Comfort, Quality, Durability: Keys to Effective Protection
Not all occupational footwear that is protective involves formal ASTM ratings and testing procedures. Three of the most important of these are waterproof, insulated, and slip-resistant footwear.
- By Roger Huard
- Apr 01, 2016
The idea of foot protection can cover different areas when one is talking about occupation footwear. Sources of such differences are the differences in the kinds of work that fall within the general category of occupational footwear. The standard features of protective footwear and the ones most likely to come to mind are the ones that are required by employers or are considered prudent to have within a given work environment. Generally, these types of protection are accompanied by the ASTM International rating that signifies that the footwear meets or exceeds specific measures when tested under controlled laboratory conditions.
The major types of protection covered by ASTM ratings are:
- Safety-toe. All safety-toe footwear must meet or exceed the specific ASTM measures for impact and compression. The caps themselves can vary in terms of material composition, the most popular type being the traditional steel cap. However, both aluminum alloy and composite (plastic resin) caps are used because they are less heavy, while composite caps have the added benefit of not conducting heat or cold, thus enhancing internal foot comfort. Recent developments in nanotechnology that features carbon fiber have made it possible to make composite caps that are even lighter and more comfortable because they are less bulky.
- Met guard. Footwear that has a met guard built onto (external) or into (internal) them are rated by ASTM to help protect the top and particularly metatarsal areas of the foot from the drop hazards. Typical occupations that tend to employ met guard footwear are foundry workers, pipefitters, and even some types of warehouse jobs. External met guards are the traditional and original form of this kind of protection and tend to be bulky, however, with the more advanced types of polymers, met guards that were ASTM rated could be built inside the footwear, giving the wearer a less bulky and more comfortable fit.
- Electrical. Many occupational types of footwear come with an electrical rating. The majority of these are rated EH for electrical hazard. This type of footwear is designed to reduce the danger due to accidental contact with live electrical current (in effect, the footwear inhibits grounding of the electrical current). More specialized than EH footwear is the SD rating, which seeks to reduce the accumulation of static electricity by conducting the electrical charge to the ground in a regulated manner while still protecting the wearer of electrical hazards. This type of footwear is typically used in occupations where the discharge of static buildup can cause problems to machinery (assembly line robotics) or individuals (paint booth operators). Finally, and perhaps most rare, is footwear that is rated CD for conductive. In this case, one is enhancing the conductivity of the footwear so that any static electrical building up is grounded and discharged. Places for this type of footwear are ammunition and/or powder plants.
- Puncture resistance. Finally, there are types of protective footwear that are ASTM rated for PR—puncture resistance. The goal here is to reduce the danger of any puncture wounds to the bottom of foot, such as stepping on an exposed nailed. Footwear of this type generally has a protective steel plate or a layered aramid fabric insole. The steel option is the more original and traditional type of protection. The layered fabrics offer the same protection with less weight and greater flexibility.
Not all occupational footwear that is protective involves formal ASTM ratings and testing procedures. Three of the most important of these are waterproof, insulated and slip-resistant footwear.
- Waterproof. The ability to build effective non-rubber waterproof footwear is a relative new development. The central breakthrough in this area came with the invention of reliable waterproof membranes that can be built into the footwear. The first and most familiar of these is the Goretex membrane. These days, there are a variety of reliable waterproof membranes in the market. It is important to note, however, that waterproof protection as such is not regulated in the United States by any agreed-upon standards such as ASTM ratings. It is important to find out as much about the footwear as possible whether from a retailer, website, or product reviews.
- Insulation. Boots that provide insulation against cold environments can be effective. Usually they are insulated with a branded insulation material such as Thinsulate or Primaloft or use a generic or proprietary material. There are a couple of considerations one should look at when buying insulated boots. What will be the end use? Insulated boots come in a variety of insulation levels, but sometimes they are not expressed in the gram weight of the material. Lighter levels are more appropriate for occupations where there is regular and constant activity. Higher levels are recommended if the wearer will be less active and more stationary. The other consideration is that if the footwear is going to have a safety toe in it, a composite cap is recommended because it will not conduct cold, as steel will.
- Slip resistance. There is greater and greater interest within the occupational safety field in protecting individuals from slipping in the workplace. These concerns have the most application to environments that have smooth walking surfaces, especially ones that are or can become wet. Generally speaking, protective footwear that is labelled SR is usually built to enhance traction and reduce slippage on smooth and or slick surfaces. Much as with the waterproof designations, there is no formal standard, nor is there an agreed-upon test method in the United States that defines SR. Informally speaking, the litmus test of an SR sole in the USA has been a .4 result on a Mark II testing for oily-wet surfaces. Most reputable manufacturers of SR footwear either list or provide slip resistance test results. Achieving good SR results is normally a function of a combination of using specially formulated slip resistant compound (usually but not always rubber based) and outsole design (surface contact, texture, and leading edges being important).
These are the basic types of footwear protection. It should also be said that two other components are relevant to this topic. One is the overall comfort of the footwear. Though not related directly to safety or protection it needs to be noted that with advances in modern materials and shoe making one does not have to trade complete comfort for protection. Finally, factors that relate directly to footwear protection are quality and durability. All of the types of protection we have talked about require that the piece of footwear is in "working" condition. Wear and tear eventually compromises the integrity of all protective footwear. Knowing the right protection for your needs, coupled with considerations about comfort, durability, and quality, will create the best conditions for an informed choice about what footwear to buy.
This article originally appeared in the April 2016 issue of Occupational Health & Safety.