Glass

There are many factors that influence the performance of glassware in a public envionment and each venue needs to be aware of the type of drinking vessel that is best suited to its needs. Often the performance of a glass is based on the following factors:


  • Glass treatment (rim, foot or fully toughened)
  • Material (quality, finish and resistance)
  • Glass thickness (even distribution and weight)
  • Design (complexity)

While various names are used in the marketplace, the three core terms used to describe glassware are:


  • Fully toughened/tempered
  • Rim or foot toughened/tempered
  • Annealed glass (normal drinkware)

Toughing it out

The terminology is often confusing and the word 'toughened' is often used indiscriminately. The way in which these differently heat treated glasses break is the key to their injury potential.

A rule of thumb is that 'non-toughened' glassware breaks into larger pieces that can take the form of shards, which can cause a severe cutting or slashing injury when be handled carelessly or as a weapon, while 'toughened' glass breaks into smaller, safer cubes similar to the glass used in bus shelters or side windows in cars.  This is usually the case, but as noted above, level of treatment, material and design can be factors that impact on the breakage pattern of a glass. 

A toughened product is obtained by applying intense heat followed by even and rapid cooling of the glass.  This process changes the stress levels within the body of the glass creating a nut like shell to the outer of a fully toughened glass or a localised strengthened band for rim/foot toughened items.

Over time the stresses within the glass relax and thus the strength of the item is reduced, however, the overall performance and lifespan of a toughened glass is considerably longer than that of a comparable non treated glass.  When the toughening process relaxes the breakage pattern can be similar or a mixture of cubed, larger pieces and shards.

In annealed and rim toughened glassware, the glass breaks into larger pieces and tends to be localised to a general area.  By contrast, a fully toughened glass breaks into smaller pieces that are spread across a greater distance.  On one hand, larger pieces mean it is easier to ind and remove broken glass, on the other there is a potential for misuse.  It is recommended that any area that has experienced a breakage is correctly cleaned, especially where food is being served.

Disposal

In common with all waste streams, it is important that pint glass materials are disposed of correctly. Glass is readily collected and recycled.

Resources

Effectiveness of toughened glassware in terms of reducing injury in bars: a randomised controlled trial, pint glasses were replaced with with annealed or toughened glassware. Results indicate that the toughened type caused more injury than annealed.