Knowing how to care for your boots begins with knowing something about the materials and technologies used in its construction. The following is a basic overview of the common materials and technologies used in boot and shoe making. For more on extending the life of your boots, or if you’re already familiar with your boots’ materials and technologies, jump to our page on boot care.
Leather is a natural material derived from ‘tanning’ and ‘splitting’ animal skins, usually cattle hides, but also exotics like ostrich and alligator which are commonly used on custom western boots. Not all leathers are created equally, however, and the quality, durability, and flexibility of the leather depends greatly on how the hides are treated during and after the tanning process. The general process of tanning and splitting cattle hides is covered below:
The tanning process entails soaking raw animal hides in a combination of natural oils, tanning agents, and dyes. Hides are tanned in order to stabilize the proteins in the leather and reduce the likelihood of material break-down and rot. After the hides have been tanned, they are removed from the tanning drums and are then dried, rolled, stretched, and split.
The process by which a hide is made to a specific thickness for its specific application is called ‘splitting.’ The workability and durability of leather depends on its thickness. Leather thickness is usually measured in ounces. Most leathers used for boot and shoe-making are between 4 and 7 ounces (approximately 1/16? – 1/8? thick). Split leather produces leather variants, like suede and nubuck, which reveal the fibrous portions of the hide. Full grain leathers are not split and are generally more durable and breathable but take longer to break in. Split hides are generally lighter and more flexible but are less durable.
Rubber boots come in many different styles to suit a variety of applications, most of which entail especially wet or cold conditions. In their most basic form, rubber boots may only consist of one or two pieces: an upper and an outsole. Some rubber boots incorporate a safety toe cap. Rubber hunting boots generally have more features, such as aggressive outsoles, neoprene liners, insulation, scent-lock, and a whole array of fit features and comfort technologies.
Neoprene is a 100% waterproof material with thermal properties. The same material used to make wetsuits, neoprene boots are often pac style (pull on). Neoprene boots are often used in cold conditions and temperature ratings are generally determined by the thickness of the neoprene in millimeters.
PU stands for Polyurethane and, like rubber and neoprene, is 100% waterproof. PU is quickly becoming popular in the oil and gas industries for its superior resistance to chemicals and corrosion. PU is generally lighter than rubber and neoprene and is more resilient to compression due to long-term wear and cracking due to constant flexing.
The complete list of synthetic materials is too long to cover here, so only a few important materials will be discussed. Nylon and rayon are occasionally incorporated as individual panels on leather boots, either as an accent (i.e. camouflage patterns), to improve breathability, or to simply cut the cost of an otherwise entirely leather boot. Cordura, a popular material usually in the form of nylon, is a name brand line of abrasion and tear resistant fabrics developed by the DuPont Company, and is featured on everything from hunting boots, duty boots, and boots used by the military.
‘Waterproof’ specifically refers to a membrane system that prevents water and outside moisture from permeating the boot. Waterproof membranes in the form of a fabric bootie are sandwiched between the upper and the liner when the boot is constructed. Waterproofing is the most durable and reliable of the systems. Gore-Tex is a familiar and trusted name brand waterproof system, though many other name brands exist. Gore has been a pioneer in the field of technical fabrics for decades and continues to be. Many boot manufactures incorporate their own proprietary waterproof systems.
‘Water-resistant’ generally refers to a topical application that allows water to bead and roll off the surface of the boot. Oiled leather, laminated leather, silicone sprays, and pastes are examples of water-resistant treatments.
‘Seam sealing’ is the process by which stitched portions of the boot are sealed with seam sealing tape or adhesive, providing a water-repellent barrier along major seams which may be exposed to water or moisture.
Thinsulate, Primaloft, and Thermolite are examples of synthetic insulators. These materials offer warmth and breathability without the bulk that is often associated with traditional materials, such as felt and shearling. These materials are often rated by weight (i.e. grams per square meter).
Felt, often in the form of a removable liner, is a traditional method of keeping feet their warmest. The temperature rating of felt is often determined by thickness (usually in millimeters). Shearling, or wool, is another traditional material used to insulate footwear. The temperature rating of shearling is also determined by its thickness. Shearling naturally regulates temperature and perspiration, is breathable, and naturally antimicrobial. The efficiency of these materials depends on a few important factors: the materials used, proper fit, and activity level. Below is an chart indicating the appropriate amount of insulation per conditions and should only be used as an approximation.
0-200 grams / 3.5mm neoprene: Spring/Fall
400-800 grams / 5-7mm neoprene: medium activity/cool; high activity/cold
1000-2000 grams / 9mm neoprene: low activity/bitter; motionless/cold
Thanks to constant advancements in chemistry and product design, there are just about as many outsoles as there are styles of boots. Only a few of the most popular materials used in outsole construction will be covered here.
In 1935, following the tragic death of six mountaineers, Italian and founder of Vibram, Vitale Bramani, begins designing what will become the world’s first lug outsole, utilizing vulcanized rubber. Vulcanization is the chemical process by which natural rubber is converted into a more durable material by the addition of curatives and accelerators. These additives form cross-links, stabilizing the material and making it more resistant to abrasion and improving its ability to maintain traction on a variety of surfaces.
TPU stands for Thermoplastic Polyurethane. The mechanical properties of TPU include elasticity and resistance to oil, slip, and abrasion. TPU is generally transparent.
Like TPU, PU is a material used for its resistance to oil, slip, and abrasion, but also for its superior resistance to chemicals. PU outsoles are featured on many specialty boots used in the oil and gas industries where exposure to chemicals is a common occurrence.