Leather 101
1. Common Myths
c. Oil Tanning
a. Full-Grain
b. Top-Grain
c. NuBuck
d. Suede
b. “Bonded” or Re-Constituted Leather
COMMON MYTHS
There are two major myths that we need to dispel first. These involve the terms “Italian Leather” and “Genuine Leather” and what they actually mean.
ITALIAN LEATHER
Italian leather is thought to be the world’s finest leather. While the nation of Italy does produce some of the finest full-grain leather, they also produce other lower-grade leather products such as bi-cast leather and bonded leather. The quality of a leather hide has little to do with which country it was produced in and more to do with the quality of the raw skin, the tanning process, and the finishing process.
The phrase, “Italian Leather” has also been used on products whose company of manufacture is registered in Italy but actually produces materials abroad.
“GENUINE LEATHER”
The phrase “genuine leather” is typically stamped on to small leather goods as a symbol of quality. Unfortunately, buyers typically don’t know that all genuine leather means is that the material contains at least 51% animal hide. The term “genuine leather” is used either when the producer of the good is unaware of the leather’s origin or when the product is made of either bi-cast leather or bonded leather.
Typically speaking, products branded with “genuine leather” are products of uncertain processing and origin.
LEATHER TANNING
Leather starts as a raw animal hide at the slaughtering house where it is put into a shipping container packed with salt. The salt is enough to preserve the hide for an almost indefinite amount of time. These containers of raw hide are then bought by tanneries on the open commodities market.
In order for the hides to be of any functional use, they need to be preserved through the process of tanning.
Tanning is the act of preserving a hide by removing all of the flesh, hair, moisture and oils and soaking the hide in the tanning solution of choice. There are 3 main types of tanning processes and only one that is used for 80% of leather produced:
CHROMIUM SALT TANNING (“CHROME TAN”)
Chrome tan is the most common modern tanning method. It results in a very supple, slightly stretchy leather that is resistant to water damage. It can be dyed and finished in a multitude of colors and finishes and is used for most applications from upholstery to clothing and shoes. However, chrome tan leathers don’t wear or patina as well as other tanning methods, such as veg-tan.
VEGETABLE TANNING (“VEG-TAN”)
Veg-tan is considered the original, “true” tanning. The leather is tanned in vats with the extracts of bark and leaves from a variety of tree species, mainly oak. The reason it is considered “true” tanning is because the word “tanning” actually derived from the process of using the tree “tannins” to treat the hide.
Unfinished and untreated veg-tan leather is a light tan/pink colour that has a look of “raw” leather. It is a lot stiffer than chromium salt tanning and can also be sensitive to water.
Veg-tan leather is most suited to applications where very heavy-duty leather is required such as saddlery and horse tack, belts, luggage, baseball gloves, medieval costuming, and high-end wallets.
OIL TANNING
Oil tanning is a rare practice that was originally derived from using the oil in the brain of the animal to preserve the hide, as per the saying, “Every animal has enough brains to save it’s own hide.” Oil tanning, typically, also involves using smoke to “lock” in the tan and to preserve the hide’s stretch.
This type of leather is common among hunters and home-tanning enthusiasts but rare for commercial supply. When smoked, it is easily distinguished by the strong, acrid smoke smell the leather has. Many types of “oil tanned” leather on the market are actually veg-tan leather that has been impregnated with oil to make it supple and water-resistant.
TYPES OF HIDES
A tanned, un-split bovine hide is extremely thick, approx. 9mm (3/8 inches). The hide is then separated into several layers, the thickness of each layer being determined by what end product is being made.
FULL-GRAIN
This is the finest of leather: the original grain of the animal’s skin is clearly visible and is free of defects. On a hide, there is only one layer of top-grain so it is extremely valuable. These hides are usually used for only high-end upholstery applications, leather shoes, and high-end leather goods.
TOP-GRAIN
Top-grain is similar to full-grain, however, because of the different ways the animals may be raised, the hide may have a certain number of defects, which are often corrected. These defects may include scars and cuts from barbed-wire fence, branding, and holes from parasites that may have burrowed through the animal’s skin (although parasitic holes cannot be ‘corrected’).
Defects are corrected by lightly sanding off the original grain from the hide and using an embossing stamp to imprint a new grain pattern.
Top-grain is typically used to make “distressed” or other types of leathers with extra finishing processes applied.
However, the stamp used to imprint a new grain may either be a bovine print or it may be one of a variety of other animals such as an alligator or snake. The majority of exotic animal leather available on the market is actually corrected-grain bovine leather.
NUBUCK
Nubuck is top-grain leather that has too many defects in the grain and therefore the entire top layer has been sanded, raising a small amount of nap, to leave a velvety smooth, suede like texture.
SUEDE
The suede is all of the remaining layers that result from the splitting of the hide after the full-grain layer has been removed. Because suede is more abundant than the full-grain (due to the ability to separate multiple layers) it is cheaper and more readily available.
PRODUCTS TO AVOID
The above leathers are all good, natural types of leather products. The deception to consumers occurs when the following products are made from suede and leather by-products to try and fool the consumer into believing that they are full-grain products all the while being labeled as “Genuine Leather”.
“BI-CAST” LEATHER
Bi-cast leather is typically one of the suede splits that then has a poly-urethane “skin” applied to the surface. This type of product is in wide use across the markets: in upholstery, in shoes, and in small leather goods. It typically has a shiny surface and the poly-urethane (in the industry it is known as, PU)skin can usually be scratched off.
No matter what the manufacturer or retailer says, bi-cast leather will never develop a patina or “age well”.
Bi-cast leather can usually be spotted by looking at its surface: it will typically have a very flat colour and a very consistent grain pattern.
“BONDED” OR RECONSTITUTED LEATHER
Bonded leather is kind of like the “ply-wood” or “particle board” version of leather: leather scrap pieces are mulched, glued, and pressed into a solid sheet. This new sheet then has either a print of an animal hide stamped on it or has a poly-urethane “skin” applied to it. If it has a PU skin applied to it, then it is technically also a bi-cast leather.
Bonded leather will tend to be stiff like a natural veg-tan leather but the underside of the material will typically look like it was made of fine mulch. The underside may also have a skin applied to it to help maintain the integrity of the bond.
Unlike natural leathers, both bonded and bi-cast leathers have a limited lifespan before they start to disintegrate. Depending on use, the time for disintegration is typically about 1-2 years.