I do not know anyone who uses dark glasses when soldering with oxy
and propane. When using oxy acetylene, the flame is bright enough
to leave serious spots in your (my) vision even if not looking
directly at it. This is just not the case with propane, for
American Welding Society and OSHA both require shade 3-5 for brazing
(our soldering) there is no differentiation for fuel type as they
all emit light that can damage your eyes when brazing.
Three sources for eye strain/damage from light radiated by torches,
the work and the brazing surface.
Infra Red, ie heat probably the biggest danger in brazing cooks the
Visible light, more a cause of eye strain than damage at lower
levels but can damage if bright enough with long enough exposure
think platinum soldering.
UV, not a big amount of UV from brazing operations and most plastic
lenses (safety glasses) are pretty good at stopping it.
Aur92 and Didymium lenses are glass lenses that are visible light
filters, they don’t much of anything about UV or Infra Red. They are
specifically designed to knock down the yellow sodium flare in hot
glass working and do a good job on the yellow flare from flux and
If you solder all day every day you need to wear some form of shaded
lens (not didymium or Aur92) to knock down the infra red.If you are
soldering platinum then you need to where at least a shade 5.
James Binnion Metal Arts