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Back to the Corsetry-1 page.   Robin Whittle 19 August 2001


An Engineering Miracle

From Science and Mechanics, February, 1964

By Edward Nanas

There is more to brassiere design than meets the eye. In many respects, the challenge of enclosing and supporting a semi-solid mass of variable volume and shape, plus its adjacent mirror image-together they equal the female bosom-involves a design effort comparable to that of building a bridge or a cantilevered skyscraper.

Bra designers must solve the problem of providing an uplift against vertical (downward) and sometimes tangential forces. They have borrowed from the design of suspension bridges, supplying vertical supports of wire or bone that are similar to a bridge's piers. Wire cages for the cups duplicate wire ropes supporting the bridge's roadway.


Hundreds of bra designers, many with engineering training, eagerly accept this challenge and apply their unusual skills eight hours a day, five days a week. The center of this activity is a five-block stretch of sky-scrapers flanking Manhattan's Madison Avenue in the shadow of the Empire State Building. More than 200 brassiere design innovations are sent to the United States Patent Office each year from this area.

 Why so many patent applications on brassieres? More than $450 million is spent annually on brassieres in this country alone. How much of this cash a bra will attract is a direct result of how well it does it job. And its performance, of course, depends upon its design. By the 1930's, women had secured a certain measure of equality with men and fell they could relax a bit. Their dresses were designed to the natural female form, which meant that women, after having been flattened for the decade following World War I, began looking for something that would help them fill out the front of their dresses. So the uplift bra was invented.

 At first, the uplift consisted only of a cotton band stretched across the torso beneath the bosom. It was called the "bandeaux." Later, to reduce the obvious visual effect of lateral and vertical motion, and to provide firmer support, breast cups were added and held up with shoulder straps.

 To form a basic breast cup all it takes is two curved pieces of material sewn together along the curve. The resulting container will approximate a hemisphere or a cone, depending upon the sharpness of the curve. The resulting seam, under pressure, often proved irritating to the wearer. Hence the evolution of cup design has centered to a large degree on getting the seams out of the way of sensitive areas. Cups are now frequently designed in multi-sections which, when properly pieced together, produce a form-fitting hemisphere or cone. The cup may be made up of four to eight triangles and other quadrilateral sections in mixed combination.

 Bra sizes have been standardized somewhat over the years, although bras of the same nominal size will differ in terms of comfort form-fit, support, construction, durability and price. There are two basic measures used to characterize a brassiere's size. Inches indicate the basic size, while alphabetical designations denote variations in the volume the bust cup.

 Most brassiere designers work only with "ideal" model size, which happens to be 34-B. To arrive at tooling requirements for other sizes, they extrapolate. Commercial sizes range from 28-AAA to 55-DD. The 34-B "ideal" is not entirely an arbitrary designation. Rather, it represents the bustline considered most pleasing to the artistic eye of most dress designers-although there is room here for disagreement.

 Bra size, contrary to popular belief, is measured with a tape measure initially across top of the chest, not across the bust. If this measure is 34 inches, the bra size is 34.

 There are several ways to make a volumetric determination of cup size. If the bust is considered essentially a half-sphere, the designer may use any of the following formulas to determine the volume of the breast cup:

where V equals the volume of one-half sphere, D equals the diameter of the sphere, and r equals the radius of the sphere.

 If the bust is conical, the formula which may be used is:

where Db equals diameter of the cone's base and h equals the height of the cone.

 One can readily see that it might be rather difficult to measure accurately some of the variables, especially if the individual bust exhibits more fluidity than rigidity. Therefore, designers prefer to make initial volumetric determinations experimentally on live models with firm busts. The customer is told to determine her individual bust size by measuring the number of inches around the top of the chest, then measuring the girth across the highest part of the bust. If the difference between the two measurements is 1 inch, the cup size would be A; 2 inches, B; 3 inches, C; 4 inches, D.

 To achieve support, designers must consider ways to provide an uplift against the vertical (downward) and sometimes tangential force of the woman's bust. This force, of course, is due to gravity. The object of the designer then is to keep the bosom at a pleasing equilibrium in the face of gravity.

 There are a number of methods of achieving bust equilibrium. First and most obvious is the addition of straps to the top of the breast cups. However, this solves only part of the problem since the weight of the bosom often is more than the straps can sustain without cutting uncomfortably into the wearer's shoulders.

