The study of colour changes under artificial weathering of light red meranti and yellow balau wood from Shorea genus

2020 ◽  
Vol 111 ◽  
pp. 37-42
Author(s):  
Agnieszka Jankowska
Keyword(s):  
Uv Irradiation ◽  
Wood Species ◽  
Wood Surface ◽  
Aging Process ◽  
Colour Change ◽  
Colour Stability ◽  
Artificial Weathering ◽  
Colour Parameters ◽  
Colour Changes ◽  
Weathering Process

The study of colour changes under artificial weathering of light red meranti and yellow balau wood from Shorea genus. This paper deals with the change in colour of selected tropical wood species from Shorea genus such as light red meranti and yellow balau. The artificial weathering method was used to determine the colour stability of wood surface. The used ageing method consisted of alternating soaking wood in water, drying at a temperature of 70°C and UV irradiation exposure. The colour changes were evaluated using CIE L*C*h system. Changes of particular colour parameters (lightness L*, chroma C*, hue h) were determine as well as the total colour change ΔE*. The results showed that tested species of wood change their colour similarly under the influence of the artificial weathering (the changes in the tested wood appearance occurred in similar scope). Surfaces of tested wood species initially became darker and then lighter. The largest changes in intensity of the colour of wood took place at the beginning of artificial weathering process. The intensity of changes decreased with the progress of aging process.

scholarly journals Influence of Natural and Artificial Weathering on the Colour Change of Different Wood and Wood-Based Materials

Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 488 ◽  
Author(s):  
Davor Kržišnik ◽  
Boštjan Lesar ◽  
Nejc Thaler ◽  
Miha Humar
Keyword(s):  
Laboratory Test ◽  
Colour Change ◽  
Natural Weathering ◽  
Blue Staining ◽  
Artificial Weathering ◽  
Blue Stain Fungi ◽  
Colour Changes ◽  
Blue Stain ◽  
Positive Correlations ◽  
The Aesthetic

The importance of the aesthetic performance of wood is increasing and the colour is one of the most important parameters of aesthetics, hence the colour stability of twelve different wood-based materials was evaluated by several in-service and laboratory tests. The wood used for wooden façades and decking belongs to a group of severely exposed surfaces. Discolouration of wood in such applications is a long-known phenomenon, which is a result of different biotic and abiotic causes. The ongoing in-service trial started in October 2013, whilst a laboratory test mimicking seasonal exposure was performed in parallel. Samples were exposed to blue stain fungi (Aureobasidium pullulans and Dothichiza pithyophila) in a laboratory test according to the EN 152 procedure. Afterwards, the same samples were artificially weathered and re-exposed to the same blue stain fungi for the second time. The purpose of this experiment was to investigate the synergistic effect of weathering and staining. The broader aim of the study was to determine the correlation factors between artificial and natural weathering and to compare laboratory and field test data of fungal disfigurement of various bio-based materials. During the four years of exposure, the most prominent colour changes were determined on decking. Respective changes on the façade elements were significantly less prominent, being the lest evident on the south and east façade. The results showed that there are positive correlations between natural weathering and the combination of artificial weathering and blue staining. Hence, the artificial weathering of wood-based materials in the laboratory should consist of two steps, blue staining and artificial weathering, in order to simulate colour changes.

scholarly journals Insight of Weathering Processes Based on Monitoring Surface Characteristic of Tropical Wood Species

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 877
Author(s):  
Agnieszka Jankowska ◽  
Katarzyna Rybak ◽  
Malgorzata Nowacka ◽  
Piotr Boruszewski
Keyword(s):  
Wood Species ◽  
Structural Changes ◽  
Middle Lamella ◽  
Surface Characteristic ◽  
Artificial Weathering ◽  
Tropical Wood ◽  
Weathering Processes ◽  
Short Period ◽  
Wood Section ◽  
Weathering Process

