FINISHING LEATHER

What does leather finishing mean?

Leather that comes from the tannery is rigid, still moist and not visually attractive. The last step, before it can be used to manufacture shoes, involves the leather being taken to the finishing shop. This step includes drying the leather, softening it and enhanced coloration of its refining details.

The leather cannot be processed after pure tanning: it is not ready for use until it has been finished. Leather finishing refers to all the steps that make up the process, such as milling, hemming, neutralising, dyeing, greasing, drying and embossing.

What does milling mean?

The first step of the process involves the leather’s water content being reduced. This stage is known as milling. This used to be done by hand but, today, milling machines, which squeeze the water from the leather, are used to make the process more simple.

What does samming mean?

The semi-dried hides are planed down (‘equalised’) to a predetermined layer thickness.

What is neutralisation?

Animal hides are still acidic until they are neutralised. The next step involves the hide being neutralised, i.e. deacidified. During this step, free acids and neutral salts are removed from the leather and into a barrel through means of brewing. This stage is very important in terms of making the hide suitable to wear.

How is leather dyed?

The leather being dyed is the step that follows the neutralisation stage. The hide is placed is huge barrels and repeatedly turned in organic or non-organic colour until the colour has penetrated all the fibres.

Integral colouration (also known as transparent colouration) is not to be mistaken with topping. This process solely results in a one-sided, surface-dyed leather. The colour is applied by means of a spray gun or by brushing the surface of the leather with the colour. Many low-priced leather shoes produced by other manufacturers are only top-dyed. Sioux uses exclusively dyed-through leather. This results in the colour being of a better quality, lasting longer and being abrasion-resistant. Small damage is immediately visible on top-dyed leather, as the undyed leather becomes visible if the material is scratched. Another important aspect is that dyed-through leather (used by Sioux) is much more breathable than top-dyed leather since the pores of the leather open during the dying process, whereas the pores close during the top-dyeing process.

Why is leather greased (oiled)?

Processed leather is relatively firm until this stage. The next finishing step is the so-called greasing process. This process is carried out in a hot air drum. Various mineral oils (or fats) are added and rotated. This makes the leather more supple, stretchy, tear-resistant and flexible, and adds the typical leather smell. This typical leather smell is therefore not the natural smell of animal skin, but a result of the processing.

What does chemical finish mean?

Another finishing step, which is carried out before the drying stage, is producing a glaze for the shaft leather. This involves the upper layer of the leather being refined. This glaze protects the leather from external influences and preserves the shiny surface.

Why is leather pressed?

The finished outer leather is stretched between metal plates or under heat radiators and dried at between 40 and 60 degrees Celsius. After the leather has been stored for one or two days, it is pressed at 90 degrees using heavy hand irons or a press, resulting in a wrinkle-free surface being formed. Following this stage and a lot of manual work, raw hides have now been turned into a premium material that can be used to create high-quality shoes.