The word “sole” is Latin for soil or ground.
The sole is designed to give the shoe immense durability, even after being scraped over the ground for countless times.
It also must be able to generate enough friction between the shoe and the ground, enabling the user to walk and move around using the shoes.
Shoe soles may be of a simple, one-layer type or may be constructed using multiple layers is an advanced way.
They are made from various materials like natural rubber, leather, polyurethane and PVC compounds.
We will discuss the classification based on each type in the article
Types of Shoe Soles Based on Material
One of the most important aspects of the shoe sole is the material. Material not only provides the look and feel but also defines where the shoe should ideally be used –
Leather is the age-old choice for developing shoe soles.
Leather is soft, flexible, tough and provides enough ventilation for the feet and hence is a very popular material used to make shoe soles.
However, the maintenance of leather soles is very difficult.
Leather tends to get dry and brittle when exposed to heat and it can also shrink when wet. Moreover, leather is an expensive choice for a shoe sole.
Rubber is another popular material used for making shoe soles.
Shoes that use a rubber sole are marked with the letters RU.
Rubber soles are desirable because rubber is very resistant to abrasion. It also is very flexible and waterproof.
However, shoes that use a rubber sole tend to be very heavy.
Polyvinyl chloride, or PVC, is a good synthetic material used for making the shoe soles. PVC is a good substitute for leather as it is very cost-effective.
PVC is also known for being very strong and resilient to abrasion, and hence it is used for developing durable shoe soles.
PVC, being a thermoplastic, is a good insulator and is useful for maintaining warmth within the shoe.
PVC shoe soles are also good shock absorbers and they are resistant to attacks from chemicals.
Lastly, PVC is flexible can be easily molded into a variety of shapes according to convenience.
PVC soles are commonly built for casual shoes, sandals, and other footwear.
However, PVC soles do not offer good ventilation to the shoe or have a good texture. Their anti-slip performance is also very poor.
PVC soles are also not a very environment-friendly option for a shoe sole, due to the fact they are not biodegradable and very expensive to recycle.
EVA stands for ethylene-vinyl acetate, a synthetic material that is known for being resistant to attacks by water and other chemicals.
Also, its most important property is that it has a very high shock absorption property.
EVA shoe soles are commonly used in running shoes and other heavy-duty shoes due to their good shock-absorbing capacity, anti-vibration property, elasticity, and lightweight.
They are also widely in safety shoes as well.
EVA ensures that the sole of the shoe fits snugly onto the foot of the wearer and is thus also used as a cushioning material.
EVA is also used in building the insoles, midsole and the lining of the shoe.
Thermoplastic rubber, or TRP, is another common material used for creating shoe soles.
TRP is obtained from molding and compounding rubber.
TRP shoe soles are good shock absorbers and provide enough friction to be anti-slip soles. They are long-lasting and flexible.
However, TRP soles are not very comfortable.
TRP soles are used in hiking boots and outdoor shoes.
PU stands for polyurethane, a material that is tough, resilient and waterproof. It is a dense foam-like material that provides good cushioning to the feet.
A PU outsole is very durable and affordable. Also, PU soles absorb shocks very well.
PU soles can be worn for hours as they provide comfort to the wearer of the shoe. PU soles are used in everyday shoes and also in safety footwear.
There are several types of PU too.
- TPU is produced in a very different way than PU. They can be molded and remolded many times, unlike the normal PU. It is especially sturdy and resistant to wear and tear. BPU or blocked polyurethane is also very similar to TPU.
- Polyester polyols, another subset of PU, withstands high temperatures while the polyether polyols do not get discolored or break down easily.
The drawback of PU shoes is that it can become dry and brittle very easily when exposed to too much light or heat.
ABS stands for acrylonitrile butadiene styrene. It is a relatively new material in the market that is being used for making shoe soles.
ABS shoe soles are very durable, tough and resilient. They are, therefore, widely used in running shoes and other sports shoes.
They are also not toxic in nature and very safe to wear.
The downside of ABS soles is that they are not very adaptive with the weather. Hot weather can cause deformation in the shoe soles.
Cork is a soft material extracted from cork trees that is mixed with rubber to produce the cork sole.
Cork soles are snug and can provide a custom fit to the user.
Cork soles are also very shock-absorbent.
The cork sole is very comfortable and the wearer can stand for a long time without the sole hindering him/her.
Cork soles do not have any grooves or treads etched on their surface; hence nothing will stick onto them.
Other materials that are used to make shoe soles are nylon, Kevlar and carbon fiber.
Based on the Sole Shape
Another way we can classify soles is the shape. Based on the usage and requirement, shoe soles are designed in various different designs –
Lug soles are typically thick rubber soles that have deep indentations called lugs.
These indentations are arranged in a specific pattern such as to help increase the friction between the shoe and the ground.
Lug soles improve the shoe’s traction, thus making it slip-resistant and weather-resistant. Hence, these soles are very common in hiking boots and other outdoor shoes.
Lug soles tend to accumulate dirt in between the lugs and hence have to be cleaned frequently.
Christy soles are made of blown rubber.
They are lightweight soles which also provide good traction to the shoe. They are also known to add to the height of the shoe.
Some defining properties of a Christy sole are that they possess ripple patterns on their surface and they do not highlight the heel of the shoe in any way.
Christy soles are not as reliable as lug soles in case of being used in difficult terrains.
Camp soles come made of rubber and covered with studs all over their surface. The studs help the sole to improve its traction.
They are also light in weight and are very flexible.
It goes without saying how important it is to wear a shoe with the right kind of sole otherwise you may experience discomfort in your feet.
We hope that this article would have helped you to understand the different types of soles available, their pros and cons.
Do share your thoughts on the article or feel free to ask us queries in the comments below.