The main aim of the presented research was to compare the influence of selected ageing factors, such as UV radiation and complex artificial weathering methods, on the colour, wettability and roughness changes in garapa, tatajuba, courbaril and massaranduba from South America—tropical wood species that are popular for external usage in European countries. Both processes caused wood surfaces to become darker and turn to shades of brown. The highest total colour changes were shown in courbaril wood (wood with the highest extractives content). The wood surface roughness demonstrated variation, depending on the wood section and measurement direction, and increased after ageing treatments. Changes in surface contact angle were significant after the inclusion of water and drying in the weathering process (wettability decreased). Anatomical analyses of the tested tropical woods revealed structural changes after used artificial weathering treatments (distortion between cell elements, degradation of the middle lamella, micro-cracks in cell walls, thinning and degradation of parenchyma cells, cracks along pits within vessels). As a result of desorption tension, the changes caused by UV irradiation were much smaller than those caused by full artificial weathering. Fourier-transform infrared spectroscopy (FTIR) analysis indicated the occurrence of lignin and hemicelluloses oxidative changes after the weathering process which resulted in the formation of carbonyl and carboxyl compounds. The depolymerisation of cellulose was also identified. The results show that the observed changes may affect the long-term durability of finishes applied over wood subjected to weathering factors for a short period before finishing.

scholarly journals Influence of Different Drinks on the Colour Stability of Dental Resin Composites

2009 ◽  
Vol 03 (01) ◽  
pp. 50-56 ◽  
Author(s):  
Fulya Toksoy Topcu ◽  
Gunes Sahinkesen ◽  
Kivanc Yamanel ◽  
Ugur Erdemir ◽  
Elif Aybala Oktay ◽  
...  
Keyword(s):  
Red Wine ◽  
Artificial Saliva ◽  
Colour Change ◽  
Resin Composites ◽  
Colour Stability ◽  
Dental Resin ◽  
Dental Resin Composites ◽  
Colour Measurements ◽  
Restorative Materials ◽  
Colour Changes

ABSTRACTObjectives: The objective of this study was to evaluate the discolouration effects of artificial saliva, granule lemon juice, coffee (without sugar), coca cola, sour cherry juice, fresh carrot juice and red wine on resin-based composite materials that are commonly used in restorative dentistry.Methods: Colour of four brands of resin composites (Filtek Z 250 (3M Espe), Filtek Supreme (3M Espe), Quadrant (Cavex), Charisma (Heraeus-Kulzer)) of A2 shade was measured after one day of immersion in eight different solutions. Colour measurements were obtained by using a XL-20 Trismus Colourimeter and colour differences (�E) were estimated. For statistical evaluation, analysis of variance (ANOVA), Dunnett and Tukey tests were used at a significance level of 0.05.Results: For the four restorative materials tested, the lowest ΔE values were observed in the artificial saliva, while ΔE values were the highest in red wine group. When comparing the four different restorative materials, Filtek Supreme exhibited the least colour changes whereas Filtek Z250 was the least colour-stable.Conclusions: Dental resin composites and drinking solutions were significant factors that may affect the colour stability. After immersion for one day, all materials showed visible colour changes. The red wine solution exhibited more staining than others in three groups. Filtek Supreme showed significantly the least colour change due to its nano particle sizes. (Eur J Dent 2009;3:50-56)

scholarly journals Colour Stability of Veneering Composites after Accelerated Aging

2010 ◽  
Vol 04 (02) ◽  
pp. 137-142 ◽  
Author(s):  
Triantafillos Papadopoulos ◽  
Aspasia Sarafianou ◽  
Andreas Hatzikyriakos
Keyword(s):  
Colour Change ◽  
Accelerated Aging ◽  
Blue Shift ◽  
Colour Stability ◽  
Before And After ◽  
Indirect Composites ◽  
Colour Changes ◽  
Indirect Composite ◽  
The Mean ◽  
One Way Anova

