In shoe manufacturing we have a saying: “Last comes first.” Virtually all shoe development and production starts with a last.
A last is a foot-like form used to shape shoes during the crafting, manufacturing or repair of footwear. Both the fit and the overall look of a shoe are entirely dependent on the design, shape and volume of the last that it was built on. Each last is designed to accomplish particular heel and toe shapes, width and girth measurements, as well as other aspects of fit and contouring that are desired in the end product.
This form can represent the anatomical information of the foot to varying degrees of accuracy. Most footwear is made on lasts that are likely to accommodate the majority of ‘average’ feet. However, it is also possible to design custom lasts based on the exact measurements of a person’s foot for use in custom medical or bespoke shoemaking.
Historically, lasts were made from hardwoods or iron due to their durability when subjected to the rigors of shoemaking. The form must hold its shape against tacks, moisture, temperature fluctuations and the pressures of stretching leather and other materials, whether by hand or machinery.
Design and Production Files
As lasts were once made of a wider array of materials, they could be shaped by carving, casting or milling. In the latter part of the 1900’s, last shapes came to be designed primarily using dedicated software. Because of this, milling and molding have become the primary modes of producing lasts, as the data can be directly translated from these programs to the mill or blueprints for a mold. These mass production processes for last making result in a much more accurate and efficient process for designing and cutting lasts.
Designing and modifying lasts via software also has the benefit outputting digital last production files. Lasts that are developed and made by hand need to then be digitized and graded for production. This process opens the last up to iteration related error, much like a game of telephone. Starting development with digital last files allows last makers to spec lasts more accurately and also makes for a more seamless transition of files from sample making to production.
Plastic vs. Aluminum vs. Wood
These days, especially given the mechanical stresses put on lasts in mass production, the industry has seen a move toward plastic lasts. Not only can the warping associated with wood be avoided, but high density plastics can be 100% recyclable. Instead of discarding old last inventory into landfills, they can be melted down to form new lasts when they’ve become too worn to use.
In the case that a shoe construction requires extremely high heat, as with vulcanized sneakers, lasts will be milled out of aluminum so they won’t melt during production. While these are just as accurate as milled plastic lasts and can also be recycled, they are much more expensive to produce due to the cost of both the raw materials and mold development. Because of this added cost, working with aluminum lasts typically only makes sense for high volume footwear orders that allow for this expense to be amortized.
While wood is a beautiful material to work with, it is much harder to control for accuracy and consistency. Because different woods have varied levels of density and react differently to moisture, they can warp and shrink significantly enough to affect the accuracy of a shoe’s fit. For a one-off shoe, however, this does not pose a problem, so wood still sees frequent use as a last material in custom and bespoke shoemaking.
When working with your footwear developer and manufacturer, it is important to understand what the last development process is and what type of lasts will be used for production. Making informed decisions at the beginning of the process can save significant time and money.