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The effect of solar radiation on the surface checking of lodgepole pine Urban, Kathrin
Abstract
The weathering of wood is caused by a complex combination of chemical and mechanical effects. One of the first signs of weathering is the development of checks at wood surfaces. This study examined the effect of UV-B, UV-A, visible light and infrared light on the development of checks at the surface of lodgepole pine {Pinus contorta Dougl. ex Loud.) deck boards for three periods of twelve weeks, each starting in June 2004. Colour change and change in lignin content were analysed during exposure. A separate experiment examined the loss of weight and tensile strength of microveneers clamped together during exposure. SEM images provided information about structural changes. UV-B had the most significant effect on the quantity, total width, total length and total area of checks that developed at the surface of boards during exterior exposure. UV-B degraded lignin and there was a darkening and reddening of the exposed surface. Defibration of the cell structure at the microscopic level was also observed. UV-A and visible light degraded the surface to a lesser extent. Photodegradation was a surface phenomenon with UV-B only affecting the two upper layers of the veneer blocks (150 um). It can be concluded that selectively protecting wood from UV-B, UV-A and visible light using chemical means might result in less severe checking of lodgepole pine during weathering. Even the blockage of UV-B alone might lead to significantly improved behaviour of surfaces, when the natural look of decks is preferred.
Item Metadata
Title |
The effect of solar radiation on the surface checking of lodgepole pine
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2005
|
Description |
The weathering of wood is caused by a complex combination of chemical and mechanical
effects. One of the first signs of weathering is the development of checks at wood surfaces.
This study examined the effect of UV-B, UV-A, visible light and infrared light on the
development of checks at the surface of lodgepole pine {Pinus contorta Dougl. ex Loud.)
deck boards for three periods of twelve weeks, each starting in June 2004. Colour change
and change in lignin content were analysed during exposure. A separate experiment
examined the loss of weight and tensile strength of microveneers clamped together during
exposure. SEM images provided information about structural changes.
UV-B had the most significant effect on the quantity, total width, total length and total area
of checks that developed at the surface of boards during exterior exposure. UV-B degraded
lignin and there was a darkening and reddening of the exposed surface. Defibration of the
cell structure at the microscopic level was also observed. UV-A and visible light degraded
the surface to a lesser extent. Photodegradation was a surface phenomenon with UV-B only
affecting the two upper layers of the veneer blocks (150 um).
It can be concluded that selectively protecting wood from UV-B, UV-A and visible light
using chemical means might result in less severe checking of lodgepole pine during
weathering. Even the blockage of UV-B alone might lead to significantly improved
behaviour of surfaces, when the natural look of decks is preferred.
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Genre | |
Type | |
Language |
eng
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Date Available |
2009-12-16
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0075075
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2005-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.