scholarly journals Aging of wood: Analysis of color changes during natural aging and heat treatment

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Miyuki Matsuo ◽  
Misao Yokoyama ◽  
Kenji Umemura ◽  
Junji Sugiyama ◽  
Shuichi Kawai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Oxidation Process ◽  
Color Change ◽  
Natural Aging ◽  
Superposition Method ◽  
Wood Color ◽  
Color Changes ◽  
Heat Treated ◽  
Temperature Superposition ◽  
Wood Analysis

Abstract The color properties of aging wood samples from historical buildings have been compared with those of recent wood samples that were heat treated at temperatures ranging from 90°C to 180°C. The results of kinetic analysis obtained by the time-temperature superposition method showed that the color change during natural aging was mainly due to a slow and mild oxidation process. In other words, heat treatment could accelerate the changes in wood color that occur during aging. In one sample, the color change (ΔE* ab ) after 921 years at ambient temperature was almost equivalent to that of heating (artificial aging) approximately for 6.7 h at 180°C. The results have been interpreted that the aging and the subsequent change in wood color begin at the time of tree harvesting.

Comparison of the color and weight change in Paulownia tomentosa and Pinus koraiensis wood heat-treated in hot oil and hot air

BioResources ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. 5574-5585
Author(s):  
Intan Fajar Suri ◽  
Jong Ho Kim ◽  
Byantara Darsan Purusatama ◽  
Go Un Yang ◽  
Denni Prasetia ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Color Change ◽  
Treated Wood ◽  
Pinus Koraiensis ◽  
Weight Changes ◽  
Paulownia Tomentosa ◽  
Wood Color ◽  
Color Changes ◽  
Hot Air ◽  
Heat Treated

Color changes were tested and compared for heat-treated Paulownia tomentosa and Pinus koraiensis wood treated with hot oil or hot air for further utilization of these species. Hot oil and hot air treatments were conducted at 180, 200, and 220 °C for 1, 2, and 3 h. Heat-treated wood color changes were determined using the CIE-Lab color system. Weight changes of the wood before and after heat treatment were also determined. The weight of the oil heat-treated wood increased considerably but it decreased in air heat-treated wood. The oil heat-treated samples showed a greater decrease in lightness (L*) than air heat-treated samples. A significant change in L* was observed in Paulownia tomentosa. The red/green chromaticity (a*) of both wood samples increased at 180 and 200 °C and slightly decreased at 220 °C. The yellow/blue chromaticity (b*) in both wood samples increased at 180 °C, but it rapidly decreased with increasing treatment durations at 200 and 220 °C. The overall color change (ΔE*) in both heat treatments increased with increasing temperature, being higher in Paulownia tomentosa than in Pinus koraiensis. In conclusion, oil heat treatment reduced treatment duration and was a more effective method than air heat treatment in improving wood color.

scholarly journals Effects of vacuum heat treatment and wax impregnation on the color of Pterocarpus macrocarpus Kurz.

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 954-963
Author(s):  
Lin Yang ◽  
Tianqi Han ◽  
Yunxia Liu ◽  
Qin Yin
Keyword(s):  
Heat Treatment ◽  
Atmospheric Pressure ◽  
Color Change ◽  
Vacuum Heat Treatment ◽  
Wood Color ◽  
Heat Treated ◽  
Total Color Change

Pterocarpus macrocarpus Kurz. wood was vacuum heat treated (VHT)　at 120, 150, and 180 °C, under a pressure of 13.3 kPa. Half of the VHT specimens at 120 and 150 °C were subjected to wax impregnation　(WI) for 48 h at 90 °C under an atmospheric pressure. The effect of VHT and WI on wood color were investigated. The results showed that the VHT at 120 and 150 °C resulted in minor changes in lightness (L*), green-red chromatic coordinate (a*), blue-yellow chromatic coordinate (b*), total color change (ΔE*), and chroma (C*). However, the effect of VHT on L*, a*, b*, and C* at 180 °C became more obvious over the duration. After WI, the L*, a*, b*, and C* of the VHT wood at moderate temperatures varied noticeably, showing similar behavior with the VHT wood at 180 °C as L*, b*, and C* decreased and ΔE increased. However, a* increased after WI compared to that of VHT at 180 °C. The wood color of P. macrocarpus Kurz. after WI became reddish and blue, and the color deviation decreased. The wood color was closer to the dark mahogany, which facilitates its further application in rosewood furniture and woodwork art.

