Protective Eyewear Questions
1. Can you comment on fit for people who normally wear glasses - i.e. isn't it necessary to get safety glasses that fit over the regular eyeglasses. I've ruined two different pair of regular glasses because I thought that if I got lenses comprised of 'safety' rated material, e.g. polycarbonate that would work. Well, it might work for safety features, but after a short while I had so many small pieces of metal shavings and welding rod flux imbedded in them, the visibility through them was degraded. To replace these is quite expensive.
2. Why is the tint necessary if the eyewaer has UV protection?
1) Prescription glasses are a problem. Although if the safety lenses protected your eyes from the metal shards and flux yes they did their job. This is a personal fit thing and yes best option is glasses that cover completely your regular glasses.
2) The forge like a cutting torch puts out UV and Infrared. Most glasses are well protected for the UV but very few protect for the infrared spectrum. The chemistry of the additives in the lens can filter out the infrared. Various tints help you see the metal better by filtering out different spectrums of visible light. The didymium ones I use filter out the sodium flare which is the bright yellow light from the forge.
I recommend shade 2 welding lenses such as Uvex Infradura shade 2 (shade 3 which is more common is pretty dark for shopwork as I start to trip over things). You may also find clip ons available that would protect both you and your prescription glasses but you may have to dig a bit for those. I use a pair similar to the above glasses for forge welding and find them much cooler on the eyes Than the rose didymium that are my regular forging glasses. The infradura filters 85% of the infrared and about 99% of the UV
Also www.auralens.net has a more extensive line of specific high temperature lenses. Look for metal working.
I hope this helps.