Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2006. / Producing high quality end products, rather than focusing on volume production, is
slowly but surely becoming the main driving force in the wood processing industry of
South Africa. Drying defects such as surface checks and discolouration by yellow
stain and kiln brown stain are major factors in softwood timber downgrades when
selecting furniture grade timber. Previous efforts to control these defects have
focused on schedule adaptation, but as the industry is still mainly concerned with
volume production, and because of the varying lumber price, longer schedules to
control these drying defects have not yet been that attractive for the larger sawmills.
In ongoing research in this laboratory, a dip treatment of freshly sawn softwood boards
in an aqueous solution containing a surfactant called sodium lauryl sulphate (SLS)
was used to try to influence the mechanism involved in the development of these
stains. Further, complementary research is reported in this study. Firstly, the
possibility of using SLS solutions to control surface mould development and bluestain
was investigated. Results showed that SLS did control the development of blue stain
and mould growth in open-stacked boards for up to three weeks, using concentrations
as low as 0.1%, and up to two weeks in closed-stacked timber when using
concentrations of 0.2%.
Secondly, it was investigated whether SLS treatment would have a detrimental effect
on downstream product quality; in particular, kiln dried boards and glued components
for furniture manufacturing. Since SLS influenced fluid water flow during kiln drying,
the treatment could have exacerbated the occurrence of surface checking due to
altered moisture distribution profiles. Results of this investigation showed that the SLS
treatment did not result in increased surface checking.
Thirdly, as furniture quality timber treated with SLS would be glued, (and also finished
with surface coatings), it was further considered important to determine if SLS
treatment influenced adhesion properties of wood surfaces. Based on shear test
results, it was established that SLS did not influence the adhesion properties of wood
when glued with two most commonly used glues in the furniture industry i.e. polyvinyl
acetate (PVAc) and urea formaldehyde (UF).
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2003 |
| Date | 3 1900 |
| Creators | Perold, Maurits |
| Contributors | Rypstra, T., Scheepers, G. C., University of Stellenbosch. Faculty of Agrisciences. Dept. of Forest and Wood Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 976295 bytes, application/pdf |
| Rights | University of Stellenbosch |
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