scholarly journals COLOR CHANGE — MASS LOSS CORRELATION FOR HEAT-TREATED WOOD

2014 ◽  
Vol 2 ◽  
pp. 345-352 ◽  
Author(s):  
Cristina Marinela Olarescu ◽  
Mihaela Campean
Keyword(s):  
Heat Treatment ◽  
Mass Loss ◽  
Color Change ◽  
Treated Wood ◽  
Untreated Wood ◽  
Cost Effective ◽  
Assessment Procedure ◽  
Mathematical Correlation ◽  
Heat Treated ◽  
Two Parameters

Heat treatment is renowned as the most environmentally friendly process of dimensional stabilization that can be applied to wood, in order to make it suitable for outdoor uses. It also darkens wood color and improves wood durability. The intensity of heat treatment can be appreciated by means of two parameters: the color change occured in wood due to the high temperature, and the mass loss, which is a measure of the degree of thermal degradation. In order to find a mathematical correlation between these two parameters, an experimental study was conducted with four European wood species, which were heat-treated at 180°C and 200ºC, for 1-3 hours, under atmosheric pressure.The paper presents the results concerning the color changes and mass losses recorded for the heat-treated wood samples compared to untreated wood.  For all four species, the dependency between the color change and the mass loss was found to be best described by a logarithmic regression equation with R2 of 0.93 to 0.99 for the soft species (spruce, pine and lime), and R2 of 0.77 for beech. The results of this study envisage to simplify the assessment procedure of the heat treatment efficiency, by only measuring the color – a feature that is both convenient and cost-effective. 

scholarly journals Wood Surface Changes of Heat-Treated Cunninghamia lanceolate Following Natural Weathering

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 791
Author(s):  
Xinjie Cui ◽  
Junji Matsumura
Keyword(s):  
Heat Treatment ◽  
Wood Surface ◽  
Color Change ◽  
Thermal Modification ◽  
Protective Measure ◽  
Surface Color ◽  
Natural Exposure ◽  
Heat Treated ◽  
The Impact ◽  
Cunninghamia Lanceolate

To quickly clarify the effect of heat treatment on weatherability of Cunninghamia lanceolate (Lamb.) Hook., we investigated the surface degradation under natural exposure. A comparison between heat-treated and untreated samples was taken based on surface color changes and structural decay at each interval. Over four weeks of natural exposure, multiple measurements were carried out. Results show that color change decreased in the order of 220 °C heat-treated > untreated > 190 °C heat-treated. The results also indicate that the wood surface color stability was improved via the proper temperature of thermal modification. Low vacuum scanning electron microscopy (LVSEM) results expressed that thermal modification itself had caused shrinking in the wood surface structure. From the beginning of the weathering process, the heat treatment affected the surface structural stability. After natural exposure, the degree of wood structure decay followed the pattern 220 °C heat-treated > 190 °C heat-treated > untreated. Therefore, when considering the impact on the structure, thermal modification treatment as a protective measure to prevent weathering was not an ideal approach and requires further improvement.

scholarly journals Color changes in wood during heating: kinetic analysis by applying a time-temperature superposition method

2010 ◽  
Vol 99 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Miyuki Matsuo ◽  
Misao Yokoyama ◽  
Kenji Umemura ◽  
Joseph Gril ◽  
Ken’ichiro Yano ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Superposition Method ◽  
Color Changes ◽  
Temperature Superposition ◽  
Time Temperature Superposition

scholarly journals Effect of Solution Heat Treatment and Artificial Aging on Compression Behaviour of A356 Alloy

2019 ◽  
Vol 25 (3) ◽  
pp. 281-285
Author(s):  
Dhanashekar MANICKAM ◽  
Senthil Kumar VELUKKUDI SANTHANAM
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Solution Heat Treatment ◽  
Artificial Aging ◽  
A356 Alloy ◽  
Natural Aging ◽  
Static Condition ◽  
Corrosion Properties ◽  
Compression Behaviour ◽  
Heat Treated

