Liquid Crystal (also used in some computer screens, calculators and wrist watches) was used to prevent the temporary blindness that occurs after a nuclear explosion. The use of this technology in welding first occurred in the 1980s but has not been universally accepted. This was due to lack of knowledge, fear of electronic failure, previous bad experiences, different performance standards than expected, and cost.

How do they work?

The auto darkening welding lenses use liquid crystal to stop visible light. This works in a similar way to the way Venetian blinds stop light from entering a room. Venetian blinds close by changing the position of the slats by 90O. An Auto Darkening Filter stops most visible light from reaching the eyes by changing the position of the “shutters” by 90O.

Auto Darkening Filters have several layers of liquid crystal, similar to rows of Venetian blinds placed one behind another with an additional glass filter that blocks out damaging ultra-violet and infra-red rays at all times. The switching of the liquid crystal stops the visible light. Should an Auto Darkening Filter not change, the individual would see a flash of bright light. This light would not contain any damaging IR/UV rays. The experience is similar to having a flash bulb flashed in your eyes.

Article continues below…

Switching Speed – A Jackson Advantage

Switching speed is one of the most important performance attributes of an Auto Darkening welding filter. Jackson Auto Darkening Filter products for welding feature patented surface mode liquid crystal technology, the fastest switching liquid crystal technology available in the world. Every Jackson surface mode filter switches from light to dark in less than 100 millionths of a second.

Dr David H Sliney, US Army Environmental Hygiene Agency, said “Switching speed is crucial, since it gives the best clue to the really important measure of how much light will enter the eye when the arc is struck as compared to wearing a fixed filter of the same working shade number.”

Dr Sliney and Dorothy Heider, Principal Scientist at Donnelly Corporation, Holland, Michigan, conducted ground breaking research in “transient adaptation”, the amount of time vision is decreased due to arc glare reaching the eye during filter switching. They found that high speed surface mode auto darkening filters cause virtually no impairment to vision.

An auto darkening lens will increase productivity by improving the quality of the weld both at the strike point and through the welding run due to clearer vision. Also “head nod” is no longer required reducing stress and strain on the welder and this speeds up the welding process. Eye strain and that “gritty eye” feel no longer occur.

The increase in productivity will pay for the cost of the filter in a few weeks, reduce the possibility of welders “flash” and reduce the risk of cumulative trauma disorder from the “head nod” many welders use to lower the welding helmet. Auto darkening lenses fitted to welding helmets do require a change in technique but the benefits to the welder are worth it.

Recently, Jackson welding helmets and Weldas full Leather welding Jackets were used by welders on the North Queensland Gas Pipeline. The products, provided by ADG Welding Supplies, received favourable reviews from welders on the job. ADG Welding Supplies, is available to showcase pipeline welding safety equipment to interested parties in the industry.