Neoprene is a type of synthetic rubber made by polymerization of chloroprene invented by DuPont in 1931. Neoprene is resistant against most chemicals and can be used in a wide range of temperatures while it remains flexible. It is the best material to be used for insulation, especially insulation against temperature differences. Therefore, neoprene is the best material to be used to produce wetsuits. It can be fit tight around the body, stay flexible and protect you from hypothermia while surfing in cold waters or during long surf sessions. The main ingredient of wetsuit neoprene is the element carbon (C), which can be derived from oil. Alternatively, from more environmentally friendly limestone or other sources with high carbon content. There are many types of neoprene available with different characteristics, price, application and impact on the environment. Neoprene is also known as CR neoprene, Limestone neoprene, or Polychloroprene.
The main ingredient used in a wetsuit, about 80%, is neoprene foam. Foam is the result of the neoprene production process. Polychloroprene rubber chips are heated up, coloured black and mixed with a foaming agent. This makes the liquid neoprene foam up where it expands into a mould. After the foaming process, it is sliced in different thickness. This is when neoprene panel thicknesses are determined. Neoprene foam can be heat treated to change into single lined neoprene. Alternatively, it can be lined with a jersey on both sides as double lined neoprene. Different grades of foam have different capabilities and characteristics. For example, differences in stretch or elongation, the amount of resistance to UV and Ozone, different impact or compression strength, etc. Usually, the more flexible and softer the foam, the more high-end it is. Let’s find out more about the different neoprene types available.
CR neoprene, oil or limestone-based.
The most commonly used neoprene type in most industries is CR neoprene, also known as Chloroprene rubber, CR or Polychloroprene. A synthetic rubber produced by polymerization of chloroprene. It has similar characteristics to natural rubber but is far easier to produce on a bigger scale. Chloroprene rubber exhibits good chemical stability and maintains flexibility over a wide temperature range. We know Neoprene as the main ingredient of wetsuits, but in different grades, it can also be used in other products. For example, laptop sleeves, orthopaedic braces, electrical insulation, liquid and sheet applied elastomeric membranes. In the automotive industry its mostly used in products such as fan belts. CR neoprene can be made out of oil, which is harmful to the environment. Instead, some manufacturers use a more high-end type of CR rubber foam that is limestone-based instead of oil-based. This has far less impact on the environment.
Petrol based neoprene is the traditional method of making neoprene as invented in the 1950s. Petrol based CR neoprene is still used in a lot of wetsuits but this is much less environmentally friendly than the newer, cleaner versions of neoprene available, such as limestone neoprene.
The invention of limestone neoprene made a big impact on wetsuit manufacturing, which transformed the high-end wetsuit industry to become more durable and environmentally friendly. Some companies have different names for their more environmentally friendly neoprene. You might have heard of Japanese Yamamoto neoprene, which is used in some high-end wetsuit models. Other versions of limestone neoprene are Bioprene, made from seashells and Geoprene wetsuits. Yulex is another alternative neoprene made out of natural rubber which unfortunately has limited availability. Some brands have chosen to manufacture with limestone neoprene, which has the lowest carbon footprint in modern neoprene production. The use of limestone neoprene is an effort to make wetsuits as sustainable as possible.
In the 1960s, a new way of making neoprene was invented. The main neoprene compound remains chloroprene, but instead of using dirty petroleum-based ingredients it now uses calcium carbonate from limestone. Limestone is mainly mined and Japan where it is transformed into rubber chips. These chips are melted down in an oven and go through a chemical process. The melted substance is infused with air bubbles and baked into a block of neoprene foam. This block is then sliced in any neoprene thickness needed to make your wetsuits, ranging from 0.4mm to 10mm thickness and everything in between. The elongation, flexibility and insulation characteristics of limestone neoprene are the same or better than its predecessor petroleum-based neoprene but are way less harmful to the environment. This makes limestone neoprene one of the most flexible warm and most eco-friendly neoprene types out there.
Japan is known for its high-end neoprene production. From rubber chips to CR neoprene blocks to sliced and laminated ready to use sheets and even complete wetsuits. Denka is one of the largest limestone chips manufacturers that produce limestone rubber chips for most of the world’s neoprene sheet production. Another Japanese company Yamamoto is a manufacturer of neoprene sheets and wetsuits made out of limestone rubber chips. One of the neoprene types they produce is called Geoprene.
Natural rubber, Yulex neoprene
A completely different way of making wetsuits is using natural rubber. Locally known as caoutchouc, the material harvested from the latex saps of rubber trees. It mainly consists of polymers of the organic compound isoprene and water. Rubber trees grow in tropical areas around the world. Natural rubber is used as the main ingredient to make neoprene types like naturalprene or neoprene free Yulex Pure. These types of natural rubber neoprene still require about 25% of synthetic neoprene to be mixed into the process to enhance the lifespan, elongation, and quality to get close to CR neoprene.