Objectives: To investigate the colour stability of four indirect composite restorative materials after accelerated aging.Methods: Four indirect composites (Gradia, Signum+, HFO and Adoro) were used. For each material, six specimens were prepared and subjected to accelerated aging (Suntest CPS+, Atlas, Chicago, IL, USA) according to ISO 7491. A Dr. Lange Microcolor Data Station colorimeter (Braive Instruments, Liege, Belgium) was used to measure specimen colour before and after aging. Measurements were performed according to the CIE L*a*b* system, and the mean L*, a* and b* values for each material were calculated. The equation ΔΕ = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2 was used to measure the total colour change (ΔΕ), where ΔL*, Δa* and Δb* are the differences in the respective values before and after aging. One-way ANOVA were used to determine statistically significant differences in ΔL*, Δa*, Δb* and ΔΕ.Results: No statistically significant differences were found in ΔL*, Δa*, Δb* and ΔΕ among the materials tested (PΔL*=.063; PΔa*=.521; PΔb*=.984 and PΔE=.408). After aging, Gradia specimens showed an increase in lightness (ΔL*=0.36) and a green-yellow shift (Δa*=-1.18, Δb*=0.6), while Signum+ specimens exhibited an increase in lightness (ΔL*=0.5) and a green-blue shift (Δa*=-0.9, Δb*=- 0.45). HFO specimens exhibited an increase in lightness (ΔL*=0.75) and a green-yellow shift (Δa*=- 1.3, Δb*=0.06), and Adoro specimens exhibited an increase in lightness (ΔL*=2.07) and a green-yellow shift (Δa*=-1.3, Δb*=0.68).Conclusions: Colour changes were found to be within accepted values of perceptibility and clinical acceptance after accelerated aging, and no statistically significant differences were found in ΔL*, Δa*, Δb* and ΔΕ among the materials tested. (Eur J Dent 2010;4:137-142)

scholarly journals The relationship between colour and pH in cold-stored quail breast muscle / Zależność między barwą a pH w mięśniach piersiowych przepiórek przechowywanych w warunkach chłodniczych

2013 ◽  
Vol 13 (2) ◽  
pp. 401-413 ◽  
Author(s):  
Tadeusz Karamucki ◽  
Józefa Gardzielewska ◽  
Małgorzata Jakubowska ◽  
Kinga Rybak ◽  
Justyna Garczewska
Keyword(s):  
Sensory Evaluation ◽  
Breast Muscle ◽  
Colour Stability ◽  
Muscle Ph ◽  
Old Japanese ◽  
Colour Parameters ◽  
Colour Changes ◽  
Hue Angle ◽  
Ph Range ◽  
High Degree

Abstract The purpose of this study was to analyse the colour of the breast muscles of Japanese Pharaoh quail on the first day after slaughter and again after further six days of cold storage, in relation to their muscle pH. The material for the study consisted of 40 breast muscles taken from the carcasses of six-week-old Japanese Pharaoh quail. Based on pH results, the muscles were divided into three groups: I (pH = 5.51-5.70), II (pH = 5.71-5.90) and III (pH = 5.91-6.10). After this the muscles were stored for a further 6 days at 4°C. It was found that the pH of freshly dissected quail breast muscle is a good indicator of the colour stability of muscles cold-stored at 4°C for six days. The lowest degree of colour stability was observed in the pH range 5.51-5.70. In the sensory evaluation muscles displaying this degree of colour instability were considered unacceptable or barely acceptable. In contrast, muscles in the pH ranges 5.71-5.90 and 5.91-6.10 displayed a high degree of colour stability and were considered acceptable in the sensory evaluation. The colour changes that occurred during storage of the muscles were due to changes in the values of all of the colour parameters (L*, a*, b*, C* and hº); however, the greatest changes were found in the case of redness (a*) and the hue angle (hº). The changes were caused both by alterations in the amount of pigment reached by light, and by changes in the relative amounts of the chemical forms of myoglobin.

scholarly journals Disparity in Discolouration of Thermally Modified Wood Exposed to Solar and Artificial Ultraviolet Irradiation

2015 ◽  
Vol 34 (329) ◽  
pp. 12-20
Author(s):  
Dace Cirule ◽  
Edgars Kuka ◽  
Andis Antons
Keyword(s):  
Uv Irradiation ◽  
Colour Change ◽  
Solar Irradiation ◽  
Chemical Transformations ◽  
Uv Spectrum ◽  
Colour Parameter ◽  
Colour Parameters ◽  
Thermally Modified Wood ◽  
Artificial Uv ◽  
Modified Wood

