On Safety Eyewear...

Rose Didymium Safety Glass

TECHNICAL DATA

" Rose didymium is a high luminous transmittance filter specifically designed to absorb bright yellow sodium flare (589 nm) which occurs when heating glass. Didymium lenses protect the eyes from certain visible and UV light produced in the glassblowing process. They enable the glassblower to see the glass while it is being worked in the flame.

This is the classic filter that has been used for many years in all types of hot glass applications, as well as kiln working. The lens is dichromic (exhibits different colors under various light sources). Under incandescent light, the lens is a pronounced rose color, but changes to greenish blue under fluorescent light.

The spectral analysis of this glass at 3.2 mm thick indicates that it has good protection against ultraviolet radiation up to 360 nm, has excellent filtration at the sodium line, and excellent overall visible transmission from 400 nm to 725 nm. The glass does not offer much protection in the near or mid infrared ranges.

In general, this lens is adequate for many glass-working applications where the amount of radiation generated is low.

Suggested uses:
Beginning lamp-work using hot head torches and MAPP gas, or propane torches with soft glass. Periodically viewing small kilns, acetylene torch work on solver and gold jewelry, enameling of jewelry, and operation requiring occasional viewing of heat sources in excess of 1000 degrees, but not for use with high pressure torches on hard materials where very high temperatures are generated. "

from the East Carolina University Glassblowing Services technical web site, information listed as ' Information provided courtesy of: Phillips Safety Products '

I have been using these to protect my eyes in the forge for years (almost 20 at this point). I highly recommend them for anyone considering a long working life in the forge. My standard is - If you look at something and its bright enough to make you see spots when you look away GET A PROTECTIVE LENS. Those I have seen (too often!) who do things like use oxy torches or forge weld without protective lenses are just plain foolish. A blind man cannot be a blacksmith.

Centaur Forge lists them - but seems to be always out of stock. Also the most expensive.

I checked with a number of glass blowing suppliers

http://www.jodelglass.com/shopsite_sc/store/html/page26.html

has the best selection of types. Ships orders to Canada, uses Paypal

http://www.glassmart.com/didymium.asp

is the best price. Ships to Canada - but only via credit card. I ordered from them myself about a month ago. Their sales guys have been extremely fast on any questions. The package arrived quickly and in good order.