Michelle  Pretorius



Michelle @ vitrics.co.za



082 56 000 69




Didymium and didymium-variant filters (like the next-generation AUR-92) are sodium flare (yellow) filters. They will remove the yellow in the flame, they will remove the yellow flare that results when the flame hits metals or glass. It is not a protective filter, but a filter that allows you to see your work better. Didymium and the variants do not filter IR to any great extent. Please don't confuse them with specific design lenses for filtering IR. Kiln and furnace workers are exposed to much greater amounts of IR than torch workers (unless you are working 2-3" in diameter or larger).

Damage to the eye from IR sources is cumulative. And it affects people differently. There is some data that shows that people with high content of melanin (skin colorant) have a higher resistance to IR damage, meaning that it will take longer for them to show the

signs of IR injury than those that have lesser amounts of melanin.  For example, people of equatorial descent (lumping together a lot of racial backgrounds, I know) like Mediterranean , African, Indian, etc. typically have darker skin colors, and brown eyes. These people tend to have less IR related eye injuries than a person of northern

European descent with fair skin and blue eyes. The classic case is the glassblowers of Murano , Italy . For hundreds of years these people have been blowing glass in front of furnaces and glory holes with little historical evidence of eye damage. Compare that to the

glassblowers of old England , where there was a high level of eye damage, in fact this is where the term "glassblowers cataract" originated (1700's).  

The eye does not have pain receptors for burns. The only indication you have of over exposure to IR is dry itchy eyes, as the eye reacts to the desiccation from the heat. In long term exposures, this will lead to the development of retinal burns and corneal irritations which lead to cataracts.  

What does this mean to you? If your work is small soldering or doing granulation, then didymium will help you see your work better. You don't have a massive IR exposure, but you should be aware of the symptoms and take the necessary measures to protect yourself if your work changes. If you are doing casting or enameling with a kiln or furnace, or large, heat intensive work, then you need specific IR filters.

 It is a common misunderstanding that sunglasses are good to wear while working in front of a kiln or torch, after all, sunlight is hot, right? Sunglasses are about the worst thing you can wear, in fact. Sunglasses typically do not filter IR. UV, yes, but UV is not an issue for the work you are doing. Sunglasses pass IR, and with your pupil wide open because you are working inside and the lenses are so dark, your eye is getting blasted with IR.  

I've read that a lot of metal workers have tried using welding filters from the welding shop, but have found them to be too dark. A welding supply shop is going to stock the items that welders need,not necessarily the items that jewelers need. We have found that a shade 2.0 filters 98% or better of the IR, while still allowing 40% visible light. Compare this to a shade 5 (the usually available filter) which filters 99% of IR and allows only 5% visible light.