Lets Talk Materials

Like, really get into it, this page isn't going to be for the faint of heart.

Exploring Some Material Science

Much of the inspiration for Morning Cup Leather comes from a commitment to highlighting the high-quality materials we use and the incredible properties they possess. Check out the tabs below for a deep dive into why we use what we do and how much of the hand-crafting process is more important than you might expect.

What is Leather?

That may sound like a silly place to start but we think that most people's understanding of it is as a luxury material, only useful in incredibly high-end bags and fancy car upholstery.

It's important to remember that humans have been tanning and using it for many thousands of years, with the first leatherworking tools being dated back to 5,000 BC (although evidence of tanned leather can be traced back over 400,000 years). At this point, it was used to build shelters and shoes, although during the bronze age, this was expanded into shields and armor, illustrating the versatility of the material. The Romans expanded this into belts, saddles, and other straps while in Egypt, they were already using to craft jewelry and bags.

In all of these cases, we see leather highlighted, not just as a textile for the wealthy, but as a substance with a myriad of properties allowing it to act like silk or steel depending on the need.

Early examples of Roman footwear made up of tanned leather straps

Okay sure, but what IS it?

One step of the drying process, courtesy of the Wickett & Craig Tannery

Leather is the tanned hide of basically any animal. You can make leather from the hides of alligators, ostriches, and even stingrays. For our purposes, however, we'll be taking a look at the most common type - cow leather. When an animal is skinned, the fibers of the hide are raw (hence "rawhide" if you've heard the term before). The process of tanning converts these fibers into a permanently stable form, ensuring that they are no longer able to rot.

The term tanning comes from the tannins used in the process (although actually, it's technically the other way around, the etymological origin of tanning is a Celtic word for tree, go figure), compounds found naturally in almost all vegetable matter. Tannins are what cause tea leaves to darken water when you steep them. They're also responsible for the 'tannic' or drying taste of things like over-steeped tea or a glass of dry wine (this experience is the feeling of the tannins binding with the proteins on your tongue and VERY slightly tanning it, just as they would leather, freaky!). The tannic compounds from tree bark and other vegetal sources are extracted and applied to the raw hides in large vats where these compounds bind to the proteins in the rawhide fibers, forming a semipermeable layer that prevents decay and causes the hide to officially become leather. More specifically, the fibers become resistant to the hydrolysis of bacteria that cause putrefaction This process takes about six weeks to complete. There are several other types of tanning but all the leather we use is vegetable tanned. It takes the longest but it's also the best for the environment.

Unique Properties

Leather (specifically vegetable tanned for this conversation) has a handful of physical properties that make it an incredibly unique material. First of all, at a normal temperature and humidity, it's an almost entirely elastic material. Even if it may not seem like it, leather stretched along a single axis (before failure) will eventually return to its original shape. Since it is a fiber-based material, it does this along all axes. The caveat to this is that if heat and/or moisture is applied, any deformation can become plastic, meaning if you soak leather and apply heat before and during any kind of deformation, this will permanently shape and mold the leather. This is why you can so successfully make things like gun holsters, knife sheathes, and briefcases.

Additionally, vegetable-tanned leather generally has waxes and oils that are impregnated into it during the tanning process, making it highly water resistant despite being entirely naturally derived. It also, unlike chrome-tanning (a chemical tanning process using chromium salts), will continue to darken with handling and sun exposure, leading to unique patinas that increase its water resistance, strength, and aesthetic appeal over time.

Chart illustrating the comparative Moduli of Plasticity for different materials. Note that leather's is significantly higher than vinyl and polyurethane, despite being the only natural material tested. (G. Lewis, 2003)

Example of patina on a wallet, the one on the left is brand new, and the one on the right has experienced constant polishing from rubbing against the fabric of a pocket and exposure to hand oils

Common Threads for Leather

People have been sewing things together for many tens of thousands of years. The first eyed sewing needles were unearthed in what is now Siberia, and have been dated back 45,000 years. While nearly all stitching in pre-historic leather samples would have rotted away long ago, it can be assumed that sewing has been a part of leather craft for nearly as long as humans have been tanning hides.

For most textile applications, cotton thread is extremely common but when it comes to leather, you'll very rarely see any. This is because cotton thread can rot, which is usually a concern for leather goods that see a lot of wear and use. As an alternative, the primary natural fiber that's used is waxed linen. It's naturally a bit stronger and more resistant to rot as it is derived from flax rather than cotton. The wax also helps to waterproof it a bit. That said, it still isn't impervious to the elements so most modern leather workers have instead turned to polyester.

Despite its heartiness, linen thread can still degrade over time, especially with exposure to water. Since small leather goods like wallets and watch straps are constantly at risk of this, either because of a surprise rainstorm or an accidental tumble in a lake, polyester offers an attractive alternative. In most cases, this thread is still waxed, which both prevents water from soaking into the thread and being held against the leather along the stitch line and makes it glide through stitching holes more easily during the sewing process.

