Figure

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Figure is a natural formation in timber, in which the grain of the timber is altered for one reason or another. Such altered grain formation often results in aesthetically pleasing patterns such as fiddleback or flame, burl, mottle, birds-eye, quilting and dimple, to name a few. Each of these figure types may result from different processes.Below are descriptions of our figure grading. Examples are shown for flame but the descriptions can be extrapolated for any figure type.

A Grade

Generally speaking A grade timber has no figure. It is free of blemishes, knots and grain swing. Our A grade timber may have a mild figure through it but will not be enough to categorise as AA grade. As with all blackwood, there will be a large variety of colour, density and growth-ring width.

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AA Grade

Figure mild yet noticeable but may not reach across the entire width of the piece. It may be patchy through some areas and the figure may not have the depth compared with AAA grade.

Image of AA Figure, Image of AA Figure, Image of AA Figure, Image of AA Figure, Image of AA Figure, Image of AA Figure, Image of AA Figure, Image of AA Figure, Image of AA Figure

AAA Grade

Consistent, highly figured timber that is present throughout the piece. Increased depth of figure.

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AAAA Grade / Mastergrade

Extreme figure. Figure depth near maximum for species. Visual throughout entire piece.

Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure, Image of AAAA / Mastergrade Figure

Other

Further examples of figure types in Blackwood can be seen below:

Image of 'Dimple' figure  Image of 'Mottle' figure  Image of 'Quilting' figure

Video

This clip shows light reflection across a flat piece of fiddleback. For best viewing results we recommend upgrading your web browser to the latest version.

Figure formation

From experience in assessing trees for figure, such as flame, we can suggest that it is not directly related to size, age, or environmental conditions such as soil type, rainfall, temperature, elevation and aspect. Although these variables may have some effect on flame formation they are not directly related.

A theory that best explains our experience with Blackwood (Acacia melanoxylon) trees that exhibit flame is that the phenotype of an individual must contain a gene or group of genes responsible for reduced cell wall strength, resulting in compression of the wood (xylem tissue). This may be evident in trees as young as 30-40 years of age and can extend from the roots, up the trunk and out into the branches. This helps to explain why, for example, 50 trees within the same area may display no flame and one individual will have extreme flame.

In combination with a weak cell structure, exposure to an increase in compressive stress due to nearby clearing or disturbance, internal rotting or rotting to one side may also explain, and is common amongst, trees that exhibit flame. The increase in compressive stress as a result of nearby clearing may come about through an increase in above ground biomass as the tree invests more energy into leaves and branches due to increased space and light avaliability. The larger above-ground biomass puts more compressive stress on the trunk of the tree causing it to compress laterally. An increase in stress due to clearing may also be due to the increased effects of wind on stability. Internal rotting or core rotting puts increased stress on the remaining wood, causing it to compress laterally, as would rott occuring in any region that maintains the structural stability of the tree.

Flame formation may therefore develope slowly over the life of the tree (phenotype) or appear relatively suddenly (combination of phenotype and disturbance or rotting). In both formation types, the cambium region is also laterally compressed forming zig-zag patterns when viewed from the outside of the tree (shown below). Further lateral growth of the xylem tissue will therefore result in flame formation.

Image of flame formation

This type of flame is not to be confused with spur/stump flame (ripple effect forming on the spurs of the tree) or branch flame (ripple effect under most older branches), which develope due to the xylem tissue bunching up as it grows outward.

Image of spur flame formation  Image of branch flame formation

Few studies have attemped to explain the processes involved in figure formation but the study by Beals and Davies (1977) helps explain some of the types in further detail:

http://www.aaes.auburn.edu/comm/pubs/bulletins/figureinwood/index.php