About these funny kinds of glasses:
“Didymium” glasses are made with glass which is colored by a
combination of neodymium and praseodymium, which are rare earth
elements. Together in glass they partially filter the wavelength
which sodium gives off when molten (the yellow orange), and which
is very damaging to the eyes. Since sodium is a major component
of glass, this is why glassworkers use them.
Glassworkers who do furnace work, where they are staring at the
stuff at very high temperatures for very long periods of time, or
who work in borosilicate which melts at a much higher temp than
regular glass, usually add extra filters/darkening lenses/gold
coatings, etc. to their glasses. Also, some glassworkers work in
quartz, which is pure silica, and which melts at even higher
temps (and often using hydrogen torches). The hotter you go, the
more eye protection that’s required.
The Aur-92’s you’ve seen mentioned here are made by Aura Lens
Products. Theses are not didymiums but use a laminate of some
kind which filters much more harmful stuff than do the didymiums.
Most torch glassworkers I know have switched to them becuase
they’re so superior to didymiums, gold coated or not. They’re not
cheap, however. Aura Lens offers several lenses for a number of
different heat applications, including (I think) lenses which
are gold coated. These of course, are even more expensive. These
often have better absortion in the infrared and UV. You can ask
for a spectral analysis from Aura Lens, or access this info from
If you are working glass in a torch, didymiums are fine, but you
will find much less eye fatigue with the Aur-92’s. Unless you are
working borosilicate, and for hours at a time, you don’t need to
spend the extra money on any other coatings.
If you are a jeweler and are doing primarily gold and silver
soldering, the Aur-92’s will probably be more than adequate. The
temperature of most soft glass torch work is about 2000 degrees,
so you’re still way under that at solder temperatures, or even
occasional casting. If you do platinum work, or a lot of casting
then you might consider investigating a different lens coating
that will give you more protection at these higher temperatures.
The best way to do this is call the manufacturer. This is a very
user-friendly small company, and the tech person you will likely
talk to is the one who helped invent the glasses.
I stare at the torchflame doing glasswork for sometimes hours at
a stretch, and experience very little eye fatigue with the
Aur-92’s. The great thing about these lenses is that they aren’t
dark! You can still see everything about your work, and all the
annoying bright yellow-orange flare is gone.