Natural vs Synthetic Rubber Watch Straps

Rubber watch straps are growing more and more in popularity.  Whereas previously they were the domain of the divers and water sports enthusiasts due to their resistance to deterioration in salt water.  Now the straps are worn as a practical and stylish alternative to a leather watch strap or metal bracelet.

With  the flexibility of the the moulds being able to produce all sorts of shapes colours and patterns, the option are endless.  

Hirsch have designed a whole premium Performance Strap Range that redefines the rubber watch strap, mixing it with other materials and colours to increase its versatility. Hirsch also used an innovative underside pattern on the strap to wick away any moisture that may occur there.

Performance strap analysis

When many people talk about "rubber", they don't usually specify what kind. There are many different kinds of rubber, but they all fall into two broad types:

Natural rubber (latex—grown from plants)
Synthetic rubber (made artificially in a chemical plant or laboratory).

Although natural rubber and synthetic rubbers are similar in some ways, they're made by entirely different processes and chemically quite different.

Natural Rubber is made from a runny, milky white liquid called latex that oozes from certain plants when you cut into them. There are something like 200 plants in the world that produce latex, but over 99 percent of the world's natural rubber is made from the latex that comes from a tree species called Hevea brasiliensis, widely known as the rubber tree. This latex is about one third water and one third rubber particles held in a form known as a colloidal suspension. the Latex is made of many thousands of basic C5H8 units (the monomer of isoprene) loosely joined to make long, tangled chains. These chains of molecules can be pulled apart and untangled fairly easily, but they spring straight back together if you release them—and that's what makes rubber elastic.

Latex extraction from the Rubber Tree


Synthetic Rubbers are made in chemical plants using petrochemicals as their starting point. One of the first (and still one of the best known) is neoprene, made by reacting together acetylene and hydrochloric acid. Emulsion rubber, another synthetic rubber, is widely used for making vehicle tires 


Vulcanization of Natural rubber 

Rubber—the kind you get from a tree—starts off as white and runny latex. Even when it's set into a product, this latex-based, natural rubber is very squashy, pretty smelly, and not very useful. The kind of rubber you see in the world around you, in things like car and bicycle tires, is vulcanized: cooked with sulfur (and often other additives) to make it harder, stronger, and longer lasting.

So what's the difference between raw, latex rubber and cooked, vulcanized rubber? In its natural state, the molecules in rubber are long chains that are tangled up and only weakly linked together. It's relatively easy to pull them apart—and that's why latex rubber is so stretchy and elastic. When latex is vulcanized, the added sulfur atoms help to form extra bonds between the rubber molecules, which are known as cross-links. These work a bit like the trusses you see on a bridge, tying the molecules together and making them much harder to pull apart.

When natural rubber is cooked with sulfur, the sulfur atoms form extra cross-links (shown here as yellow bars) "bolting" the molecules together and making them much harder to pull apart. This process is called vulcanization and it makes the strong, durable, black rubber we see on things like car tires.

Today, most natural rubber still comes from the Far East, while Russia and its former republics, France, Germany, and the United States are among the world's leading producers of synthetic rubber. The world's largest single source of latex rubber is the Harbel Rubber Plantation near Monrovia in Liberia, established in the 1920s and 1930s by the Firestone tire company.


So which is better for a watch strap Natural or Silicone?

There are pros and cons for both....

Silicone and rubber watch straps can be much softer and more flexible than resin watch straps. Unlike resin straps which can split if flexed too much, silicon and rubber straps are very flexible and will not split. However they have a lower tensile strength and are not so resistant to heat and light.

Natural resin or Caoutchouc as it is also known, is naturally hypo-allergenic dimensionally stable, tear-proof and resistant to external influences, such as UV light, chemicals, extreme heat or cold.

At the end of the day it comes down to personal preference.  We stock both types in varying budgets.

A bright yellow ISOfrane strap 

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1 comment

  • Charles : August 17, 2017

    All made some sort of sense until you suddenly mention resin and silicone and I am back to being confused. What is resin? Is silicone synthetic then?

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