SBR foam is similar to neoprene foam and can be lined with nylon or polyester lining to get the same appearance as a normal neoprene wetsuit. However, SBR foam has poor elongation capabilities and is hardly ozone or chemical resistant. This is why it is used mainly in very cheap, not very flexible summer wetsuits with flatlock stitching. Avoid any SBR wetsuits to be used as winter wetsuit.
To make Neoprene last longer, give colour to it, become more resistant to abrasion, impact, and damage during use, most wetsuits are lined. Lining refers to the inside and outside knitted and laminated finish of a wetsuit. It can be single lined or double lined. Single lined neoprene means only the inside has a knitted lining, while the outside is sealed neoprene-like mesh, smoothskin or glideskin. Double lined means both inside and outside have a knitted lining. Lining can be knitted from polyester, nylon, spandex, lycra or a combination of these materials. It can be defined by different characteristics such as soft hand feel, flexibility or elongation level, abrasion resistance such as knee pads, quick-dry functions such as plush insulation inside lining, different colours, textures, price and so on.
Double lined neoprene
Double lined neoprene is also called double nylon neoprene. After a neoprene foam has been sliced into sheets of the right thickness, it’s laminated with a stretchy fabric layer on the outside of the wetsuit. This makes wetsuits more durable and protects it against outside influences like UV and ozone. Outside lining also offers protection from fingernails cutting through the fabric when pulling on the wetsuit and sitting on the wax of your surfboard. The inside of most wetsuits is lined with an extremely flexible and soft lining that is comfortable to wear on the skin.
Single lined neoprene
Single lined neoprene also referred to as mesh, glideskin or smoothskin can be used as an outside finish of a wetsuit panel. These are the types of single lined neoprene that have a heat-sealed outside skin surface which seals the neoprene foam to make it durable and water repellant. This creates a fine mesh texture on the surface. The finer the mesh, the smoother and shinier the skin. Mesh is often less flexible and has a matt textured finish, while glideskin and smoothskin have a more shiny and smooth surface.
These types of neoprene are often used on the chest and back panels of a wetsuit to keep you warmer in windy and cold conditions. The sealed material surface makes the water droplets run down faster without being absorbed in the lining, this protects you against windchill and makes it warmer than double lined neoprene. The inside of single lined panels is lined with a nylon or polyester knitted lining for comfort to the skin. This lining can be plush or quickdry lining on more high-end wetsuits.
Neoprene inside lining is the knitted and laminated finish on the inside of a wetsuit. Lining can be made from polyester, nylon, spandex, lycra or a combination of these materials. Inside lining can be defined by different characteristics. For example, soft hand-feel, flexibility or elongation percentage. Other differences can be quickdry functions, such as plush insulation inside lining, different colours, textures, price and so on.
The quality of neoprene can be determined by a few variables. Each neoprene foam type has its own characteristics that make them suitable for various applications. For surface water sports wetsuits the main variables to look for are high thermal insulation, mainly determined by the neoprene thickness used, high elongation percentage and excellent resistance against UV and Ozone. Diving wetsuits require different characteristics. For example, a good compression rating to prevent neoprene from collapsing under pressure the deeper you dive.
Thermal insulation is the reduction of heat transfer between objects with different temperatures. In the case of a wetsuit, it refers to the capability of a wetsuit to protect you from the cold water and wind. This results in retaining your body heat inside the wetsuit. Neoprene is a good insulator due to the air bubbles inside the neoprene foam. Therefore, the thicker the neoprene foam, the better the insulation and warmer you feel in cold water. Neoprene has low energy conductive properties, which limit heat flow. This is why it’s commonly used as insulation material in different applications.
Elongation is the percentage of the stretch of neoprene raw foam. It is measured before the lining is laminated onto the foam. The more flexible the foam, the higher the elongation percentage. Less flexible and stiffer foam has about 150-200% elongation. Soft, very flexible and usually lighter foam sits around the 350~400% mark.
Ozone and UV resistance
Neoprene foam deteriorates over time, it becomes brittle and it will start cracking. Therefore, the longer this takes, the better the neoprene foam quality. The main factor that determines this is the amount of resistance against Ozone in the atmosphere and UV rays from the sun. So to increase your wetsuit lifespan, never leave your wetsuit to dry in direct sunlight.
PAHs are compounds with a potential increased risk of certain diseases and recently found in research that they exist not only in tire products but also in all rubber products. Examples of toxic PAHs are Acenaphthene, Acenaphthylene, Anthracene, Fluoranthene, Fluorene, Phenanthrene, Pyrene, Chrysene, and Dibenzo[a,h] anthracene.
The German Committee for Product Safety, aligned with the REACH Annex XVII PAHs, has determined the requirements for 18 PAHs permissible limits in consumer goods. SRFACE neoprene has been categorized as Category 2 (Other products) which most parameters out of 18 must be detected under 0.5ppm.
So, don’t worry, no harmful PAHs can be found in SRFACE wetsuits. We only sell products that are REACH SVHC List Compliant. Read more here.
When buying a wetsuit, always look at the type of neoprene used that matches your needs. However, don’t be scared or too impressed by some of the names brands call their neoprene, it all comes down to what’s inside.