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THE NOT-SO-HUMBLE GUMBOOT

21st Aug 2007

Gumboots are a surprisingly diverse group of products, and selection is not always a straightforward process. Almost all gumboots sold in SA are locally made, and there are now six mainstream manufacturers. Imports have not, so far, been successful, because gumboot manufacturing is capital- rather than labour-intensive, and because the raw materials – PVC and rubber – are international commodities, costing much the same everywhere. Finally, because of their bulk relative to their value, they have mostly been uneconomic to ship.

Growth in demand – real and perceived – has led to a considerable increase in capacity, both through new manufacturers and upgrading of existing plants. It is estimated that total capacity is now about 130,000 – 140,000 pairs of PVC gumboots/week if all machines are working to rated capacity, two shifts/day, five days a week. The actual market is thought to be 80,000 pairs/week.

Rubber gumboot production is only 3,000 pairs/week, which more or less matches current demand. The growth in competition has kept prices keen, but it has also persuaded manufacturers to develop new products, and this is likely to accelerate, especially in terms of comfort and greater protection.

Protective devices: The first division is between protective and basic work gumboots.
Protective gumboots will have a minimum of a steel toecap, and most will also have a steel insole moulded into the boot. It’s worth checking that both devices are built into the boots you’re buying, because injuries come from all directions.
‘Metatarsal protection’ – usually an additional layer added to the top of the boot, between the inside edge of the toecap and the shaft of the boot – is becoming increasingly important as safety-consciousness increases. Work gumboots have none of these protective devices.

Materials: Gumboots are available in four basic materials – virgin PVC, a blend of virgin and recycled PVC, a blend of PVC and nitrile rubber, and natural rubber. All of these are further available in various formulations, depending on additives, mostly to reach various price points, and sometimes to achieve different properties.

PVC in its various forms is compounded by combining PVC resin with a variety of additives to achieve different properties. The most notable additives are plasticisers, to increase flexibility (PVC in its natural state is a rigid material), stabilisers, and pigments.

While a couple of the gumboot companies have their own compounding plants, most buy from independent compounders.
Though boots containing recycled PVC are cheaper, they are available in only one colour – black. As far as price goes, however, there is a rider. Most scrap comes from recycled cable, which is a more rigid form of PVC than is suitable for gumboots. To make it more flexible, the compounder must reconstitute with plasticiser and other additives.

Since the prices of reclaimed PVC and plasticisers fluctuate considerably, the PVC compounders either have to have flexible price lists or flexible formulations, with varying proportions of PVC reclaim and plasticiser. While the bigger compounders can’t afford to deviate from agreed limits, there are “all sorts of guys out there making all sorts of qualities”, according to one manufacturer.
From the end user’s perspective, virgin PVC offers two advantages and one disadvantage – it can be made in almost any colour, and there’s a greater guarantee of consistent performance. The disadvantage is that, even with fluctuating scrap prices, virgin PVC is almost always going to be more expensive.

In areas where gumboots will be exposed to oils or acids – that includes most mines – PVC is blended with nitrile rubber. The most common blend in SA is ’25 part’ (25% of resin content). European standards demand a ’35 part’ formula, and some SA buyers specify the same.
Natural rubber is regarded as the premier gumboot material in terms of durability, and abrasion-, cut-, oil- and acid-resistance, and it offers the best insulation against heat and cold.
It is also the most expensive, though the gap between rubber and the various PVC options varies with international feedstock prices. Like PVC, it can also be formulated to increase or decrease hardness and wearing properties.

Rubber has two disadvantages – it is heavier, and it is generally available only in black, limiting what can be done to enhance its aesthetics. Also, worn-out rubber gumboots can’t be recycled – which will be an increasingly important consideration for all products.

Thickness: This can vary, and it impacts on price AND durability. Since gumboots are fully moulded, wall and sole thickness are determined by the mould design. A well-designed boot will keep mass to a minimum by optimising PVC (or rubber) dispersion in the boot – thinner where flexibility is required, thicker where there is a need for protection and durability. Since steel toecaps and insoles have to be encased by the PVC or rubber, there is seldom a problem with the thickness of safety gumboots. In the general work wear market, however, thinner (and lighter) gumboots are offered, but the penalty is reduced durability and protection.

Height: The standard gumboot is calf length. Shorter boots are more comfortable, but less protective. In many cases, manufacturers simply cut the boot to a shorter height, rather than using a different mould. The PVC off cuts are recycled.

Applications: Gumboots can be used in just about any work situation – from domestic to heavy industry – but they reign supreme in any situation where there is constant exposure to water or other fluids, and the more polluted they are, the more suitable gumboots are by comparison with leather boots. It’s not that leather boots can’t be used in those situations, but they need to be cleaned daily – and dried regularly – to survive, where gumboots don’t. At one time, rubber over-boots for leather boots were available.
The most limiting factor for gumboots isn’t performance but perception – where gumboots are seen as ‘labourers’ boots’, leather is for management (i.e. people who don’t get their footwear dirty).
Except in particular conditions, like mines, smelters and heavy engineering works, which type of gumboot to choose depends on the buyer’s view of price vs. durability. In heavy, hardwearing applications, the choice is between PVC/nitrile and natural rubber. For light duty, where appearance isn’t a factor, virgin PVC/reclaim mixes are first choice, and for light duty where appearance is an issue (in food processing areas, or where the public can see workers), virgin PVC is the material of choice.

 

 

 

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