In article ,
"Gefreiter Krueger" writes:
On Sat, 07 Dec 2013 16:46:18 -0000, Tim Watts wrote:

On Saturday 07 December 2013 16:33 Muddymike wrote in uk.d-i-y:

"Gefreiter Krueger" wrote in message news For a small arc welder for a small job, is a mask really necessary? The
spark doesn't look any brighter than starting at a bright lightbulb.

It is very necessary. You don't need anything fancy though. A simple hand
held shield will do.

Mike

Particularly if you don't want to get a painful case of arc-eye and possible
long term eye damage!

It doesn't look brighter than a lightbulb (this is a small welder), and UV would give me sunburn on my face before it damaged my eyes surely?

You can't see how bright it is - it saturates the recepters.
You can't see the UV components at all.

Different UV wavelengths and intensities have different effects.

Many years ago when gyms might have had high-bay mercury vapour lamps,
one of the hazards was the outer bulb breaking (e.g. hit by a ball or
similar). The lamp seems to carry on working, but somewhat dimmer.

After about half an hour in the gym, typically just as the players
are leaving, they would start to detect stinging in their eyes. The
timing is such that showering was sometimes blamed. Later in the
day/evening, badly bloodshot eyes, and serious stinging. This was
all due to the UV exposure caused by the missing outer glass bulb
in the gym. UV exposure such as this is known to lead to early
onset cateracts, and a contributor to macular degeneration.

The lighting problem required a change to the design of mercury
vapour lamps. The wires inside the outer bulb were changed such
that they burn out on exposure to oxygen, so that a mercury vapour
lamp with a smashed outer bulb (which normally stops the UV) will
quickly burn out and stop the lamp working.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]