How is Leather Made?
HOW IS LEATHER MADE?
How is leather made? Many people, even designers who work with leather regularly, don’t know. At Stonestreet, we are passionate about leather manufacturing and are happy to help educate others.
How Is Leather Made? A Step by Step Explanation
Just how is leather made? From aspiring fashion designers to hunters, many people wonder about this. The modern leather-making process is a collection of as many as six phases, which we will outline below.
1. Prepare raw materials.
Leather making starts with raw animal hides, which are typically obtained from a supplier in commercial leather making enterprises. These hides are often packed in rock salt for preservation and kept like this for up to 30 days. This piece of the “how is leather made?” process has remained almost the same since the earliest humans began making leather.
Later, salt is removed by from the hides by tumbling and hammering the hides. Hides may also be placed in soaking drums for a couple of days to rehydrate the material and remove any remaining salt and grime. Hides are treated to remove any hair or remaining animal flesh, and also to soften and increase the hide.
At the end of the preparation step, the hides are sliced into two layers by a splitting machine. The bottom portion (termed the reticular segment or split) is utilized for cheap, inferior leathers. The top portion (termed the papillary segment or dermis) is employed for high-quality, full-grain leathers.
The principal tanning step converts hides into leather by halting and preserving this hide’s decomposition. Hides are put into a drum along with either chromium salts or vegetable tanning agents and rotated for around eight hours. The salts and tanning agents preserve the leather as well as soften it.
After tanning and fat liquoring, hides are placed in a machine for sammying. Sammying is the removal of moisture through pressure. Following this, the hides may be sorted by quality and shaved down to uniform thicknesses.
The next step in how leather is made is retanning. This is step is done in order to alter the features of the leather to suit its use. Leather is tanned with a combination of vegetable matter and chromium salts, providing texture. Hides are set in a machine for a second time to remove moisture.
Then, the hides are sorted and stored once again. Hides may be air-dried, vacuum dried, or oven dried. After drying, hides are made supple and soft via mechanical softening done by a machine.
Dyeing leather is a long process. Hides are put into dye drums and following eight hours, they are tested to assure that the hides have been saturated by 100 percent of the dye. Hides are air or vacuum dried again at this point.
Finishing is an optional step in the “how is leather made?” process. It ensures softness and malleability and provides the required level of gloss, when applicable. The role of finishing is to minimize the look of grain or blemishes in the hide and to supply a pattern if desired.
One part of this is the grinding process, where hides are in climate-controlled drums, to soften the leather. Hides are stretched onto frames for four to eight hours to tighten the fiber structure. Some leathers receive a minimal application of pigment or surface finish.
Finally, a variety of tests are done on the leather to guarantee high-quality. These tests include dimensional stability, abrasion, fading, and color. Hides that meet the quality specifications are stamped and are labeled with the area in square feet or square yards. The hides are rolled into tubes or draped on a horse to protect against any wrinkles or folds when sending.
Now you know the answer to the question, “How is leather made?” because Stonestreet Leather taught you in this step by step guide.
How to Make Leather: Automation vs. By Hand
How to make leather has changed throughout the years. The livestock and agriculture industries have expanded alongside technology; together this has made way for the growth of modern leather tanning processes. Most modern tanneries are safe and clean with large quantities of light. Automation has enabled quality control in leather making and has made the process, as outlined in the previous section, much faster than it used to be.
It is still possible to make leather by hand, though, and the fundamentals of the process match the automated processes many leather manufacturers use today. If you are a hunter, artist, or DIY-er, here are the basics of how to make leather by hand. Be warned, the process takes an extremely long time!
First, set up a work area either outdoors or in a ventilated, easily-cleaned indoor space. You’ll require a work surface at least as big as the skin you’re working on. Soak the hide in water overnight to make it pliable. Lay it out flat, then carefully scrape the flesh off the skin with a sharp convex drawknife or blade.
Next, the hide must be de-haired. Mix up a solution of 2 cups lime into 1 gallon of water (make enough to completely cover the skin). Soak the hide in it and then scrub/scrape off any remaining hair.
Although the hide now looks clean, there is still more scraping to do because there is a tough membrane that remains. Let it dry, then scrape with sharp blades. You can use sandpaper on any tough spots.
Finally, the skin is prepared to be tanned. Collect oak or hemlock bark from fallen trees (this may damage or destroy living trees). Add the bark to a huge container of water such as an empty trash can, and soak the hide in this bark “tea” for up to nine months. In this time, the tannic acid (where “tanning” gets its name) in the bark will seep through every pore in the skin. You may want to add new bark and change the water every so often, maybe once every three months.
Once it’s done tanning, take it out and clean it well, scraping at it with a blade and scrubbing. The final portion of the procedure, currying, is turning the preserved but coarse skin into a final product. Poke a series of holes along the border of the hide using a leather awl. Thread ropes through the holes and stretch the skin taut on a frame where you will leave it to semi-dry.
Scrape both sides with a blade or rub a rod or kayak paddle over the surface. This procedure called sleaking rapidly stretches the leather which makes it smooth permanently soft, and supple. You may want a second person to help with this step, as the skin MUST be aggressively and constantly sleaked until tender. The longer the leather is sleaked now, the better the final product will be.
To finish off making leather by hand, you can smoke the leather over a flame for additional waterproofing. Or you can move on to the final step, which is a bit more sleaking while you rub the hide with oil.
Congratulations, you’ve made artisanal leather! This can be used for some really beautiful handmade leather goods.
