First run with the ribbon burner forge

[EricJergensen]

On 3/10/2016 at 3:01 PM, Blue Duck Forge said:

Can anyone with an understanding of the light spectra produced by a gas forge comment on the safety of using sunglasses around an IR source? I have read elsewhere on this site that sunglasses both don't block IR, and that they actually enable you to open your eyes more and get higher IR exposure, making them doubly dangerous. However, I noticed that noone here appeared to be concerned about the comment above, even though some of the above commenters are demonstrated experts in gas forges. 

Can someone that knows the safe thing to do here please clarify when something like shade 3 or shade 5 glasses is appropriate ppe, and when (if) sunglasses are ever ok around a forge? 

Sunglasses are never okay as PPE. They are not spec'd for impact resistance and they are not spec'd to block IR. Sunglasses are used to deal with glare and other effects from *scattered* sunlight which doesn't really include much IR. However, because they limit your exposer to the visible light that controls iris dilation while *not* limiting the IR, you are likely to let more IR thru to the lens and retina. Cornea damage can occur regardless.

Welding shade #3 or #5 glasses are spec'd to block a certain amount of IR. They are intended for looking directly at incandescent light sources that are quite IR intense. Staring into a coal, charcoal or propane forge requires IR protection because they are such light sources.

The IR damage does appear to have a threshold effect (from the combination of duration and intensity). That is, less than a certain level causes no damage. Probably staring into a campfire is below threshold. Somewhere between there and a forging heat, you need IR protection. I use #3 clip-ons that I flip down for heating and usually flip up for forging.