On the relationship between the shear forces in human skin and the grain direction of woven fabric

Chapter 4.1

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The prevalent utilisation of the grain line vertically in pattern cutting is arguably connected to the tailoring matrix, the theoretical approximation of the body that is derived from horizontal and vertical measurements of the body in an upright position. As woven fabric generally is anisotropic i.e. rigid on the straight grain and flexible on the bias this utilisation lack of dynamic qualities in interaction with the moving body.

Langer’s lines utilised in surgery denote the skins anisotropic qualities and is thus also a notation of the movements of the body. Through concrete experiments by cutting and draping fabrics on live models guided by Langer’s lines this research explores and defines possible congruence’s between the shear forces of human skin and the anisotropic qualities of woven fabric. Suggesting, through a number of garment prototypes, how the utilisation of fabric grain may shift across the body.

The most common use of the direction of fabric grain in garment construction is arguably strongly connected to the paradigm of the tailoring matrix. Because of the construction of weft and warp, few woven fabrics are isotropic – they behave the same in all directions – but instead are generally anisotropic – they behave differently in different directions (Gordon, 1981:251). In garment construction it is typical to ‘cut on the square’ – to place the grain line vertically in relation to the body so as to minimise stretch and distortion (cf. Efrat, 1982:55) – or alternatively to cut ‘on the bias’ – to cut diagonally to grain, as introduced by Vionnet in the 1920s (cf. Kirke, 1998; Bunka Fashion College, 2002) – to take advantage of the fabric’s elastic qualities and to different drapes or falls that emerge when cutting the fabric on the bias.

Langers lines

Langer’s lines (Langer, 1861), a model used in surgery, denote the anisotropic qualities of the human skin. Along the lines the skin is less flexible and across the lines it has more flexible qualities, thus Langer’s line may also be used as a notation of the movement scheme of the body. The directions of Langer’s lines change across the body as does the amount of flexibility in the skin. The anisotropic qualities of woven fabric, its rigidity on the straight grain and its elasticity on the bias, contain a latent aesthetic potential when considering the fabric’s relation to the movement of the body as shown in Langer’s lines. ­The anisotropic qualities of woven fabrics contains a latent aesthetic potential, both functional and expressional, if garments are constructed in a manner where the direction of the fabric is considered in congruence with Langer’s lines. When employing the kinetic garment construction framework and the way that the fabric around the body according to this theory, the grain direction shifts over the garment.

Langers lines with Kinetic Garment Construction framework

The garment prototypes in the next chapter explores and defines a number of connections between shear forces in the skin, bodily movements and anisotropic fabric qualities, proposing how the utilisation of fabric grain may shift across a garment in congruence with the movement of the body and thus opens up for new unseen expressional and functional values in garment construction. As such the 'Kinetic Construction Theory' is a general theory and can form, just as the traditio­nal tailoring matrix does, the foundation for any kind of dress, standardized or customized.

Analysis of two of these experiments, a pair of trousers and a chemise, explores and visualises  congruence’s between the elastic qualities of the skin and the bias of the woven fabric. The visual analysis exposes the directions of the straight grain, the cross grain and the bias of the fabric on top of Langer’s lines together with the directions from the kinetic garment construction theory, and shows correlation between the elasticity of the skin across Langer's lines and the elasticity of the woven fabric along the bias of the fabric.

[Trousers on Langers 3D man + pattern with checks]

[Chemise on Langers 3D man + pattern with checks]

This visualised correlation calls for further studies and experiments that explore and define possible models and methods clarifying and taking advantage of possible connections between shear forces in the skin, bodily movements and anisotropic fabric qualities.

The research projects Function Wear[1] and Roll to Bag[2] explored such functional possibilities and potentials of the kinetic garment construction framework, as well as practical aspects as potential benefits and problems in industrial production settings.

One such functional potential is clearly visible when a similar analysis is made on the hard-shell jacket in chapter 5. The Gore-Tex fabric used for the jacket has no stretch properties along the warp or the weft but can med stretched out 5% on the bias. For the movement of raising the arms the congruence’s between the skins elasticity and the stretch properties of the fabric on the bias hence enhances the flexibility of the sleeve movement.

Shell jacket on Langers 3D man + pattern with checks

The general fabric directions and seam lines in contemporary fashion are connected to various archetypal garments, and large parts of the fashion design industry today refer to and/or elaborate on these archetypes. The kinetic garment construction – beginning from the structure of the body and the material qualities of the fabric – proposes alternative starting points and hence allows for previously unconsidered developments.

In addition to presenting an alternative theoretical approximation of the body and new methods of constructing garments, the kinetic garment construction theory questions this conventional utilisation of the grain direction of fabric. While wrapping the fabric around the body, the direction of the grain varies (instead of running straight vertically or being on a 45-degree bias) over the garment, creating diverse expressions and functions in different ways across the garment. Arguably, these asymmetrical distortions, addressed by Gordon as “weird and almost certainly unwelcome” instead have a great potential to create enhanced functions and new diverse expressions if applied in a manner congruent with the biomechanical and human kinetic functions. As such, this work contributes to a change of predisposed beliefs regarding use of materials in fashion design, and it may also change the notions of fit that are derived from the tailoring matrix, standards for the positioning of seams, etc.

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