How Leather Is Made: Top Grain, Split, and Bonded Leather
There are three major categories of leather, top grain, split, and bonded. The process of how leather is made varies slightly for each category.
Top-grain leather contains the outer layer of the hide, known as the grain, which features finer, more densely packed fibers, resulting in strength and endurance. Depending on thickness, it might contain some of the fibrous underlayer, known as the corium.
Types of top-grain leather include:
- Full-grain leather, which includes the grain layer. It is considered the highest grade leather. Footwear and furniture are usually created from full-grain leather.
- Corrected grain leather, where the surface is subjected to treatments that create a more uniform look. This involves sanding away flaws from the grain or buffing, then dyeing and embossing the surface.
- Nubuck, a top-grain leather that has been sanded or buffed to give a nap of protein fibers, making a velvet-like surface.
Split leather is created from the corium after the top-grain has been separated from the hide, known as the drop split. In hides that were thicker, the drop split can be split a second time.
Types of leather made from split leather include:
- Suede, which is produced to create a soft, napped finish. It’s often made from younger animal skins, as the skins of adults often result in a rough nap.
- Bicast leather is split leather that has a vinyl or polyurethane layer placed on the surface and embossed to give it the look of a grain. It’s a bit stiffer than leather but includes a texture that is consistent.
- Patent leather is leather that has been extended a high-gloss finish by the addition of a coating. After inventor Seth Boyden developed the first procedure for large-scale production of patent leather, employing a lacquer, in 1818. This is when it became very popular, however, patent leather has been around since the 1700s.
Bonded leather, also called reconstituted leather, is a material that uses leather scraps that are shredded and bonded together with latex or polyurethane onto a fiber net. The quantity of leather fibers in the mix varies from 10% to 90%, so this type of leather varies a lot from piece to piece.
What Is Leather Made From?
It’s understandable to wonder what is leather made from since it can be made from the hide of just about any animal. On the other hand, the hide most commonly used is that of a cow. Studies have revealed that 65 percent of leather comes from cattle while 15% comes from sheep, 11% from pigs and 9% from goats. Less than 0.2% of leather comes from another sort of creature.
Exotic leathers, such as snake, alligator and crocodile skins, are considered by most as unethical because in these situations you are not using the rest of the animal, as you do with cattle, and in certain cases, the animals are endangered. However, this varies throughout the world. For instance, ostrich is a popular substance used by some designer labels due to its texture and is imported from Africa, where the meat and eggs are also utilized.
Most leather we use today is a by-product of the dairy and meat industries. Instead of wasting the skin, by making leather, the creature’s hide is turned into a beautiful and useful material that will last for decades.
Tests performed on ancient leather samples have revealed that a wide variety of creatures were used for leather in the past, such as alpacas and squirrels, rabbits, beavers, goat, deer, and camels. In these instances, people would want to utilize every bit of the creature for tools food and shelter, which can be when they began using animals.
At Stonestreet Leather, our story is inspired by the rich history of leather-making in the Americas.
Making Leather: Environmental Impact
In the news, we often hear about the environmental impact of making leather. This is fair since there are some things to be worried about in the leather-making process. For instance, people may criticize industrial farming practices used in raising the cows, or they may criticize the substances and processes used at some tanneries.
However, leather products stand the test of time. Leather goods generally last twice as long (or even more) when compared to a synthetic alternative, so that halves the environmental impact.
When it comes to tannery practices, Timberland and other leather retailers have partnered to form the Leather Working Group. This coalition works to raise awareness and has crafted a rating system for tanneries according to their environmental impact.
Making Leather: Environmental Impact of Vegan Leather
Though it doesn’t use animal products, pleather or vegan leather does have some negative environmental impacts too. Think hard and long before choosing these products if you are eco-conscious.
Most fake leathers are made of some kind of plastic product or even petroleum. Some artificial leathers are even made of polyvinyl chloride (better called PVC), something that includes, one of the not-so-nice compounds, phthalates. Plus, these faux leather goods often do not last as long as real leather, so they add to the waste in landfills around the world.
The Leather Process
How leather is made varies somewhat around the world, and different areas specialize in different pieces of the leather process. At the moment, the six countries producing the most leather are China, Brazil, India, Italy, Korea and Russia.
Hides are often acquired from animals in these countries and are then shipped to be processed. A high-end designer in France might buy leather from China, ship it to Italy where they are famed for their tanning methods, then re-import the finished leather back to France to be made into handbags or shoes.
There are many steps to the leather process and many ways of making leather. Curing is an integral step regardless of what else you do, and finishing the leather is an interesting piece since it is an area where you can play with the material for unique results.
How to Cure Leather
You cure leather at the very start part of the tanning process. This is key because raw hides and skins have to be stopped from deteriorating or rotting before the leather-making process begins. Methods of preservation include salting, chilling, freezing and using biocides.
Curing prevents bacterial growth on the hide. It also considerably reduces the moisture content of the hide. One popular how to cure leather approach is wet-salting, in which the hide is heavily salted and then stored tightly packed for up to 30 days. Leather may also be cured by soaking in salt water.
How to Finish Leather
Although not all leathers are finished, it is interesting to look at how to finish leather since you can create some beautiful and unique effects in this part of the process.
For instance, mother of pearl could be inserted to give it a unique, pearlescent finish. Or, embossing, textural changes, or a grain pattern might be performed.
Most full-grain leathers bypass the finishing stage and move straight to ironing. Ironing is another process that uses heat and pressure to achieve varying levels of sheen on the leather.
If you have questions about how leather is made or are looking for a specific style or finish on your leather, contact Stonestreet Leather today.