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Re: units turning red
>A job I did in December of 1994 is now turning
>red when the weather gets cold. There is 600 feet of glass in this sign and
>it is on top of a 12 story building. It will cost thousands of dollars to
>replace this glass
Don,
Ouch!
I live in a warm climate, use only 100% argon and so can't speak for
cold-weather mixes, however, for interior sculpture pieces I used to use a
mix of neon and argon (a rough mix, done at the manifold), without mercury,
to achieve an argon-like purple with about double the brightness of 100% argon.
One of these pieces turned red overnight after 5-6 years of use...I no
longer do this mix.
It sounds like your sign has mercury that's not vaporizing, and that the
carrier gas has done this same switch from purple to red, so instead of
being dim purple when cold it's red when cold. Perhaps some method of
enabling the merc to vaporize (higher mA transformer? Ideas, anyone?) rather
than repumping all the tubes.
-Ted Pirsig