How Tanned and Untanned Cow Hide Are Processed
What is the difference between tanned and untanned cowhide? To begin, untanned cowhides are soaked in acid to prevent decomposition. The hides are then dyed and cured with fat or oil, before undergoing tanning. The process can take up to five years, depending on the hide type. This article will explain how untanned cowhides are processed.
Untanned cowhides are soaked in acid to prevent decomposition
The process begins with the preparation of the hides. They are first soaked in acids, such as milk or lime. The acid is classified as a weak acid. Afterward, the hides are stretched, fatted, and dried. If not replaced periodically, untanned cow hides will decompose and become rawhide. Native Americans traditionally wore clothing made of rawhide. Historically, leftover leather was used for glue. Tanneries would place scraps of hides in a vat of water, pour it over a fire, and boil the water off to create glue.
After this process, the untanned cowhides are cut in half. One half is salted with 50% sodium chloride and the other half is preserved by oxidation. The hides are then wrapped in polyethylene film and stored at 22oC to prevent desiccation. In the past, hides soaked in acid had a short shelf life, and today, untanned cowhides are still used for furniture, but they are not as popular as they once were.
They are dyed in enormous drums
Tanning takes place in several steps. First, a tanned cowhide is washed with water to remove soluble salts and then placed in a drum that rotates in the air. The stock is then filled with coloring matter. The hide is dyed in drums that are usually heated to sixty degrees Celsius. The process typically takes between one and three hours.
Aniline dyes penetrate the leather surface and are applied by hand or in enormous drums. They produce a uniform appearance but are not suitable for bright, white or black colors. Aniline dyes stain easily and are not suitable for a range of bright colors and patterns. However, they are perfect for achieving a patina. However, dyeing is an extremely time-consuming process, which is why untanned cow hides should only be dyed once in their lifetime.
They are tanned with tannins
Tanning a hide is a process in which the skin of an animal is coated with an organic substance called tannic acid. The purpose of tanning is to stabilize collagen, the main structural protein in animal skin. Tannic acid is an antioxidant that protects the skin from rotting and decay. Tannins are naturally present in some barks, galls, and plant tissues. They are also used in leather production to protect collagen from degradation.
Cowhide is naturally speedy, whereas un-tanned cowhide has little texture. The bovine Pelle is particularly hard, strong, and flexible. The hide produced by cows in hot climates tends to have more scarring due to insects, while in cold climates, fewer pests can damage the hide. During the tanning process, the hide must be tended to frequently, to ensure full absorption of tannins. The hide is then removed from the tanning liquid and shaved to the desired thickness. The un-tanned cowhide will have a pale brown hue. The dyed version of the leather will be much richer in color, with character and depth.
They are cured with fat or oil
Curing untanned cowhides can be done by drying, stretching, and fatting them. Rawhide is formed when untanned hides are not replenished periodically. In the past, leftover leather was turned into glue. Tanners would soak scraps in water and boil the mixture over the fire to produce glue. The process of fat tanning is different from vegetable tanning.
This process is one of the oldest forms of tanning. Curing is an important part of leather making, as it prevents the putrefaction of collagen and increases the moisture level of the hide. In addition to decreasing moisture content, curing also creates a high osmotic pressure, which prevents bacteria from growing and killing the hide. In many cases, untanned cowhides are cured with fat or oil, which is an environmentally friendly way to preserve untanned cowhides.