Sunday, November 29, 2009

Problems with fit

The concept of shoe fit is largely a subjective one. Size alone is not the only determining factor. Research from the Battelle Memorial Institute has shown there are at least 38 individual factors influencing or involved in shoe fit. Many of the 38 factors were subjective involving the opinion and attitudes of consumer and fitter alike. In the end it was the customer who determined whether the shoe fitted or not.

Asymmetry and anatomical variation mean many people are challenged when seeking an ideal fit. Both style and pattern of a shoe bear influence on sizing and fit is determined by the distribution of foot mass within the shoe. Heel height and toe spring are critical for functionality. Shoe types such as fashion footwear and work boots may be fitted with a bit more volume allowance than the slightly snugger fit of an elegant fashion or dress shoe. The type of shoe construction can bare an influence. e.g. welts, cements, slip lasted, stitchdown, injection-moulded etc, will show slight differences in fit on the foot. Some manufacturers or brands apply their own particular specifications of dimensions on their lasts e.g. backpart, forepart, tread, etc. and this makes a difference in fit among different brands on a given size. The foot fitted in the morning will be smaller than the foot fitted in the afternoon. Toe shape of the shoe may influence the fit. Shoes with narrower toes may need to be worn a half size longer (when available).

Further Reading
Belanger R 1997 Big black boots: how to pick the right size
Byrne M Curran MJ 1998 The development and use of a footwear assessment score in comparing the fit of children's shoes The Foot 8 215-218.
Ceeny E The form of the foot in relation to footwear The Chiropodist 304-311.
Foot Fitter Genovation
Gardener R 1856 The illustrated handbook of the foot London
Ledger FE 1985 Put your foot down: A treatise on the history of shoes Melksham: Coin Velton.
Manning JR 1966 Size standardisation: Europoint The Chiropodist 21:6 187-200.
Mondopoint: A metric system of shoe sizing and marking Australian Podiatrist August 1976 102-103.

Friday, November 13, 2009

Shoe width fitting

According to Rossi (2000, p.202) standard width fittings were introduced in 1880. The ball width on the last determines ball width on the shoe. This measurement is not a linear side to side measurement across the foot but instead the girth which captures the volume of the forefoot. Several standard and width fittings are available in the UK size system to accommodate differences in three-dimensional girth. In women's shoes, A is the narrowest and G the widest. For children the range is A to H; and for men it is from 1-8. The girth increase between fittings is normally 6.5mm (one fourth of an inch). Most lines are only available in one size usually women's D and men's 4. The girth around the ball of the foot of the foot increases by 5mm for whole sizes up to children's size 101/2 and 6.5mm for whole sizes above this. In the American system it is two less, eg AAA is the equivalent to the UK A. There is no equivalent Continental width fitting system and the shoes are generally narrower than in the UK. In the American (or Standard) System the first number in the code represents the width (1 = A, 2 = B) The second number followed by a zero denotes the whole size: when the second number is followed by a 5 it indicates a half size. In the American (Arithmetic standard width measurement) this ranges from AAAAA to EEEEEE.

Rossi W A (ed) 2000 The complete footwear dictionary (2nd ed) Kreiger Publishing Co. Florida.

Monday, November 2, 2009

Methods of Shoe Construction

There are many ways to attach the sole to the upper but only a few methods are used in mass production. Shoes were traditionally made by moulding leather to a wooden last. Modern technology has introduced new materials and mechanised much of the manufacture. Remarkable as it may seem the manufacture of shoes remains fairly labour intensive. No matter the type of construction the first stage in construction is to attach the insole to the under surface of the last. Two main operations follow: Lasting describes when the upper sections are shaped to the last and insole. Followed by Bottoming, where the sole is attached to the upper. The process of bottoming will determine price, quality and performance of the shoe.

Cement Construction (also known as 'Stuck on construction' in the UK; or the 'Compo Process’) is used for lightweight and flexible shoes and the outsole is stuck to the upper by adhesive. Bonwelt is another variation with its distinguishing feature being a strip of welting attached by stitching or cementing to the top edge of the insole. The shoe is then flat lasted. This is not a true welt construction wherein the welt is attached to the rib of the insole.

Goodyear Welt is used for high quality dress and town shoes, the top section (or welt) is chain stitched to the upper and insole rib at the point where it curves under the last. This is supplemented by a lockstitch out seam bonding the welt and outsole. The outsole is then sewn to the welt around the edge. Goodyear Welt creates heavier less flexible footwear and the process is regarded as the sturdiest of all shoe constructions.

Stitchdown (also known as Veldt or veldschoen) is a cheaper method used to produce lightweight flexible soles for children's shoes and some casual footwear. Here the upper turned out (flanged) at the edge of the last and stitched to the runner. In some countries it is known as 'veldt' and 'veldtschoen.' The technique is used for lower priced footwear.

Mocassin is considered to be the oldest shoe construction this consists of a single layer section, which forms the insole, vamp and quarters. The piece is moulded upwards from the under surface of the last. An apron is then stitched to the gathered edges of the vamp and the sole is stitched to the base of the shoe. This method is used for flexible fashion footwear. The imitation moccasin has a visual appearance of a moccasin but does not have the wrap around construction of the genuine moccasin.

Moulded Methods have the lasted upper placed in a mould and the sole formed around it by injecting liquid synthetic soling material (PVC, urethane). Alternatively, the sole may be vulcanised by converting uncured rubber into a stable compound by heat and pressure. When the materials in the moulds cool the sole-upper bonding is complete. These methods combine the upper permanently into the sole and such shoes cannot therefore be repaired easily. Moulded methods can be used to make most types of footwear.

Force Lasting (also known as Strobel-stitched method or sew in sock) has evolved from sport shoes but is increasingly used in other footwear. The Strobel-stitched method (or sew in sock) describes one of many force lasting techniques. The upper is sewn directly to a sock by means of an overlooking machine (Strobel stitcher). The upper is then pulled (force lasted) onto a last or moulding foot. Unit soles with raised walls or moulded soles are attached to completely cover the seam. This technique is sometimes known as the Californian process or slip lasting.