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Experimental method: By measuring the load required to lift the bra strap from the skin over a known surface area and by applying Newton's 3rd Law, the corresponding pressure on the skin was calculated. A series of transducers was constructed each having a surface area of 20 x 4 mm. These were attached to the selected areas of the bra, a light support, 38C, non-underwired bra manufactured by Sloggi. The transducers were constructed from velcro, one side of which was fixed to the selected area of the bra with double sided pressure sensitive adhesive assuring a high level of adhesion at this interface. A straight 'pull' to a point on the top surface of the velcro would have made it very difficult, or impossible, to determine the actual loaded area because the transducer would be lacking in rigidity. The transducer was therefore stiffened with a 1inch (25mm) long safety pin attached to the top layer of the velcro. In this way, although the actual velcro surface area was somewhat larger than 20 x 4mm, an 'effective' load area of 20 x 4mm was accurately defined. It was then possible to visually estimate when the stiff area of the transducer had fully parted the bra strap from the skin under the area of the transducer. This technique also allows some flexibility of the transducer, which is required to follow the curvature of the body sections, whilst at the same time allowing a true lifting area to be defined. The measurements were made on the tautest (tightest) regions of the bra, that is the elasticated seams around the edges of the bra and the straps themselves. The actual cups were stretchy and exerted a very low compression on the breast, when compared with the straps. The bra was put on and the load required to lift the complete section from the skin was measured. 2 measurements from each area were taken and the mean value calculated with an estimate of the variation. The resulting force in Newtons was converted to pressure by using the formula: Pressure, P = Force,F / Area,A where P is in Newtons per mm2, F is in Newtons and A is in mm2. To Results |