Cotton thread being spun

Example of flax drying in preparation for the production of linen

Types of Stitching

Example of baseball stitching

Example of how saddle stitching differs from lock stitching, courtesy of bestleather.org

If you've ever noticed a stitch line on a manufactured piece of clothing, you've certainly seen a lock stitch, the most common modern stitch in the world. This is what you get from almost any sewing machine. It's an excellent option for sewing quickly as it requires only one needle and can be automated. The major downside is that if one stitch breaks, the entire line can unravel (something you've likely experienced if you've tugged a thread on an old T-shirt). Any leather goods made on a machine use this type of stitch. By no means is it bad, but like anything, it has its benefits and drawbacks.

From here, we can get into the world of hand-stitching. One of the most recognizable leather stitches is the baseball stitch. It has an iconic 'V' pattern that requires two needles on either side of the same length of thread, with one passing underneath the leather at each stitch. this is great for joining two pieces along their edge without any bends or creases in the leather.

If you want to join two pieces of leather with faces against one another (as is most common in wallet construction), the saddle stitch has best withstood the test of time. It's also the one that we rely on here at Morning Cup Leather. It was originally developed and named due to its use in saddlery as makers of equestrian gear needed a stitch that was incredibly hardy and could stand up to extensive wear, but could also be repaired quickly and easily in the field. Because of its structure, if one stitch breaks, it has little to no impact on the stitches on either side and can be fixed by simply burning the ends of the loose thread.

Two needles are used at either end of a single piece of thread and each needle passes through each stitching hole. The friction of the two pieces of the same thread next to each other prevents pulling and keeps the thread very close to the surface of the leather, preventing abrasion and wear. To remove a line of saddle stitching, you would need to sever every single stitch, one at a time.

The Thread We Use

At Morning Cup Leather, we settled on Ritza 25 Tiger thread from Julius Koch out of Germany (specifically in 0.6mm which we think suits our 4 mm stitch spacing nicely). This particular thread is 100% polyester which means it will never fail due to microbial deterioration. It's also been waxed at the factory lending it both water resistance and low friction when sewing. Julius Koch was started in 1895 and although they produce excellent thread for hand stitching leather, their primary products are strings for blinds! Not important, just interesting. They focus on sustainability, using recycled materials in thread production and selecting only low environmental impact dyes.

The incredible logo on the German-made Ritza 25 Tiger thread

Brass as an Alloy

Brass is a fascinating metal that saw the beginning of its popularity around 500 BC (although there has been evidence of similar alloys found from closer to 3000 BC). It is an alloy of copper and zinc, in a roughly 67% to 33% ratio. While similar to bronze, a more well-known alloy of copper and tin, it has its own unique properties that make it stand out as an incredibly useful and beautiful material. To understand it as a mixture of two things, we must first quickly dive into the base metals.

Example of a brass baptismal font from Belgium, made in the early 12th century A.D.

Copper and Zinc

Copper holds an interesting position in the periodic table as one of the most conductive elements in the natural world (second only to silver, which is rarely used in conductive applications due to its poor thermal resistance, a flaw copper lacks). It's also very malleable, making it easy to shape and smith. Finally, it possesses a beautiful orange/red color that lets it stand out against most other metals.

Zinc is a far more brittle and rigid metal with a blue-white luster, making it unpopular as a stand-alone material for many applications that require greater malleability. It does, however, have a relatively low melting temperature, which is untrue for many other hard metals, making it a perfect additive when trying to create a stronger alloy of copper.

When combined, these two metals create brass, gaining a yellowish hue from the mixture. Additionally, brass is stronger than either base metal, with a higher tensile strength than both.

Example of raw copper in its natural state

Examples of zinc at several points in processing

Properties of Brass

Brass does a good job of taking the best qualities of copper and zinc and combining them (metallurgy is awesome!). It's relatively easy to work with and has unique sonic properties that make it great for making instruments (hence why the Brass Bands we love so much here in New Orleans are so named). More useful to us as lovers of leather goods, it's incredibly corrosion-resistant, particularly against salt water. This means that very little you interact with on a daily basis can impact the integrity of brass. Since it is non-ferrous (no iron), it doesn't rust and is not ferromagnetic so you don't need to worry about it interacting with magnets. This also makes it much easier to separate out for recycling.

We'll get further into this in the patina section but brass also creates its own protective oxide layer that prevents almost all oxidation below the surface. This is great because it means brass will not deteriorate under almost any conditions beyond a layer only a few atoms thick on the surface. Additionally, brass exhibits anti-microbial properties as cuprous (of-copper) metal ions on its surface will disrupt proteins and destroy DNA in single-celled organisms through the oligodynamic effect, killing them. For this reason, it's often used in hospital settings to reduce the number of surfaces that microbes can survive on (Dauvergne et al, 2021).