Aluminium alloys are subjected to heat treatment to increase the strength and corrosion properties. This paper aims to study the effect of heat treatment on the compression behaviour of A356 alloy under quasi static condition and barreling effect. The various heat treatments are: (i) solution heat treatment of 1 h at 540 °C + natural aging 0 h + artificial aging at 180 °C up to 5.5 h, (ii) solution heat treatment of 3 h at 540 °C + natural aging for 20 h + artificial aging at 180 °C up to 5.5 h, and (iii) solution heat treatment of 6 h at 540 °C + natural aging for 20 h + artificial aging at 180 °C up to 5.5 h. Specially to understand the influence of artificial aging at every 0.5 h up to 5.5 h, the specimens were heat treated. From the results, solutionizing for 1 hr have a better compression strength irrespective of the artificial aging. Natural aging had decreased the ductility but increased the strength property. Artificial aging had a significant effect on the compressive strength and peak strength were obtained at 4 h irrespective of solutionizing heat treatment. Compressive strength increased by 33 % for 1 h of solutionizing and 4 h of artificial aged specimen when compared to non-heat treated alloy. Two mathematical relations discussed in literature were used for calculating the radius of the barreled surface followed by validation. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.20442

INFLUENCE OF HEAT TREATMENT ON AROMA AND COLOR CHARACTERISTICS OF WHEAT BREAD

2021 ◽  
Author(s):  
И.М. ПОЧИЦКАЯ ◽  
Ю.Ф. РОСЛЯКОВ ◽  
В.В. ЛИТВЯК ◽  
Н.В. КОМАРОВА ◽  
Е.И. КОВАЛЕНКО
Keyword(s):  
Heat Treatment ◽  
Color Change ◽  
Consumer Preferences ◽  
Heating Temperature ◽  
Wheat Bread ◽  
Time Interval ◽  
White Bread ◽  
Color Changes ◽  
Color Characteristics ◽  
Essential Contribution

В формировании потребительских предпочтений важная роль отводится внешнему виду и аромату пищевых продуктов. При выпечке хлебобулочных изделий в процессе меланоидинообразования происходит изменение цвета и появление характерного хлебного запаха. Целью работы явилось исследование ароматобразующих веществ и цветовых характеристик белого пшеничного хлеба, подверженного термической обработке. Объектами исследований служили образцы белого пшеничного хлеба, нагревание которых проводили в сушильном шкафу при температурах 90, 120, 150, 180 и 210°С с интервалом в 10 мин на протяжении 2 ч. Исследование летучих компонентов осуществляли методом газовой хроматографии с масс-селективным детектированием. Образцы фиксировали фотоаппаратом Canon EOS 750D. В результате исследований обнаружено более 120 летучих веществ, идентифицировано 76, из них 31 существенно влияет на аромат белого хлеба. В основном это карбонильные соединения и низшие жирные кислоты, а также спирты, сложные эфиры и некоторые серосодержащие соединения. Анализ изменения цветовых характеристик белого пшеничного хлеба показал, что с увеличением температуры нагревания наблюдается значительное потемнение образцов. Если при температуре 90°С происходит еще незначительное изменение цвета, даже после 2-часового воздействия, то при увеличении температуры до 180–210°С цвет образцов хлеба темнеет в первые 10 мин и в последующем меняется незначительно. Таким образом, результаты исследований показали, что температуру и длительность обжарки необходимо оптимизировать для создания наиболее востребованных потребительских свойств продукта. In the formation of consumer preferences FOR food an important role belongs to appearance and aroma. At baking as a result of the melanoid formation process the color changes and typical of bread aroma appears. The purpose of work was studying the aroma-forming substances and color characteristics of the white bread at heat treatment. The objects of the research were samples of white bread heated in a drying oven at temperatures of 90, 120, 150, 180 and 210°C with a time interval of 10 minutes for 2 hours. The volatiles were investigated by gas chromatography with mass-selective detection. The image was recorded on a Canon EOS 750D camera. As a result of the research more than 120 volatile substances were detected, it is identified 76 from which 31 make an essential contribution to aroma of white bread. Basically, these are carbonyl compounds and lower fatty acids, as well as alcohols, esters and some sulfur-containing compounds. An analysis of the change in the color characteristics of white bread showed that with an increase in the heating temperature a significant darkening of the samples is observed. At a temperature of 90°C there is still a slight color change even after a 2-hour exposure to temperature, then as the temperature increases to 180–210°C, the color of the bread samples becomes darker within the first 10 minutes and then changes insignificantly. Thus, the results of research have shown that the temperature and duration of roasting should be optimized to create the most popular consumer properties of the product.

