Coloring leather is not always a piece of cake. So, it is pulled through gently with great care and absolute correctness. Generally, it is known more commonly as “Leather Dyeing.” Dyeing leather can be considered as one of the crucial stages in leather making or manufacturing. As said, an excellent dyed leather stays healthy for ages, less prone to crack or wither, and is able to maintain its shine and glory for a long time.
However, the initial color of the leather before dyeing solely depends on the tanning agents used. Leather has been around us for quite a long time. Medieval leather dyeing techniques mostly used natural substances that were collected locally and some acids to bind them to the leather’s collagen proteins, though they weren’t as long-lasting as modern day’s advanced dyeing techniques.
Modern-day leather dyeing techniques are optimized after sufficient experiments and research, as compared to their predecessors. There are two types of dyes that are most prominently used in the leather industry for dyeing;
- Solvent-based leather dyes.
- Water-based leather dyes.
Leather is dyed by both, master craftsmen in small scales and by advanced bulky machines in industries (Tanneries).
Dip Leather Dyeing:
Dip dyeing can be considered as one of the traditional methods. And as the name conveys, it consists of dipping the raw tanned leather into a bath of dye(s). The leather is left to stay submerged in the bath of dye for sufficient retention time so that the dye binds itself to the leather on the molecular level. This technique is employed by both small and large scales, though with different approaches.
On a small scale, master artisans make use of a big drum, which is usually filled with dye, then leather is then gently lowered into the dye bath, the temperature profile is maintained to ensure smooth operation. After pulling out the leather from the drum, it is then dried out to strengthen the dye. The dry time generally depends on how long the leather was kept submerged under the dye. This process, however, is difficult and requires adequate manpower to do the job, and the dye consumption is pretty high.
Leather is Dip-Dyed commercially on a large scale in industries (Tanneries). First things first, leather straight off from the tanning process is sent into a huge rotary drum along with solution and dyes. The drum is then tumbled at a specified rpm (Rotation per minute) heated between 50 degrees to 60 degrees Celsius in order to favor the dyeing operation furthermore. The retention time is monitored, and thereafter the leather is dried to ensure the dyes and solutions bind firmly to the leather.
Brush and Sponge Leather Dyeing:
Conventional dyeing methods can sometimes damage delicate and expensive leather, they require gentle dyeing strategies, and that’s where this process kicks in. The process typically is done by Brushes and Sponges, depending primarily on the sensitiveness of the leather.
Normally, brushes are used to apply the dye effectively on the leather smoothly and evenly. The leather is spread out on a slightly convex surface to expose more surface area to cover.
For fine and delicate leathers, sponges are used to coat the dyes and solutions for a uniform and even finish, as the brush fibers are prone to scratch off the sensitive leather.
This technique of leather dyeing is efficient in terms of minimal solvent and dye wastage, and a relatively lower amount of paint and binders are required as compared to the conventional dyeing methods.
Spray Leather Dyeing
Spray dyeing technique uses a whole assembly of machines to produce a finished product, and as the name indicates, this method uses small nozzles to squirt the solvent directly onto the surface of the leather evenly and smoothly. Of all the leather dyeing techniques, spray dyeing stands out prominently because of its speed of dyeing operation, a minimal amount of dye usage, and efficiency.
This method uses spray guns with rotating small nozzles to apply the color and solvents to every edge of the raw tanned leather rapidly, continuously coating the leather from every possible angle. This efficiency of operation makes it time-saving and saves a lot of paint and solvents. This method minimizes the need for labor by using computer precision soft wares. But the more the machinery is used, the more frequent maintenance is required.
Out of the many stages in leather manufacturing, leather dyeing is said to have the utmost importance in prolonging the leather’s lifespan and gives it more appeal aesthetically.