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The colour difference of transparent surface finish on hydrothermally treated beech wood in the interior

Vidholdova Zuzana, Slabejova Gabriela, Smidriakova Maria

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

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2023

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No. 122

89--98

EN

The colour difference of transparent surface finish on hydrothermally treated beech wood in the interior. The paper deals with the influence of ageing of transparent surface finish in the dark and in the light in interior conditions. The colour difference of the tested samples with surface finishes (∆E* ab) was measured after the ageing of native wood and hydrothermally modified wood in the dark and in the light. In the experiment, European beech wood was hydrothermally treated at a temperature of 135 °C under saturated water vapour for 6 hours. Three different types of surface finishes (acrylic-polyurethane, polyacrylic and aldehyde resin, alkyd resin) were applied on the wood surfaces. The colour parameters of the surfaces in the system CIE L*a *b * , chroma ΔC* , and hue angle Δh° were measured immediately after surface finishing and after the ageing in the dark and in the light. The samples were placed behind windows glass in the interior for 60 days. The results of the colour difference ∆E * ab showed that the colour of wood and the colour of the surface finishes was changed after ageing in the dark as well as in the light. The colour difference ∆E * ab was bigger in the light than in the dark. The colour difference was bigger on native wood than on hydrothermally modified wood.

PL

Różnica w kolorze przezroczystego wykończenia powierzchni drewna bukowego poddanego obróbce hydrotermicznej we wnętrzu. Artykuł dotyczy wpływu starzenia przezroczystego wykończenia powierzchni w ciemności i w świetle w warunkach wewnętrznych. Różnica koloru badanych próbek z wykończeniem powierzchni (∆E*ab) została zmierzona po starzeniu drewna rodzimego i drewna modyfikowanego hydrotermicznie w ciemności i w świetle. W eksperymencie europejskie drewno bukowe poddano obróbce hydrotermicznej w temperaturze 135 °C w warunkach nasyconej pary wodnej przez 6 godzin. Na powierzchnie drewna nałożono trzy różne rodzaje wykończeń powierzchni (akrylowo-poliuretanowe, poliakrylowe i żywice aldehydowe, żywice alkidowe). Parametry barwy powierzchni w systemie CIE L*a*b*, chroma ΔC* i kąt barwy Δh° zostały zmierzone bezpośrednio po wykończeniu powierzchni i po starzeniu w ciemności i w świetle. Próbki umieszczono za szybą okienną we wnętrzu na 60 dni. Wyniki różnicy kolorów ∆E*ab wykazały, że kolor drewna i kolor wykończenia powierzchni zmienił się po starzeniu w ciemności i w świetle. Różnica koloru ∆E*ab była większa w świetle niż w ciemności. Różnica koloru była większa na drewnie rodzimym niż na drewnie modyfikowanym hydrotermiczne.

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Effects of different additives in a waterborne polyacrylate coating on selected surface properties of heat-treated finished wood

Nowrouzi Zahra, Mohebby Behbood, Ebrahimi Morteza, Petrič Marko

Drewno : prace naukowe, doniesienia, komunikaty

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2021

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vol. 64, nr 208

63--78

EN

Color changes of thermally modified timber due to different formulations of polyacrylate coating were studied before and after the application of the coatings. Olive leaf extract as a natural antioxidant-bearing additive was added to polyacrylate to examine any changes in color parameters in comparison with other additives. Water contact angle, surface roughness, and the color parameters in L*a*b* coordinates were measured, and any differences (ΔE*, ΔC*, ΔH*, ΔL*, Δa*, Δb*) were also calculated after applying the formulated coats on the thermally modified wood. The results indicated that lightness decreased after coating. The Δa* value was also increased after application of the olive leaf extract to the thermally treated wood. In general, total color change (ΔE*) was increased after coating. Reduction of ΔC* was found in the coating containing TiO2 with 10% antioxidant. Also, ΔH* was increased by the use of the polyacrylate coating containing TiO2, compared with other coatings. Application of all of the formulated coatings on the wood surface led to improvement in the water contact angle over the evolution time. On the other hand, coating of the treated wood was responsible for the formation of a smooth surface in comparison with the uncoated thermally modified timber.

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Colour stability of surface finishes on thermally modified beech wood

Slabejova Gabriela, Šmidriakowá Maria

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

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2021

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No. 114

116--124

EN

Colour stability of surface finishes on thermally modified beech wood. The paper deals with the influence of the type of transparent surface finish on the change of colour of the surfaces of native beech wood and thermally modified wood. At the same time, the colour stability of three surface finishes on the surfaces of native and thermally modified beech wood was monitored. Beech wood was thermally modified at temperature of 125 °C for 6 hours. The thermal treatment was performed in a pressure autoclave APDZ 240, by the company Sundermann s.r.o in Banská Štiavnica. Three various types of surface finishes (synthetic, wax-oil, water-based) were applied onto the wood surfaces. The colour of the surfaces of native wood and thermally modified wood was measured in the system CIELab before and after surface finishing; the coordinates L*, a*, b*, C*ab and h*ab were measured. From the coordinates measured before and after surface finishing, the differences were calculated and then the colour difference ΔE* was calculated. Subsequently, the test specimens with the surface finishes were exposed to natural sunlight, behind glass in the interior for 60 days. The surface colour was measured at specified time of the exposure (10, 20, 30, 60 days). The results showed that the colour of the wood surfaces changed after application of the individual surface finishes; and the colour difference reached a change visible with a medium quality filter up to a high colour difference. The wax-oil surface finish caused a high colour difference on native wood and on thermally modified wood as well. On native beech wood, the lowest colour difference after exposure to sunlight was noticeable on the synthetic surface finish. On the surface of wood thermally modified, after exposure to sunlight, the lowest colour difference was noticeable on the surface with no surface finish.

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Drewno modyfikowane termicznie

Adamczyk-Królak I.

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

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2013

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nr 1(11)

7--13

PL

Artykuł przedstawia krótką charakterystykę drewna modyfikowanego termicznie, jego zalety i wady oraz przykłady zastosowania w praktyce na fasadach budynków mieszkalnych i użyteczności publicznej.

EN

The article presents short characteristic of thermally modified wood, its advantages and disadvantages, and examples of application of these solutions on the facades of residential buildings and public buildings.