Sometimes safety glasses are confused with other types of glasses that may provide some protection for the eye – but safety glasses are a spectacles category all to their own, and it is important to understand the differences and distinguish between them and normal glasses or spectacles. The first safety lenses for glasses were laminated.  They were made up of two sheets of glass with a lamina in the middle, the three stuck together with a type of cement between the contact surfaces.  The laminate was usually made of cellulose acetate or xylonite.   The famous trade names of these lenses were  Salvoc, Motex and Triplex.

 This laminated principle was also widely used in the manufacture of car windscreens and goggles for motor cyclists and aviators;  Biggles, of course, being the prime exponent of this type of eyewear.

It was not until the late 1950’s that glass toughened lenses appeared on the market. They had some advantages over the laminated lenses.  One being that there was no lamina to deteriorate. This was a common fault with laminated lenses although it was sometimes possible to have them relaminated, thus saving the cost of new lenses.  This concept is quite incomprehensible in today’s world, as indeed is the idea of having used lenses repolished if they become scratched.

Glass lenses were toughened by a case hardening process involving heating the lenses and rapidly cooling them with cold air.  Much later an alternative method of case hardening was devised which was a chemical process.

All toughened lenses, on completion of the toughening had to pass the drop ball test.  This consisted of dropping a steel ball of given weight, dropped from a specified height (usually down a glass tube to make sure it hit the target correctly) on to the lens which had to placed on a piece of rubber of the correct standard of thickness and density. 

The lens itself had to be of a certain thickness which was generally thicker than standard lenses.  There was a higher grade of toughened lenses known as industrial toughened.  These lenses had to be thicker again for the same prescription as ordinary toughened lenses and had to have a more severe toughening process.  Consequently the drop ball test required a heavier steel ball, dropped from a greater height.

Nowadays, things are a little simpler with plastics lenses and the introduction polycarbonate makes it relatively to easy comply with the higher grades of impact resistance. 

Most suppliers nowadays find it easier to use a specialist safety company to meet their requirements and many industrial companies have their own arrangements with safety spectacle companies. 

Some companies specify to their employees that safety spectacles supplied by them may only be worn for their company duties. Is there any enforcement agency to police this rule?  Supposing one feckless employee turned up at the works’ annual dinner in black tie and safety glasses; is it incumbent on his fellow workers to bring it to the attention of the safety officer seated at top table?

well……the top 5 for now anyway, we will come up with the other 5 (or if you have an opinion ?)

1.       Time is short : who has time to shop for glasses walking around town ? Let’s see – about a million glasses styles online at cheap prices, or about 1% of the same selection for at least twice the price……..hmm……………

2.       Did I mention the million styles of glasses online versus a few dozen in the shop ?

3.       They are so cheap online, you can have a pair for every outfit, rather than have glasses that clash with your bodice

4.       When you shop online for cheap glasses, there is nobody following you around trying to sell you expensive glasses that you don’t need

5.       Did I mention that glasses online are cheap – and you can save literally 100’s of £’s ?

Do you have any opinions or experience about buying your glasses online ? Care to share them so we can put the next five reasons to shop online for glasses here ?