Improving the Performance of Clear Coatings on Wood through the Aggregation of Marginal Gains

Evans, Philip D.; Vollmer, Stephan; Kim, Joseph Doh Wook; Chan, George L.; Gibson, Sara Kraushaar

doi:10.3390/coatings6040066

Cited by 25 publications

(25 citation statements)

References 28 publications

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“…Boards were cross-cut using a chop-saw (Omga T55-300, OMGA Industries Inc., South Bend, IN, USA) to remove two 100 mm long pieces from the ends of each board that were not tested during machine stress-grading. These pieces provided specimens whose densities and ring widths were measured, as described previously [24,25], (Table 1). Table 1.…”

Section: Materials and Machining Of Deck Boardsmentioning

confidence: 99%

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Digital Image Correlation of Strains at Profiled Wood Surfaces Exposed to Wetting and Drying

2018

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Abstract:We hypothesize that machining grooves and ridges into the surface of radiata pine deck boards will change the pattern of strains that develop when profiled boards are exposed to wetting and drying. Two wavy profiles were tested, and flat unprofiled boards acted as controls. Full-field surface strain data was collected using digital image correlation. Strains varied across the surface of both flat and profiled boards during wetting and drying. Profiling fundamentally changed surface strain patterns; strain maxima and minima developed in the profile ridges and grooves during wetting, respectively, but this pattern of strains reversed during drying. Such a pronounced reversal of strains was not observed when flat boards were exposed to wetting and drying, although there was a shift towards negative strains when flat boards were dried. We conclude that profiling changes surface strain distribution in deck boards exposed to wetting and drying, and causes high strains to develop in the grooves of profiled boards. These findings help explain why checks in profiled deck boards are mainly confined to profile grooves where they are difficult to see, and the commercial success of profiling at reducing the negative effects of checking on the appearance of wood decking.

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Section: Materials and Machining Of Deck Boardsmentioning

confidence: 99%

“…Basic density and growth ring widths of specimens cut from parent radiata pine boards that were converted into profiled and flat deck board samples. 1 Density measured by water-displacement/oven drying method [24,25]. Standard deviation in brackets.…”

Section: Materials and Machining Of Deck Boardsmentioning

confidence: 99%

Digital Image Correlation of Strains at Profiled Wood Surfaces Exposed to Wetting and Drying

2018

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“…The growth rate and grain angle of each amabilis fir sample were measured using a ruler and protractor, as described previously [15,22]. The densities of separate matched wood samples were measured by water-displacement and oven-drying overnight at 105 ± 5 • C. The average growth rates, densities and grain angles of the amabilis fir samples were: Growth rate = 20 growth rings per cm (Max = 30; Min = 8; STDev = 9.4); Density = 0.38 g/cm 3 (Max = 0.41; Min = 0.33; STDev = 0.028; Grain angle (degrees) = 1.18 (Max = 1.5; Min = 0.3; STDev = 0.56).…”

Section: Characterization Of Profiled Decking Boards and Outdoor Weatmentioning

confidence: 99%

Manufacture of Profiled Amabilis Fir Deckboards with Reduced Susceptibility to Surface Checking

Cheng

Evans

2018

JMMP

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Machining grooves and ridges (peaks) into the surface of wooden deckboards reduces undesirable checking that develops when "profiled" boards are exposed to the weather. We aim to develop improved profiles for amabilis fir decking to reduce its susceptibility to checking, and also to examine whether profiling influences distortion (cupping) of deckboards. We systematically varied radii of grooves and peaks, and the heights and widths of peaks in profiled deckboards, exposed them to the weather, and measured checking and cupping of boards. Profiling significantly reduced the numbers and sizes of checks in amabilis fir deckboards, but increased cupping. Profiles with narrow grooves and tall peaks were generally better at restricting checking than profiles with wide grooves and shorter peaks. Our results suggest that one of the profiles we tested would be better at restricting checking than profiles used previously to manufacture profiled decking from amabilis fir. We conclude that the surface checking of profiled amabilis fir decking can be significantly reduced by altering the geometry of surface profiles. In principal, the same approach could be used with other softwood species that have potential to capture a share of the large and important market for wood decking.

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“…Grain raising was calculated as the difference in roughness of sanded samples before and after wetting and drying. Analysis of variance for a randomized block design was used to examine the effect of grit size on grain raising of samples [20]. Wood samples sanded with different abrasive papers, before and after wetting and drying, were also examined as above using a field emission scanning electron microscope (Hitachi S-4700, Hitachi Ltd, Tokyo, Japan).…”

Section: Effects Of Abrasive Size On Grain Raising Of Maple Panelsmentioning

confidence: 99%

Microstructure and Mechanism of Grain Raising in Wood

et al. 2017

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Grain raising, the lifting of fibres when water is applied to wood surfaces, is a reason why some companies are reluctant to finish wood products with water-borne coatings. However, the elements that lift-up and cause grain raising have not been identified, and the relationship between wood density and grain raising has not been clarified. Our work sought answers to both questions. We planed or sanded different woods using aluminum oxide abrasive paper, and characterized surfaces using profilometry and SEM. Surfaces were re-characterized after wetting and drying. Grain raising is inversely related to wood density. In particular, very low-density woods are highly susceptible to grain raising, whereas grain raising does not occur in high-density woods or planed woods. In low-density woods, sanding tears cell walls creating loosely-bonded slivers of wood that project from surfaces, particularly after wetting and drying. This mechanism for grain raising was confirmed by modelling the action of abrasives on wood cell walls using an array of hollow tubes and a serrated tool. Less commonly, fibres and fibre-bundles project from surfaces. We observed that grain raising was correlated with the coarseness of the abrasive and conclude that it can be reduced in severity by tailoring sanding to account for the density and surface microstructure of wood.

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Improving the Performance of Clear Coatings on Wood through the Aggregation of Marginal Gains

Cited by 25 publications

References 28 publications

Digital Image Correlation of Strains at Profiled Wood Surfaces Exposed to Wetting and Drying

Digital Image Correlation of Strains at Profiled Wood Surfaces Exposed to Wetting and Drying

Manufacture of Profiled Amabilis Fir Deckboards with Reduced Susceptibility to Surface Checking

Microstructure and Mechanism of Grain Raising in Wood

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