How Rubber Boots and Shoes are Made
The History of using natural rubber to make garden shoes and boots.
The production of rubber boots started in the mid nineteenth century after Charles Goodyear ( of car tyre fame) invented the vulcanisation process . Goodyear may have been a smart inventor but sadly he made no money out of it! In images he always looks very sad;
Rubber starts life as latex, a white sticky resin that runs out of the bark of rubber trees ( mostly that's Hevea brasiliensis trees although latex comes from other plants too ) in tropical countries such as Brazil, Malaysia, Thailand and Vietnam.
It is thought that rubber had been tapped and used to make waterproof clothing by south American indian societies for hundreds of years, and then in the early nineteenth century Charles Macintosh invented rubberized cloth to make waterproof coats....you know, those famous Mackintoshes! Check out this web site to learn how their coats are made.
The vulcanising process.
But none of his had been "vulcanised". With the growth of the automotive industry the hunt was on to find a better material to use for car tyres....and Goodyear figured out that with the addition of a few natural elements (such as volcanic sulphur from Italy) and the application of heat, that white sticky stuff could be turned into a strong, stable material that could be moulded to take the shape of all kinds of industrial products. The term "vulcanisation" was used to reflect the Roman god of Fire...Vulcan! A statue of vulcan was created by Thorvaldsen in the mid nineteenth century and is in the museum in Copenhagen if you fancy taking a look!
But Goodyear didnt apply his new vulcanising process to rain boots or wellington boots. A while later Hiram Hutchinson an american industrialist agreed to take the patent for waterproof footwear from Goodyear and worked out how to make a more user friendly product in the form of waterproof boots. If you want to read more about the origin of the Wellington boot specifically take a look at this blog on the subject of Wellies in Fashion. But back to how to manufacture footwear - many of the production steps are unchanged since that time. One way to describe the process is to compare it with making pastry!
THE PRODUCTION PROCESS FOR MAKING RUBBER SHOES AND BOOTS.
The natural latex rubber comes from the plantations where it is tapped straight from the tree, it gets coagulated and washed and pressed into sheets or blocks so it arrives at the factory looking like huge blocks of crepe rubber .
The raw rubber is put through a series of "milling" machines that work the rubber to remove all the lumps and disperse the other materials that amongst other things add colour, increased durability and flexibility.... and then, just like making pastry, the prepared rubber is rolled out into thin sheet form ready for cutting. If the boot is made up of more than one colour then the factory has to first of all produce sheets of all the different colours....and so manufacturing for Poddy & Black rubber boots with all those colours has the added complexity of getting all our colours right! Luckily we work with a brilliant factory that we have known for decades through a career in footwear, and they are great at getting the colour right first time!
The sheets are cut by hand using a metal cutting tool ( imagine a giant pastry cutter) that has the shape of the boot or style being made . Every single piece is inspected before it is used and all off-cuts or rejects go back to the start of the process to be re-used - almost nothing is wasted! There are many separate pieces of rubber in various colours that go into making a pair of Poddy and Black garden shoes or boots;
So, back to the shoe making - to assemble the boot first of all the cotton lining is sewn into a boot shaped sock and this is pulled onto the metal last or boot form.
Poddy & Black is unusual in choosing cotton for the lining as there are cheaper options ( such as polyester or nylon fabric) , but we wanted both the softness and comfort of cotton in our lined boot and also decided that using a recycled natural material was better for the environment than using an oil based textile.
Then the pre-cut raw rubber pieces are laid by hand onto the covered last. It is highly skilled work and care must be taken to position the pieces in exactly the right spot, make sure there are no unwanted bumps as the layers are built up, and above all else ensure there are no gaps between the pieces or at the joins as this would cause a leak in the finished rubber boots. At this stage more liquid latex is used as a glue to hold the pieces in the right place on the last as they could move before the vuclanising stage.
Meanwhile in another part of the factory the soles are being made. Carefully weighed pieces of raw rubber are laid into metal moulds that are made according to the design of the sole, the mould is then slipped into a heated press allowing the rubber to melt and take shape. These partially cooked soles are attached to the upper which has been made on the foot shaped last.
And finally after checking everything is ok the rubber boots on the metal lasts are loaded onto a metal trolley and rolled into the oven ( known as an autoclave) where they are "cooked" for about 35 mins reaching 170 degrees Celcius. This is ofcourse the reason why the lasts and the racks are all metal....and this is the vulcanising stage!
Now each rubber boot is cleaned, trimmed of any surplus rubber, slipped off the metal last and checked for quality - this includes immersion in a watertank to see if any air escapes as they must of course be waterproof!
And then the boots are ready waiting to be packed into our lovely recycled cardboard shoe boxes and sent by ship to the UK!
Why choose rubber over other materials for making garden shoes and boots?
As we have seen one of the reasons that rubber shoes and boots and more expensive than PVC ones is all that hand work and all those different component parts....the rubber product is hand made, while the PVC one is just an oil based polymer that gets squirted into a machine and pops out without any human input. There is a lot of evidence to suggest that using rubber is preferable to using PVC from an environmental point of view. This article concludes that rubber is a better choice if we care about the planet, and Greenpeace go further suggesting we should stop using PVC altogther.
And finally there is something wonderfully elemental about the vulcanising process of natural rubber. Its a bit like turning grass via milk into delicious cheese, or turning the fruits of the grape vine into fine wine....it is a process that man has invented or discovered, refined over time and results in a thing of beauty....we think so anyway!