 So the lower contour of the breast cups usually are attached to a wide band which completely encircles the torso and latches (by means of hooks and eyes) at the back. The skin-tight band tends to provide a firm anchor beneath the bosom-a horizontal plane below which the bosom cannot slip. To meet expansion characteristics of the rib cage, the band may contain expandable rubberized sections and elastic gussets at points where excess pressure might cause the wearer discomfort. These gussets serve similar functions to the expansion joints in bridges and ships.

 Where larger cup sizes are required, the above measures still might not be enough to offset the downward vertical force of the bosom. Additional uplift support is then provided by sandwiching various rigid or semi-rigid structural members between the layers of material that make up the breast cup. The structural members may consist of (1) starched or plasticized material; (2) vertical, curved or tangential wire forms, or (3) bones and chicken feathers.

 The structural members act much like shoring timbers used in coal mines except that the retaining member is angled down and in against the rib cage rather than out and away. Because they are secured at both top and bottom of the cup, they act as segments of a retaining wall.

 Another method of offsetting the downward force of the bosom - and restraining undesirable lateral movement of the semi-fluid masses - is exemplified in the design of the "Action" bra. This bra employs the principles of cantilever suspension, setting up a situation involving opposite and equal vector forces. Extending from each shoulder strap is an S-shaped strap which runs across the top of the breast cup and down to the central point between the two cups, then underneath and up the outside edge of the opposite cup.

 In effect, a figure 8 is created which behaves in cantilever fashion. Part of the downward vertical force on one breast acts in conjunction with that of the other, partially canceling it - that is, converting the downward force into a restricted horizontal or diagonal force equal and opposite instead of in parallel.

 Within these basic designs there are virtually unlimited engineering combinations. The Lovable Co., which ships more than a quarter of a million bras each week, has developed a simple device called the T-strap. This strap is affixed to the cup with a small T-shaped fastener at the end instead of being sewn to the cup. Along the top, inside contour of each cup are small, evenly-spaced holes (six in all) into which the metal devices may be inserted. Thus the strap may be secured anywhere along the top of the bra, either to provide a more comfortable vector angle, or to make the strap conform to the angle of the dress straps so that the bra straps do not peek out.

 Undoubtedly, the most impressive challenge comes in the design of a strapless bra. Since the cable-type support of shoulder straps is not available, all uplift must be provided from the bottom, often without the security of a straight-around skin-tight band.

 The problem is generally solved by fabricating a wire cage for the breast cup, with a heavy, semi-circular wire running under each cup. This double-U, with additional vertical supports imbedded in the lower band, resembles a suspension bridge. The structural principles are almost identical.

 Arthur Garson, who has been designing brassieres for 35 years, recently was awarded a patent on a completely self-supporting strapless bra that does not require auxiliary supporting means such as uncomfortable wires or bones in the breast cup. To accomplish this feat, Mr. Garson departed somewhat from conventional materials practice in that he uses plastic in his design. Plastics are rarely used in place of wires and bones because those that resist the heat of the wearer's body generally are too costly for mass production.

SHOWN HERE is patent 3,030,962 for a strapless bra, issued to Arthur Garson, president of Lovable Co., and an experienced bra designer. More than 200 innovations in brassiere design are submitted to the Patent Office annually.


Sandwiched into the outer triangular sections of the new strapless cup are curved and flexible plastic stiffening members, shaped to conform to the conical side portions of the cup. These impart rigidity and upright self-supporting characteristics to the cup. The cup itself is made of a stiff but flexible material which cooperates with the laterally-spaced plastic members to impart additional support.

 The quest for new and different methods of enclosing the bosom goes on at a fever pitch. New markets are constantly being explored, and new markets mean new designs. One Madison Avenue designer, an engineer by training, is convinced that he can apply the aerosol principle to the brassiere. He has developed a quick-hardening plastic compound which he intends to spray on a perfectly form-fitting plastic bra - one that can be peeled off at the end of the day. However, one major problem remains. He has not yet found a satisfactory method containing the bust in the proper configuration while the liquid bra is being sprayed on.

 Brassiere design is one engineering active activity, at least, in which the United States is ahead of the Soviet Union. The Russians are about 30 years behind, according to Mrs. Ida Rosenthal, 77-year-old matriarch of the American foundation industry and head of Maidenform, Inc. She recently returned from a tour of the Soviet garment industry and found that bra designers on the other side of the Iron Curtain have not yet discovered stretch fabrics, foam padding, hooks and eyes, or the strapless bra.

 Meanwhile, the Americans are forging ahead and may soon get a breakthrough that will provide a spray-on brassiere in an aerosol can.