The Tanning Process: Barry Parsons

Creating Yu Mei’s high quality leather is a complicated process, and there are many steps involved in bringing out the character, and natural softness, that deer leather is famous for.

The journey begins once the deer skin has been delivered from the tannery’s protein processing facility. We source our skins for Yu Mei from some of the most highly regarded deer farmers in New Zealand, and they need to be delivered to the tannery within twelve hours of being processed. Once they arrive, we pass each skin through a machine which removes excess tissue—a step that helps create the final grain effect we see in our leather.

Salt is then applied to the skins to preserve them, until we are ready to remove the hair ( the salting process is sometimes referred to as curing ). This is all done within twelve hours of the skins reaching the tannery—if it isn’t done in a timely manner, we risk damaging the grain of the skin. Ideally we then hold the salted skins for approximately four weeks, as it relaxes and opens them up. We personally check the skins each week, to ensure they’ve all been salted and stacked correctly.

The next step is to lime the skins, which is the process of removing the hair. Liming is done in a large mechanical drum, and takes approximately twelve hours. The skins are then de-limed in the drum, before being ‘bated’—this means that enzymes are applied, which helps further soften and relax the skin.

After all the skins have been de-limed, chemicals are added to the mechanical drum to preserve the skins. This is referred to as pickling, and is done in preparation of tanning and colouring of the leather. Once the process of pickling has taken place, the skins are then tipped into holding drums to allow them to drain. They contain a lot of natural fats at this point, so they’re very slippery! Next, we stack the skins on wooden pallets, taking care to avoid any folds and creases. Then they are re-fleshed mechanically. This action is required to even the thickness of the skin, as well as extract moisture. Each skin is machine-fleshed separately, then re-stacked to further drain.

At this point, we conduct an inspection of the pickled skins, checking their general condition after the pickling process to ensure good hair removal and grain quality. Pickled skins can be held in this condition for up to six months, prior to tanning and dying.

The next process is to tan the skin ( essentially changing the skin’s chemistry to make it more durable ). In short, this process is achieved either by minerals, oils or vegetables, but the most common tanning process is mineral tanning. The reason for this is that the skin retains its shape, the leather has outstanding softness, and it’s able to achieve a high colour palette and has good light fastness—meaning once the skin is dyed, the colour won’t fade as much. From start to finish, this can take up to 24 hours to complete in tanning drums. Skins can later be re-tanned to specific tannery or client specifications.

After the tanning process, the leather is then dried and stacked for inspection, prior to colouring. Deerskin requires specialist graders to select skins in the correct thickness and quality for each client specification. There is a very small proportion of skins that are the right thickness and quality for bag production.

Once skins are selected into the correct grade, they are then held for dyeing to client specific colour choice. The colouring process is carried out by dyeing and finishing technicians, who formulate dyes for client-specific colours. This requires mixing and testing several dyes to achieve the accurate colour. Colours can change under different light conditions, so this is a very complicated process which takes a lot of skill.

The dyes we use are water based, and added into large dye drums with the leather in order to be tumbled, which allows the colour to penetrate into the skin. This is known as drum dyed aniline. A small amount of pigment can also be included to level the colour—this is known as semi-aniline, and is ideally suited for the fashion industry. Fatliquor ( fats & oils ) are also added during this process, to assist with the softness of the leather.

After the skins have been dyed, we dry them out. They are then tumble milled in large wooden drums to enhance the natural grain. Drumming can take from one to twelve hours, depending on the softness and effect of leather required.

Skins are then further shaved mechanically to achieve an even thickness across the entire hide, making them ready for bag production. The leather is then checked and trimmed by our highly qualified specialist graders, who do one last check for any imperfections.

The leather is then finally ( ! ) ready for measurement, and can be sent to Yu Mei for them to work their magic.