• Safety hats are often required at the workplace.yellow construction hat image by Peter Baxter from Fotolia.com
  
  Safety hats, or hardhats, have been a fixture at labor work sites dating as far back as the Hoover Dam project in 1931. They were originally patented in 1919 by Edward Dickinson Bullard, when they were made of canvas and glue. Bullard also developed the internal suspension which creates space between your head and the helmet, making it safer. Since the early 1900s the safety hat has been redesigned using different materials.
  
  

Aluminum

• Aluminum was first introduced as a hardhat material in 1938. It was durable and lightweight, but had one disadvantage: aluminum conducts electricity. As a result, the helmets were not used at sites where electrical hazards could be present.
  
  

Fiberglass

• In the 1940s hardhat manufacturers began using fiberglass. Unlike aluminum, fiberglass can insulate against high voltages. It is also resistant to high heat and is difficult to break. In addition to being resistant to scuffs and discoloration, fiberglass also sheds rain in such a way that there is no accumulation of large drops at the edge of the hat. Fiberglass is lightweight and makes for hardhats that are better balanced so they stay on when you tilt your head at extreme angles.
  
  

Thermoplastics

• A less costly alternative to fiberglass, introduced in the 1950s, is thermoplastic, which is injected into molds to create safety hats. The most widely used thermoplastic for hardhats is polyethylene plastic. The material is easy to mold, and it's lightweight, non-conductive to electrical current, and durable. An ultra-violet inhibitor used to treat the plastic increases its longevity in outdoor environments.
  
  

Internal Suspension

• The internal suspension of a hardhat is also made from plastic material. The design is such that the suspension legs are able to absorb impact without breaking, so that the energy of the impact is reduced and is distributed evenly throughout the suspension.
  
  

Material Life

• Hardhat materials are subject to deterioration by environmental factors such as UV rays, excessive heat and cold. They should be stored out of direct light. Inspect the shell and internal suspension regularly for signs of wear, and replace immediately if the hat has sustained any impact. The materials hardhats are made of are designed to protect you only once. Even if there has been no impact, Bullard Company recommends that hard hats be replaced regularly; replace the internal suspension should every 12 months. You can keep the shell for up to five years if it has not been exposed to excessive elements. If it has, replace after two years.