scholarly journals Determination of color-changing effects of bleaching chemicals on some heat-treated woods

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Memiş Akkuş ◽  
Mehmet Budakçı
Keyword(s):  
Heat Treatment ◽  
Scots Pine ◽  
Color Change ◽  
Quercus Petraea ◽  
Treatment Temperature ◽  
Natural Color ◽  
Heat Treated ◽  
Total Color Change ◽  
Time Periods

Abstract The aim of this study was to use bleaching chemicals to remove the discoloration occurring on the surface of wood after heat treatment in order to restore the natural color of the wood. For this purpose, samples prepared from Scots pine (Pinus sylvestris L.), sessile oak (Quercus petraea L.), Eastern beech (Fagus orientalis L.), and Uludağ fir (Abies bornmuelleriana Mattf.) were exposed to heat treatment at temperatures of 140 and 160 °C for time periods of 3, 5, and 7 h. Bleaching solutions S1 (NaOH + H2O2), S2 (NaSiO3 + H2O2), and S3 (H2C2O4) at a concentration of 18% were then applied to the surface of the materials and the color change was determined according to ASTM D 2244 standard. Depending on the heat treatment temperature and duration, an increase in total color change values was detected on the surfaces of the materials and the color of the samples became darker. The total color change values decreased after bleaching with the S2 solution in the heat-treated Scots pine and fir samples, with the S3 solution in the beech samples, and with the S1, S2, and S3 solutions in the oak samples. The findings showed that by using bleaching chemicals to lighten wood materials darkened after heat treatment, it is possible to obtain results close to the natural color values.

The Electropolymerization and Characterizations of Fluorescent Dye Doped Poly(3,4-ethylenedioxythiophene)

2014 ◽  
Vol 552 ◽  
pp. 291-297
Author(s):  
Xin Li ◽  
Fei Yue Liang ◽  
Cong Ju Li
Keyword(s):  
Response Time ◽  
Oxidation Process ◽  
Color Change ◽  
Reduction Process ◽  
Colorimetric Analysis ◽  
Optical Contrast ◽  
Color Changes ◽  
Dye Doping ◽  
Dark Blue ◽  
Pure Pedot

The electrochromic properties of an electrochemical polymerized composite consisted of poly (3,4-ethylenedioxythiophene) doped with fluorescent yellow dye (PEDOT-FY) are reported. The structures of PEDOT-FY were characterized via cycle voltammograms, spectroelectrochemistry and colorimetric analysis. Film of the PEDOT-FY composites with different FY concentrations appears multi-color changes, such as blue violet↔brillant blue, aubergine↔blue grey, magenta↔ aquamarine blue, orange-yellow↔grass-green, claybank↔moss green in the neutral state and the oxidized state respectively, which are different from the pure PEDOT of dark blue (-0.8V) and light blue (1.0V). The response time reaching 90% of the full optical contrast of PEDOT-FY was 3.4s for the oxidation process and 2.6s for the reverse reduction process when the [EDOT]/[FY] is 1:2, however, when the FY concentration decreased to [EDOT]/[FY] =1:0.01, the response time reduced to 1.9s and 1.7s for the oxidation and reduction process respectively, which is equal to that of the pure PEDOT. Additionally, the colorimetric analysis results show that components of yellow and red in PEDOT-FY films become stronger than pure PEDOT film at the whole electrochromic process. It is shown that acid dye doping is an effective method to broaden the color change range of the electrochromic mateials.

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