Opening the SATRA Bulletin archives

An opportunity to examine the working lives of our shoemaking predecessors in past decades.

SATRA Bulletin has been published continuously since 1935, with the purpose of providing valuable technical and newsworthy information to companies working in the footwear and leather industries. Starting with this issue, we will occasionally delve into SATRA’s publication archives to re-visit published articles that provide a fascinating insight to technologies and construction methods used by previous generations of shoemakers. To begin with, we head back to the 1941 – at the height of World War II – to investigate the growing use of a new footwear material… plastic.

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From the Monthly Bulletin of the British Boot, Shoe & Allied Trades’ Research Association - April 1941

Plastics

Of all industrial and scientific developments which have marked the past ten to 20 years, that of the employment of plastic materials in industry is undoubtedly one of the most significant. To those who give the matter only a passing thought, the term ‘Plastics’ brings to mind the moulded wireless cabinet, telephone instrument, pipe rack or some similar object which encounters the eye in the home; but the development has travelled far beyond this stage and there is now hardly one major industry which does not employ plastic materials in one form or other and it is fairly safe to say that the near future will see a rapid extension of this development. In this movement the shoe manufacturing industry is going to be deeply concerned and although the present times may not be propitious in this country for new departures there are other countries not similarly handicapped. We in Great Britain must think to the future and be prepared again to enter the world markets with methods and ideas which are, at the very least, in line with our competitors.

When thinking of plastics it is as well to get away from the one idea as exemplified by the well known Bakelite. Such a wide variety of materials both rigid and flexible are made from synthetic plastics that even a sketchy list would be too lengthy for this Bulletin, but they range from the finest fabrics to machinery parts which can outlast the toughest metals, with a multitude of variation in between. Being man-made products they can be made to possess a great number of features which render them outstandingly advantageous for many purposes and, greatest of all, their adaptability to mass production methods can so reduce production costs as to make their adoption in many instances an economic certainty.

What are these plastics? Perhaps the earliest known plastic was celluloid but from this crude beginning has grown up a wide range of organic compounds derived in the main from such things as coal, wood, petroleum, flesh and other forms of carbonaceous matter. These are generally reduced to forms of synthetic resin powders or sheets which can be moulded to definite and permanent forms by heat and pressure in a variety of methods. The technique of these latter processes has advanced with great rapidity and nowadays it is possible to produce by one operation an article which is finished in every degree, moulded, coloured and polished. If a similar article were to be produced from wood or metal there would have to be a series of operations to produce a similar result and also a great deal of cutting to waste perhaps. In plastic moulding there is no waste.

A recent publication [Plastics in Industry by ‘Plastes’ – Chapman & Hull Ltd], written specially for the attention of industrialists, admirably surveys the whole field of production and employment of plastics. The authors hope that ‘many confused ideas regarding plastics and the plastics industry will be clarified and that there will be presented to the eyes of the aforementioned industrialists a comparatively new series of materials of construction worthy of their examination and, finally, worthy of their employment for series of mass production.’

There is much of interest to learn from this book regarding the use of plastics in many industries and we quote below that section which deals with the footwear industry. To those who read the book it will become obvious that if there is not a great increase in the employment of plastics in shoe construction and processing it will probably be due to inertia in the trade itself, a state of affairs which may not exist amongst our wide awake competitors.

Footwear

‘It is surprising the number of uses now being found for plastics in the shoe trade, some of which are only seasonable novelties of no permanent value, whilst others are of considerable importance. One of the most interesting of recent applications is the moulded Pearsonite heel sold by Pearson Heel Manufacturing Co., St. Louis, Mo., and moulded of Texolite by the plastics Department of General Electric Co., Pittsfield, Mass. This new type of heel will not split, peel, crack or separate from the shoe and can be attached with the same standard machinery. Because of the flexibility and toughness of the material, nails guided into holes of the interior honeycomb construction become firmly embedded and cannot be pulled out. The bottom of the heel is designed to accommodate a patented Pearson top lift which can be inserted easily. When the lift wears down, it is a simple matter to snap it out and replace it with a new one. This distinctive and yet severely practical plastic non-scuffable heel is available in a wide range of colours to match or contrast with the leather of day-time shoes, while transparent or opaque heels embedded with rhinestones make a glittering ornament for evening slippers. Although, naturally, the Pearsonite heel is more expensive than the standard wooden one, it possesses advantages which render the extra cost fully justified. Incidentally, this moulded heel received one of the principal awards in the Style classification of the Fourth Annual Modern Plastics Competition held by Modern Plastics magazine in 1939.

‘Whilst still on the subject of heels, it is, of course, well known that celluloid is used to provide the wooden heel with a scuffles cover. The celluloid, in the form of a shaped black or coloured sheet 12-15 thou. in., is soaked in methylated spirits until it is thoroughly soft and then forcibly wrapped around the wooden heel or core and allowed to dry. During drying it becomes taut and adheres tenaciously to the wood surface. Celluloid is also used for eyelet holes, lace tips or tags, heel plates and toe puffs. Shoe fillers in paste form also contain plastics and rubber and among the advantages claimed for them over the sheet fillers is the elimination of pre-determined sizes and shapes. Manufactures claim that the new latex cork fillers do not creep, bunch, crumble or permit gutter wells.

‘Celluloid nitrate and, to a limited extent, the new acrylic resins, are used in the finish of leather and textiles in the shoe industry. According to all reports, aqueous dispersions of acrylic resin have quite a future as leather finishes when the price has been reduced to make the new process competitive.

‘Shoe ornaments, such as buckles, clasps, etc., are made of casein, cast resin and cellulose acetate. The first-named plastic is the cheapest, but delightful colour effects are possible by the use of the jewel-like cast resin. Cellulose acetate foil may be formed into flower petals and buds and other decorative shapes. An advantage of casein, which is not found with other types of plastics, is that the surface may easily be dyed by means of an aqueous or alcoholic solution of basic and acid colours.

‘On the operational side of the shoe industry plastics also find several uses. Thus, a new type of shoe pattern made of transparent cellulose acetate edged with metal is now in use in America in place of the opaque fibre pattern. This is called the Da-Lite and is manufactured by J. J. Albrecht & Son, U.S.A. It is claimed that whilst this new transparent pattern fulfils all practical cutting requirements, it enable many worthwhile economies to be made in cutting, as the operator can see exactly what the leather is like under the pattern.

‘The idea of moulding shoe-lasts of a suitable plastic material has captured the imagination of several workers, but so far the difficulties in producing a material strong enough to stand up to the shocks and vibration of working, to take nails as easily as wooden lasts and yet able to be melted and re-cast when worn out, appear, at present, to be unsurmountable. There is no doubt, however, that moulded lasts which could be continually re-used would prove a great boon to the industry and, incidentally, save from waste an enormous tonnage of valuable timber. Old wooden lasts are of no use at all, except as fuel.

‘The plastic suitable for lasts would, obviously have to be a thermo-plastic and it is possible that one of the new lignin plastics might prove suitable. The writers refer particularly to the lignin-sulphur resins which are thermo-plastic and possess reasonable good mechanical properties (degree of elasticity 52,000 kilos. per sq. cm. and modulus of rupture 510-555 kg. per sq. cm.). Such products could be made cheaply from wood waste.’

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Reprinted from SATRA’s Monthly Bulletin, April 1941.

Publishing Data

This article was originally published on page 38 of the May 2015 issue of SATRA Bulletin.

Other articles from this issue »

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