Wilson Yarn Clearer

The Wilson Yarn Clearer is a device whose invention improved the quality of spun yarn and hence of the cloth made from it.

The yarn from a number of spinning bobbins, called cops, is wound on to larger packages called cones for subsequent processing into fabric. During the winding of yarn it was traditionally passed through the narrow slit in a steel plate of a yarn clearer or slub-catcher. The object was to catch thick places, or slubs, which occurred when the spinning process suffered an aberration, and to prevent them being woven into the fabric to present unsightly faults. These obviously degraded the appearance of the fabric and of any garment made from it.

In the early 1950s Peter Wilson, a young physicist working at William Hollins Pleasley Vale yarn production factory, became interested in the yarn clearing process.

The occurrence of many slubs in the yarn was well known to the weavers in the Hollins factory in Glasgow for they knew that much labor had to be spent after the weaving on “burling and mending” of the fabric in order to remove as many faults as possible. But in the spinning mill at Pleasley Vale yarn clearing was regarded as an undesirable and costly process. The yarn production people in Pleasley believed that their slub catchers were effective - it was obvious to them that a slub up to an eighth in diameter could not pass through a slot only 10 thousandths of an inch wide. They never saw the evidence of their erroneous belief since they did not see the woven fabric with the many slubs that had passed through their yarn cleaners.

Peter Wilson realized that the true cost of the defective yarn clearing which was currently being practiced warranted the development of a better yarn clearer even if it cost as much as £5. The factory management, used to spending only a shilling or two on their yarn clearers held up their hands in horror at the thought of such an expense. There was some justification from their own narrow cost standpoint, but on an overall company view it was good business.

There were two problems for Wilson to overcome. Firstly, to convince the people who mattered that the development of an effective yarn clearer could be justified on costs and second that an effective clearer could be designed for production at an economic price.

An electronic yarn clearer became feasible when a suitable photocell was found at the Instrumentation, Electronics and Automation Exhibition in Olympia on the Standard Telephones & Cables stand. This germanium photocell was only 3 mm in diameter and some 10 mm long and operated on low voltage. Its cost was about £1.50, which made it possible to design a yarn clearer capable of manufacture within budget and using the signal from the photocell to operate a yarn cutter whenever a small fault was detected in the yarn passing the photocell. Peter Wilson decided to use a cold cathode trigger tube produced by Ericsson Telephones to operate the cutter using a modified electromagnetic relay.

Thomas Holt and Co, a Rochdale cone winding engine maker, agreed to promote the Wilson Yarn Clearer commercially and a production prototype was made and taken to Erricson Telephone Ltd (ETL) who agreed manufacture the device. Their unit price of £13 for an initial run of 2000 was achieved by using printed circuitry that was then in its infancy and initial order was placed for 2000 units.

In September 1958, Thomas Holt showed the Wilson Yarn Clearer at the International Textile Exhibition in Belle Vue, Manchester as the “Yarnspec”, which was believed to be the World’s first commercially viable yarn clearer.

By about 1959 Thomas Holt had sold some 12 000 units but Thorn Bendix, a subsidiary of ETL dealing with textile applications, began production of a transistorized version which included some 12 or more transistors and superseded the much bulkier Yarnspec. A few years later sales of £400 000 p.a. were being achieved by Thorn Bendix and the era of electronic yarn clearing was well and truly born.