A made-to-measure shoe is created (6) Grooving
This article is all about the connection of the bottom of the shoe to the upper. When we talk about the bottom of the shoe, we mean the part of the shoe below the upper – it consists of several sub-elements: Insole, (midsole), outsole and heel. In the classic business shoe, these are made from vegetable-tanned bottom leather – a strong, hard and sturdy cowhide made using the pit tanning process with oak tan. The bottom of the shoe is completed by the so-called joint piece. It is used to stiffen the sole of the shoe in the area between the end of the heel and the point of contact with the ground in the ball of the foot – that is, the area of the sole of the shoe that has no contact with the ground in the finished shoe. Often, inexpensive heeled footwear does not have a stable joint piece. This can be seen when the sole presses down unsightly in front of the heel, in the area where it has no contact with the ground. In a high-quality shoe, a harmonious transition from heel to outsole can be seen even under load.
But let’s return to the ground fortification. The bottom, or in simple terms the sole, must be permanently connected to the upper – for this there are various types of manufacture. Traditionally (for hundreds of years), the bottom is connected to the shaft by stitching. It was only in the second half of the last century, and with the further spread of industrial shoe manufacturing, that the use of adhesives in shoe bottom fastening became more popular. However, fastening by means of seams is still the most durable of all shoe bottom fastening methods.
In the case of an exclusive made-to-measure shoe, it is usually the subsequent intended use that determines the choice of fastening method for the shoe bottom. If we assume a classic business shoe at this point, it should be pricked, i.e. sewn, and at best this operation should be done by hand. The fact that this operation is also possible by machine is proven by the Goodyear-sewn specimens – the mostly less expensive representatives in the made-to-measure shoe segment or prêt-à-porter sector – more here.
As already mentioned, the supreme discipline is the hand-pierced shoe. Here, a specially braided yarn, called wire, is used to attach the frame (a long, specially prepared leather strip) to the shoe by means of the single-stitch seam. In the process, the frame, upper and insole are sewn together. This can be done with the help of various techniques, which differ in detail – the goat-sewn and welted shoe are mentioned here as representatives. Depending on the type of bottom fastening, for example in welted shoes, this seam does not run all the way around the entire shoe, but only from heel to toe to heel. In contrast, in goat-sewn models, the single-stitch seam runs around the entire shoe.
In order for the frame to fit evenly to the shank and to facilitate the piercing of the leather, the frame is completely soaked so that it becomes soft, pliable and supple. The same applies to the insole. An awl is now used to pierce through the dam of the insole, shank and frame. Then the wire is passed through each hole crosswise and tightened – stitch by stitch. The distance between the stitches varies between approximately six and ten millimeters. One can therefore guess that this operation is in any case a very time-consuming and labor-intensive manufacturing step that demands a great deal from the experienced shoemaker in terms of technology and, above all, in terms of effort.
After the frame is attached, excess material is carefully cut from the frame and shaft without damaging the seam. The joint piece is then inserted. There are various materials used here for this stiffening element. The spectrum ranges from wood or metal to fiber-reinforced plastic and is used manufacturer-specifically, depending on the philosophy and price range accordingly.
Before the outsole is applied, the bottom of the shoe must be smoothed and any unevenness levelled out to prevent cavities in the sole area later on. This is done with the help of the so-called balling out. For example, a cork layer is glued on or a so-called balancing compound is applied. This is then sanded with a rasp or on a grinder until the bottom of the shoe is evenly smooth.
In the following production step, a second seam is set – the double seam. You can find out more