides and H. polyandra presented similar values where during the following months "b" values were reduced (Figure 14). Natural weathering performed by Valverde and Moya (2010) and Schnabel et al (2009) in two tropical timber species showed similar behavior as shown in this study. The values of the variables colour "a" and "b" reduced and after a period of exposition changes in colour tend to remain constant.…”

Section: Changes In Values L* A* Y and B*supporting

confidence: 83%

“…On the other hand, Schnabel et al (2009) found significant differences in the colour change of wood of the same species exposed to different atmospheric conditions.…”

Section: Colour Changementioning

confidence: 87%

“…Hirche (2009) after 18 months of exposition of wood to natural weathering in Pinus silvestris L. established a pattern of the colour change in wood according to the position in which the wood was exposed. Schnabel et al (2009) studied the variation in the colour of Abies alba and Larix decidua wood in two different localities and concluded that changes in colour are different between sites and regression analysis is a suitable method for modeling the effects. In another way Valverde and Moya (2010) evaluated the natural weathering of two coats in wood of Cedrela odorata and Carapa guianensis.…”

Section: Introductionmentioning

confidence: 99%

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Untitled

2015

IJAPR

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Wood exposed to conditions such as sunlight and rain undergoes a phenomenon known as weathering. Colour change and cracks formation in the wood can be evaluated in order to determine the effect of environmental conditions. This study determined the natural weathering of the important trade timber species in Mexico Cordia elaeagnoides, Dalbergia granadillo, Enterolobium cyclocarpum, Hura polyandra, Swietenia humillis, Tabebuia donell-smithii, Tabebuia rosea and Fagus sylvatica as control. The procedure was performed according to EN 927-3. The action of environmental factors was monitored during five months with changes in appearance and colour and cracking formation also determined. The results indicated that Cordia elaeagnoides (ΔE19.7) and Dalbergia granadillo (ΔE 15.9) showed the lowest values in colour change.

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Section: Changes In Values L* A* Y and B*supporting

confidence: 83%

“…On the other hand, Schnabel et al (2009) found significant differences in the colour change of wood of the same species exposed to different atmospheric conditions.…”

Section: Colour Changementioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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2015

IJAPR

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“…However, if the depolymerized lignins and the extractives are washed out using water, the L* value increases (lightening) and values a* and b* decrease [70,71]. Leaching occurs when wood is exposed to weathering in the native state, or if the continuous protective coating layer is damaged [16].…”

Section: Resultsmentioning

confidence: 99%

Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

et al. 2017

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Abstract:The durability of transparent coatings applied to an oak wood exterior is relatively low due to its anatomic structure and chemical composition. Enhancement of the protection of oak wood against weathering using transparent hydrophobic coatings is presented in this study. Oak wood surfaces were modified using UV-stabilizers, hindered amine light stabilizer (HALS), and ZnO and TiO 2 nanoparticles before the application of a commercial hydrophobic topcoat. A transparent oil-based coating was used as a control coating system. The artificial weathering test lasted 6 weeks and colour, gloss, and contact angle changes were regularly evaluated during this period. The changes in the microscopic structure were studied with confocal laser scanning microscopy. The results proved limited durability against weathering of both tested hydrophobic coatings. The formation of micro-cracks causing the leaching of degraded wood compounds and discolouration of oak wood were observed after 1 or 3 weeks of the weathering test. Until then, an oil-based coating film had protected the wood sufficiently, but after 6 weeks the wood was fully defoliated to its non-homogenous thickness, which was caused by the presence of large oak vessels, and by the effects of specific oak tannins. Using transparent hydrophobic coatings can prolong the service life of the exteriors of wood products by decreasing their moisture content. Without proper construction protection against rainwater, the hydrophobic coating itself cannot guarantee the preservation of the natural appearance of wood exteriors.

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“…The color change of wood is the most sensitive indicator of the degradation caused by UV light (Butler et al 2001;Agresti et al 2013;Esteves et al 2008;Schnabel et al 2009;Matsuo et al 2010;Oltean et al 2010). Tolvaj and Faix (1995) examined three coniferous and two deciduous species irradiated by a mercury lamp.…”

Section: Introductionmentioning

confidence: 99%

Effects of Air Relative Humidity and Temperature on Photodegradation Processes in Beech and Spruce Wood

Tolvaj¹,

Popescu²,

Molnár³

et al. 2015

BioResources

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Spruce and beech samples were irradiated by UV light in humid (100% air humidity) and dry conditions to clarify the effects of vapor on photodegradation. UV-irradiated samples were also soaked in distilled water for comparison. The color change and the IR absorption spectra were measured. The wet condition generated considerably greater discoloration than did the dry condition. The intensity of the color change was higher at elevated temperature (53 °C) than at 32 °C. The results showed that the presence of water as vapor increased the degradation of lignin. The nonconjugated carbonyl groups absorbing around 1760 cm -1 were found not to be stable, and the number of these chemical groups decreased in the presence of vapor when compared against the dry condition. The rising temperature amplified this degradation effect.

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On the modelling of colour changes of wood surfaces

Cited by 30 publications

References 29 publications

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Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

Effects of Air Relative Humidity and Temperature on Photodegradation Processes in Beech and Spruce Wood

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