The potential of colour measurement for strength prediction of thermally treated wood

Johansson, Dennis; Morén, Tom

doi:10.1007/s00107-005-0082-8

Cited by 109 publications

(61 citation statements)

References 2 publications

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“…Similar changes in MOE and MOR have been reported in the literature. Previous studies showed that heat treatment caused a decrease in MOR of from 1% to 72% and in MOE of from 1% to 40% (Johansson and Morén, 2006;Esteves et al, 2007;Shi et al, 2007;Korkut, 2008). In general, control samples yielded significantly higher bending strength values than those of heat-treated samples.…”

Section: Discussionmentioning

confidence: 91%

Mechanical properties of heat-treated wooden material utilized in the construction of outdoor sitting furniture

Tankut¹,

Tankut²,

Zor³

2014

Turk J Agric For

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The present study examined the bending moment capacity and rigidity of T-type out-of-plane furniture joints and investigated the effects of heat treatment, wood species, and joint type factors on these joints. Heat treatment method clearly decreased the modulus of rupture (MOR) and the modulus of elasticity (MOE) of selected wood species. The bending strength of wood samples was reduced after the heat treatment, decreasing with increased loss of mass. For the heat-treated T-type joints, maximum bending strength values were obtained with Iroko (Chlorophora excelsa) for both mortise and tenon (MT) joints and blind MT (BMT) joints. The lowest reduction in bending strength was observed in Ash (Fraxinus excelsior L.) constructed with MT joints and with BMT joints. In general, the BMT joint had higher bending strength than MT joints. The best rigidity constant (7.21) was obtained with control Iroko BMT joints, while the worst rigidity constant (15.10) was obtained with control Oriental spruce (Picea orientalis L.) MT joints. In terms of heat-treated samples, the best rigidity constant (7.59) was obtained with Black pine (Pinus nigra L.) MT joints, while the worst rigidity constant (14.01) was obtained with Oriental spruce BMT joints. The maximum performance in joint stiffness was determined for Iroko sample BMT joints and Iroko MT joints. Lowest reduction in joint stiffness was observed in Scotch pine MT joints and Ash BMT joints. Heat treatment, wood type, and joint type had a significant effect on the bending strength of T-type MT post-rail joints. BMT joints produced from heat-treated Iroko wood can be considered as the most durable T-type joint for outdoor sitting furniture construction.

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Section: Discussionmentioning

confidence: 91%

Mechanical properties of heat-treated wooden material utilized in the construction of outdoor sitting furniture

Tankut¹,

Tankut²,

Zor³

2014

Turk J Agric For

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“…In previous studies on thermally treated birch wood (175-2008C for 1-10 h in steam) non-homogenous distribution of color was observed (Johansson and Morén 2006). Obviously, during the heat-treatment in air or steam, migration of extractives towards the surface leads to the formation of unsightly resin spots in wood (Mayes and Oksanen 2002).…”

Section: Migration or Removal Of Extractives And Other Compoundsmentioning

confidence: 92%

Changes in chemistry, color, dimensional stability and fungal resistance of Pinus radiata D. Don wood with oil heat-treatment

Dubey¹,

Pang²,

Walker³

2012

Holzforschung

104

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Pinus radiata wood specimens were heat-treated at 160-2108C in linseed oil and the effects of treatment on chemical composition, color, dimensional stability, and fungal resistance were examined. The degradation of hemicelluloses was the most remarkable feature, which is the principal reason for alterations in wood properties. Removal or migration of extractives, oil uptake and the accumulation of oil on the wood surface were observed. The color of heattreated wood became more uniform and darker, and its dimensional stability (i.e., anti-swelling efficiency) and fungal resistance were improved by up to 60% and 36%, respectively. The viscosity of the oil after treatment was elevated with the treatment temperature and was higher in comparison to heated oil without wood present.

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“…However, Johansson and Moren (2006) believe that colour is not suitable as predictor of heat treated wood quality because colour distribution through the thermally treated boards is not homogeneous. As a matter of fact, have found that colour of the Pine wood (Pinus pinaster L.), heat-treated under steam pressure process at 190°C during 6 hours, was not uniform because of the increased contrast between earlywood and latewood, and therefore the color of samples depended on the earlywood/latewood ratio from the sample surface.…”

Section: Durability Prediction By Colour Measurementmentioning

confidence: 99%

Control of wood thermal treatment and its effects on decay resistance: a review

Candelier

Thévenon

Pétrissans

et al. 2016

Annals of Forest Science

182

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Key message An efficient use of thermal treatment of wood requires a depth understanding of the chemical modifications induced. This is a prerequisite to avoid problems of process control, and to provide high quality treated wood with accurately assessed properties to the market. Properties and structural anatomy of thermally modified woods are slightly different than un-processed woods from a same wood species. So it is necessary to create or adapt new analytical methods to control their quality. Context Heat treatment as a wood modification process is based on chemical degradation of wood polymer by heat transfer. It improves mainly the resistance of wood to decay and provides dimensional stability. These improvements, which come at the expense of a weakening of mechanical properties, have been extensively studied. Since a decade, researches focused mainly on the understanding of wood thermal degradation, on modelling, on quality prediction and quality control. Aims We aimed at reviewing the recent advances about (i) the analytical methods used to control thermal treatment; (ii) the effects on wood decay resistance and (iii) the advantages and drawbacks of a potential industrial use of wood heating. Methods We carried out a literature review of the main industrial methods used to evaluate the conferred wood properties, by thermal treatment. We used papers and reports published between 1970 and 2015, identified in the web of science data base.. Results Approximately 100 papers mostly published after 2000 were retrieved. They concentrated on: (i) wood mass loss due to thermal degradation determination, (ii) spectroscopic analyses of wood properties, (iii) colour measurements, (iv) chemical composition, (v) non-destructive mechanical assessments and (vi) use of industrial data. Conclusions One of most interesting property of heat-treated wood remains its decay resistance. Durability test with modified wood in laboratory are expensive and time-consuming. This review displays data from different analytical methods, such as spectroscopy, thermogravimetry, chemical analyses or mechanical tests that have the potential to be valuable indicators to assess the durability of heat treated wood at industrial scale. However, each method has its limits and drawbacks, such as the required investment for the equipment, reliability and accuracy of the results and ease of use at industrial scale.

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The potential of colour measurement for strength prediction of thermally treated wood

Cited by 109 publications

References 2 publications

Mechanical properties of heat-treated wooden material utilized in the construction of outdoor sitting furniture

Mechanical properties of heat-treated wooden material utilized in the construction of outdoor sitting furniture

Changes in chemistry, color, dimensional stability and fungal resistance of Pinus radiata D. Don wood with oil heat-treatment

Control of wood thermal treatment and its effects on decay resistance: a review

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