A welt is a strip of leather, rubber, or plastic that runs along the perimeter of the outsole and is stitched to the upper and a strip of canvas (known as "gemming") which is cemented to the insole of a shoe, as an attach-point for the sole. The space enclosed by the welt is then filled with cork or some other filler material (usually either porous or perforated, for breathability), and the outsole is both cemented and stitched to the welt. This process of making shoes is referred to as Goodyear welt construction, as the machinery used for the process was invented in 1869 by Charles Goodyear, Jr., the son of Charles Goodyear. Shoes with other types of construction may also have welts.
The Goodyear welt process is a machine based alternative to the traditional handwelted method (c. 1500 AD) for the manufacture of men's shoes, taking its name from the inventor who devised the original machine to replace the earlier completely hand sewn method. The benefit of a shoe which is made using the Goodyear welt construction is that the shoe can be resoled repeatedly, giving the shoe a lifespan of years, sometimes even decades. Some claims towards added ventilation have been made as well but there are no proven studies comparing the breathability of different shoe construction methods.
The upper part of the shoe is shaped over the last and fastened on by sewing a leather, linen or synthetic strip (also known as the "welt") to the inner and upper sole. As well as using a welt, a thread is used to hold the material firmly together.
The welt forms a cavity which is then filled with a cork material. The final part of the shoe is the sole, which is attached to the welt of the shoe by some combination of stitching along the edge of the welt and sole, and a high strength adhesive like contact cement or hide glue. The Goodyear welt is highly regarded for a number of reasons including being relatively waterproof by not allowing water to get into the insole due to the welt-sole construction, the relative ease in which the sole can be replaced, and the fact that the shoe can last up to 20 years or longer depending on the treatment and condition of the upper.
The nature of this shoe construction means that Goodyear welted shoes take longer to manufacture than cheaper alternatives, and requires the use of skilled labour.
- Thomson, Ross (1989). The Path to Mechanized Shoe Production in the United States. University of North Carolina Press. ISBN 978-0807818671.
- Video: How Goodyear Welted Shoes are made USA ca. 1930
- pdf Document: The manufacture of boots and shoes : being a modern treatise of all the processes of making and manufacturing footgear (1902)
- pdf Document: Original Goodyear Welt Patent 1869
- 3D Animation Goodyear Welted Patent
 R.A. Salaman, The Dictionary of Leather-Working Tools c. 1700-1950, Allen & Unwin, London 1986. pp.182
 J.H. Thornton, Northampton College of Technology, Textbook of Footwear Manufacture, pps. 28-32, National Trade Press, UK 1953
 F.Y. Golding, edited by, Boots and Shoes, Vol. VI, pp.178 The New Era Publishing, London 1936
- R.A. Salaman, The Dictionary of Leather-Working Tools c. 1700-1950, Allen & Unwin, London 1986. pp.182
- J.H. Thornton, Northampton College of Technology, Textbook of Footwear Manufacture, pps. 28-32, National Trade Press, UK 1953
- F.Y. Golding, edited by, Boots and Shoes, Vol. VI, pp.178 The New Era Publishing, London 1936