An investigation into the suitability of selected lesser utilised Ghanaian hardwoods for use as outdoor furniture and decking

Opoku, Francis Yaw (2007) An investigation into the suitability of selected lesser utilised Ghanaian hardwoods for use as outdoor furniture and decking. thesis.

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Abstract

The potential for using the Ghanaian lesser utilised hardwoods esa (Celtis mildbraedii), denya (Cylicodiscus gabunensis) and dahoma (Piptadeniastrum africana) for garden furniture and decking in the UK is investigated. Specific properties are examined using field and laboratory experiments against reference species; iroko (Milicia excelsa), African mahogany (Khaya ivorensis), teak (Tectona grandis) and European oak (Quercus robur). The effectiveness of decking and teak oil coatings at reducing weathering defects is described. With weathering colours of all species changed over the six month exposure period though the greatest rate of change is seen in iroko and oak. There is an increase in lightness (L* value) and greying (a* and b* values). Oil treatments delay the rate of colour change but do not prevent it. Oil treatments reduce checking during weathering which is worse in oak, esa and denya. Analysis of samples during outdoor exposure using FTIR show a loss in lignin at the surface, with the absorbance peak at (1505cm)-1 absent following 1 month for untreated samples and two months for oiled samples. Scanning electron microscopy revealed that teak and deck oil formed thin films on the surfaces of wood but do not coat vessel lumens. Following six months exposure a number of defects were apparent, including raised wood fibres, fungal colonisation and cell wall and pit checking. Defects are observed in coated and uncoated wood. Natural durability using the method described in BS EN 350-1 show denya to be very durable, dahoma moderately durable and esa not durable. Field exposure shows esa is liable to blue stain in service though no decay is detected in lap joints after nine months exposure.

Item Type: Thesis
Keywords: hardwood, Ghana, outdoor furniture, decking, furniture, wood
Depositing User: Elizabeth Chamberlain
Date Deposited: 21 Oct 2008 13:29
Last Modified: 08 May 2014 10:01
URI: http://hdl.handle.net/10239/134

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