Abstract Artificial weathering is a widely used method for predicting wood behaviour during its service life. A study was carried out to compare the colour change of thermally modified aspen (Populus tremula L.) and grey alder (Alnus incana (L.) Moench) wood during natural solar and artificial ultra violet (UV) irradiation. Thermally modified wood specimens were exposed for 30 h to artificial UV irradiation at two different intensities, i.e.1.36 W m−2 at 340 nm and 0.68 W m−2 at 340 nm, as well as to solar irradiation outdoors and indoors. After 2.5, 5 and 10 h exposure, colour parameters and reflectance spectra (360–740 nm) were determined. Colour was expressed in accordance with the CIELAB colour model as colour parameters L*, a*, b*. The total colour change ΔEab was calculated from colour parameter differences ΔL*, Δa*, Δb*. The colour changes caused by solar and artificial UV irradiation had a similar pattern for both thermally modified hardwood species under study. Changes in the individual colour parameters in the course of the experiment altered their direction, which implies that discolouration of thermally modified wood is a complicated and dynamic process with various and different chemical transformations in wood chromophores. Colour and reflectance changes had similar trends for different intensities of the same type of irradiation, but they differed for various irradiation types – natural solar or artificial UV irradiation. Greater discolouration was detected for the specimens exposed to both solar irradiations - outdoors and indoors. The results suggest that the fluorescent lamps of the UVA-340 type, which only imitate well the sunlight UV spectrum from 290 nm to 365 nm, do not fully simulate the changes in thermally modified wood induced by solar radiation.

scholarly journals Explaining Colour Change in Pyrope-Spessartine Garnets

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 865
Author(s):  
Yan Qiu ◽  
Ying Guo
Keyword(s):  
Solid Solution ◽  
Colour Change ◽  
Light Sources ◽  
Absorption Bands ◽  
Incandescent Light ◽  
Peak Absorption ◽  
Vis Spectroscopy ◽  
Colour Parameters ◽  
Colour Changes ◽  
External Light Source

A colour-changing garnet exhibits the “alexandrite effect”, whereby its colour changes from green in the presence of daylight to purplish red under incandescent light. This study examines this species of garnets as well as the causes of the colour change by using infrared and ultraviolet visible (UV-Vis) spectroscopy. The infrared spectra show that the colour-changing garnets in this paper belong to the solid solution of pyrope-spessartine type. CIE1931 XYZ colour matching functions are used to calculate the colour parameters influencing garnet colour-changing under different light sources. The UV-Vis spectra show two zones of transmittance, in the red region at 650–700 nm and the blue-green region at 460–510 nm. As they exhibit the same capacity to transmit light, the colour of the gem is determined by the external light source. The absorption bands of Cr3+ and V3+ at 574 nm in the UV-Vis spectra are the main cause of the change in colour. With the increase in the area of peak absorption, the differences in the chroma and colour of the garnet gradually increase in daylight and incandescent light, and it exhibits a more prominent colour-changing effect.

scholarly journals Alteration of Tissue Marking Dyes Depends on Used Chromogen during Immunohistochemistry

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 835
Author(s):  
Selina Kiefer ◽  
Julia Huber ◽  
Hannah Füllgraf ◽  
Kristin Sörensen ◽  
Agnes Csanadi ◽  
...  
Keyword(s):  
Colour Change ◽  
Residual Tumour ◽  
Blue Colour ◽  
Close Margin ◽  
Correct Orientation ◽  
Therapeutic Regime ◽  
Colour Changes ◽  
Tissue Specimens ◽  
Immunohistochemical Analyses ◽  
Colour Signal

