The chromium neutralizes all tonal variation in the skin to this light blue, reducing the appearance of natural marks to near zero.Ĭhrome hides being split to achieve even thickness When the tanning process is complete, chrome tanned hides are a light blue (referred to as wet blue), a result of the chromium held within the hide. Rather than weeks, this process can be completed in a day, resulting in a much more affordable leather. Invented in 1858, chrome tanning is the process of tanning hides in chromium sulfate and other chromium salts, rather than natural tannins. We’ll follow up with another post on these soon* *The long history of natural leather tanning means there are a lot of wild stories and techniques, all that have had an impact on the culture of the modern leather industry. This process allows veg-tan leathers to naturally biodegrade if disposed of. The leather can also be “stuffed” with natural oils, resins, and/or waxes to make it more supple and give it unique characteristics. Veg-tanned leather has a natural stiffness that allows pieces to stand up to heavy wear and tear. These colors take time to penetrate the skin, and in some cases only color the exterior sides, leaving the flesh in-between a light, natural color.
To make tan, brown, black, and other colors, the natural leather is drum dyed to achieve the desired color. This color is the most susceptible to color change as there are no dyes to mask the oils and UV rays it comes into contact with. Once complete, the leather is in its natural color. Over the weeks the hides are progressively moved into vats of higher tannin concentration, resulting in a very strong, evenly tanned leather. The hides are then stretched on racks and submerged for several weeks. Natural hides stretched on racks and submerged in tannin baths Recipes of these materials are closely guarded secrets of each tannery, giving each its own unique style of leather. Trees like chestnut, oak, and hemlock have long been used in this process. In leather manufacturing, these tannins are sourced from tree barks and leaves - which are ground to speed up the extraction process. Tannins are naturally occurring molecules found in most plants (it’s what makes red wine dry and unripened fruit tart). Made by impregnating the hide with natural tannins, it can take up to sixty days to complete this initial step on a single skin. Tanned, natural hides in storage before going into the finishing processĪlso known as veg-tanning, this natural process predates Ancient Rome and Egypt. This is the step that converts a hide to leather. Tanning is the process of permanently altering the hide's protein structure to make it less vulnerable to decomposition. There are two main techniques of tanning that define nearly all leather used today.
The prepped hide then moves to the tanning stage where the quality, appearance, and characteristics are determined. The process removes moisture from the hide, cleans off any hair and tissue, and establishes its pH. Today, almost every variation of leather found in the market stems from these three techniques.Īll leathers begin in the same process of basic preservation and cleaning. Today, only a handful of tanning methods are still used in the production of cow-hide leather, each with their own pros and cons. Ever wonder what makes leather different from a decomposing body? It’s a technique used for thousands of years, invented and reinvented by cultures throughout human history.