I found these in my shop clean up made by Thermacote Co. called Thermo cobalt blue Shade LT welder filter lens. Anyone herd of this type of lens fits a old school welding helmet 2x4. Not sure when or how I came about getting it. It seems I read at one time that they were used for gas welding aluminum. thanks
While I have never used one, I understand that the cobalt blue lenses were used mostly for torch welding and brazing to filter out the bright yellow flare caused by sodium in some of the fluxes used for those operations. You are correct that these are used for gas welding aluminum, again due to the flare from the flux. The "sodium flare" is really bright and can make it very difficult to see your actual weld. I think I have read that they were also used by foundry workers for the same reason.
I know a few people who do hot glass work, and they use blue lenses as well due to the sodium flare that happens when fusing glass with a torch.
It looks like you can still buy lenses similar to what you have here:
https://www.forneyind.com/products/safe ... e--shade-6
I know a few people who do hot glass work, and they use blue lenses as well due to the sodium flare that happens when fusing glass with a torch.
It looks like you can still buy lenses similar to what you have here:
https://www.forneyind.com/products/safe ... e--shade-6