Pathological biopsy protocols require tissue marking dye (TMD) for orientation. In some cases (e.g., close margin), additional immunohistochemical analyses can be necessary. Therefore, the correlation between the applied TMD during macroscopy and the examined TMD during microscopy is crucial for the correct orientation, the residual tumour status and the subsequent therapeutic regime. In this context, our group observed colour changes during routine immunohistochemistry. Tissue specimens were marked with various TMD and processed by two different methods. TMD (blue, red, black, yellow and green) obtained from three different providers (A, B and C, and Whiteout/Tipp-Ex®) were used. Immunohistochemistry was performed manually via stepwise omission of reagents to identify the colour changing mechanism. Blue colour from provider A changed during immunohistochemistry into black, when 3,3′-Diaminobenzidine-tetrahydrochloride-dihydrate (DAB) and H2O2 was applied as an immunoperoxidase-based terminal colour signal. No other applied reagents, nor tissue texture or processing showed any influence on the colour. The remaining colours from provider A and the other colours did not show any changes during immunohistochemistry. Our results demonstrate an interesting and important pitfall in routine immunohistochemistry-based diagnostics that pathologists should be aware of. Furthermore, the chemical rationale behind the observed misleading colour change is discussed.

scholarly journals Indicator Layers Based on Ethylene-Vinyl Acetate Copolymer (EVA) and Dicyanovinyl Azobenzene Dyes for Fast and Selective Evaluation of Vaporous Biogenic Amines

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4361
Author(s):  
Tinkara Mastnak ◽  
Aleksandra Lobnik ◽  
Gerhard Mohr ◽  
Matjaž Finšgar
Keyword(s):  
Biogenic Amines ◽  
Vinyl Acetate ◽  
Colour Change ◽  
Ethylene Vinyl Acetate ◽  
Yellow Orange ◽  
Colour Changes ◽  
Limit Sensitivity ◽  
Linear Concentration Range ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

The article presents naked-eye methods for fast, sensitive, and selective detection of isopentylamine and cadaverine vapours based on 4-N,N-dioctylamino-4′-dicyanovinylazobenzene (CR-528) and 4-N,N-dioctylamino-2′-nitro-4′-dicyanovinylazobenzene (CR-555) dyes immobilized in ethylene-vinyl acetate copolymer (EVA). The reaction of CR-528/EVA and CR-555/EVA indicator layers with isopentylamine vapours caused a vivid colour change from pink/purple to yellow/orange-yellow. Additionally, CR-555/EVA showed colour changes upon exposure to cadaverine. The colour changes were analysed by ultraviolet–visible (UV/VIS) molecular absorption spectroscopy for amine quantification, and the method was partially validated for the detection limit, sensitivity, and linear concentration range. The lowest detection limits were reached with CR-555/EVA indicator layers (0.41 ppm for isopentylamine and 1.80 ppm for cadaverine). The indicator layers based on EVA and dicyanovinyl azobenzene dyes complement the existing library of colorimetric probes for the detection of biogenic amines and show great potential for food quality control.

Formation of Green Pigment and Colour Changes in Orthoptera

1953 ◽  
Vol 44 (2) ◽  
pp. 299-315 ◽  
Author(s):  
Salâhattin Okay
Keyword(s):  
Fat Body ◽  
Colour Change ◽  
Blue Pigment ◽  
Breakdown Product ◽  
Bile Pigment ◽  
Green Pigment ◽  
Yellow Colour ◽  
Blue Component ◽  
Colour Changes ◽  
Background Reaction

The colour change and formation of green pigment in Mantis, Acrida, Locusta, Schistocerca and Dixippus are studied.There is no background reaction to green and brown or yellow colour in these species.Usually the young nymphs of Mantis are green; some ofthe old nymphs and adults have a tendency to lose the green pigment. Phytophagous nymphsbecome green only when fed on fresh or growing grass. Green individuals may be obtained in darkness on this food (Locusta). The green pigmentdisappears on a diet of dry grass.The colour change from non-green to green, or vice versa, is dependent on the formation or disappearance of the blue component (bile pigment-protein) of green pigment. The blue pigment generally appears first in the blood and is deposited in the integument at the following moult; it does not appear to be a breakdown product of chlorophyll or haematin. It is probably synthesised from a colourless precursor in the peripheral fat body.Observations made on the pericardial cells of Locusta suggest that the blue pigment may be converted into insectorubin.

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