Example of brass patina from reddit user u/hilariouslybloody

Cool, But Why Do We Care?

Brass snaps from Hasi-Hato company in Tokyo, Japan

We here at Morning Cup Leather use only 100% brass hardware, from our snaps to our rings to our buckles. Brass coated is good, but the heft and corrosion resistance you get from solid brass is unmatched. Some of our solid brass hardware is plated in some additional material (whether that's zinc or some other metal for coloration) but is always devoid of any clear, plastic top coat so that you can experience all of the real-time benefits, both chemical and aesthetic, of a true aging brass.

The way that you use our products will reveal new and interesting colorations and properties in the brass. Left in a drawer and exposed only to air, it can develop a dark brown mottled layer, while a piece of brass that's regularly handled and exposed to hand oils will develop a dull gold luster. In the right conditions, it can even turn shades of blue and green, something that will vary depending on the part of the world you're in! In this way, the story of the leather goods you use is carried with them everywhere. Since brass is such a dynamic material, everything you do to the metal is reflected in its appearance and texture, something that we think should be celebrated.

The hardware we use is from the Hasi-Hato company, located in Tokyo. This manufacturer was selected due to their reputation for putting out high-precision snaps with remarkably tight tolerances, used in many of the highest-end leather goods from around the world. They're a bit more expensive than anything else you can get but compared to everything we tested, the difference was clear.

Oil vs Wax

Lipids describe any number of fatty, waxy, or oily compounds that are insoluble in water (and any other polar solvents). Both oils and waxes fall into this category and both are made up of chains of fatty acids. Over 70 different types of these carboxylic fatty acid chains have been discovered in nature. The main difference between waxes and oils is just whether or not they're liquid at room temperature (oils are, waxes not so much). This is based on their chemical structure but that's true for literally everything that changes phase (like water!) so it isn't as interesting to get into.

Beeswax in its raw and processed forms

Okay, I said it before but this time, seriously, WHO cares?

Hot Stuffing Drum, where oils and waxes are heated and tumbled with the tanned hides, courtesy of Wickett & Craig

These compounds matter because they're present in nearly everything related to leather and the process of crafting things from it. It starts with the hide before it's ever harvested. There are plenty of fats present in the hide while the cow is still alive. Some of these are still present following the tanning process and contribute to some of leather's unique properties.

On top of this, during the tanning process, nearly all tanneries impregnate the hides with their own proprietary blend of oils and waxes. Occasionally, a leather will be made that has its surface coated in one of these blends and then heated to the point that it absorbs all of the fatty compounds until it is saturated in a process known as hot-stuffing. This can lead to some very cool results with leathers that display a property known as 'pull-up' where it becomes lighter where the waxes and oils are physically moved out of the way where pressure is applied, similar to wringing out a towel until part of it feels dry.

It's also for this reason that applying these compounds to YOUR leather goods can be beneficial. Most lotion meant for your skin is also made up of these sorts of lipids and you can think of caring for your leather exactly the same as moisturizing your hands. Over time, areas of a leather product will lose some of their oils, either due to becoming wet and having them leeched out or just being mechanically moved to another part of the leather due to repeated wear, such as a bend point at the toe of a boot or the fold in a wallet. By applying oils and waxes in the form of leather balm or conditioner, you can replenish these and refresh your leather products. (By the way, we make our own, check it out here!)

Brain Tanning

This is an ancient process for tanning hides that is now only really used by individuals who tan as a hobby, not large-scale tanneries. That said, it uniquely uses fats to tan hides entirely naturally which is very different from all other major methods of preserving hides.

The lecithin oil contained in an animal's brain can adequately preserve rawhide when mixed into a slurry with water and spread across a skin and allowed to dry. The oils in this case break down the connective tissue in the skin before the whole thing is smoked over a fire (a process which gives brain-tanned hides a very distinct scent some compare to beef jerky). Interestingly enough (and somewhat macabrely), the brain size of almost all mammals is exactly right to tan their own hide, any bigger or smaller and the ratio would be off.

Brain Tanned deer hide smoking over a campfire

What is Patina?

The word patina comes from a Latin word referring to a shallow dish. This was incorporated into French where it began to refer to the greenish film that would develop on shallow pans made of bronze. Funny enough, because of this, 'pie' and 'patina' actually share an etymological root! Today, we know that this is the result of copper oxides forming on the surface of copper alloys, as discussed in the Brass section.

The word has expanded its definition in the modern day to refer to any type of wear incurred by a material that can be found aesthetically pleasing. Check the bottom of this page for a gallery of images of patina examples across a multitude of materials.