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Re: mercury

> I think all of us are concerned, I go and have my blood checked periodically
> for mercury. What can be done about blowing on hot leaded glass? Should we
> all switch to another type of glass?

John & Howie,

I went thru a phase were I was absolutely panicked about mercury.  At a
shop I worked at, I carried a charcoal trap that I put in line with my
blowhose.  I refused to even seal a new bottle on the manifold without
that trap. The bombing table there was like a toxic waste dump.  If you
looked really close, there were minute droplets of Hg in EVERY crack and
crevice.  The other benders called me "Mr. Paranoid."

I've relaxed a bit, as now I have my own shop and I treat mercury very 
respectfully.  I did an extensive amount of personal research into Hg 
contamination, and I have concluded the following:

    1.  Spills should be cleaned up immediately, before they disperse 
into every smaller and smaller droplets.  A small suction device is good, 
as is masking tape (yes, I got this out of Fusion magazine and it seems 
to work great).
    2.  The practice of sprinkling sulfur on Hg is only moderately 
effective.  It does form a "skin" of HgS over the droplet, but does not 
completely amalgamate it.  Finely powered zinc works better.  I have some 
that is "60 mesh" size (whatever that is) and it reacts more vigorously 
and completly than sulphur.  You can actually sweep these "rocks" up.  
Some commercial Hg clean-up products contain sulphur mixed with strong 
alkalines like lye.  This is supposed to be effective, but it's perhaps 
only practical in a large-scale decontamination.
    3.  Once you fail to take step #1, the decontamination process 
becomes many fold more difficult - perhaps impossible without discarding 
of contaminated surfaces.

I also believe a great way to control spills is to have your bombing table
of a smooth surface, like Formica, and do all your filling on that table. 
A shallow "ditch" routed around the perimeter of the table will catch any
droplets that roll.

This all applies to spills of course.  The other sources of contamination 
would be re-using mercury traps, exhaust from your mechanical pump, and 
repairing mercury tubes.  All of these are avoidable.  The pump exhaust 
can (should) exit to the outside.

I agree with Tom (he mentions in the SB article on him) that most people 
use way too much Hg in tubes.  I have seen tubes with a giant pea-sized 
glob rolling around.  All that's needed is enough to vaporize to an 
equillibrium with the filling pressure of the tube.  This is usually just 
a few "salt" grains.  It takes a bit longer to age in the tube, but once 
it does it lights just as well even in cold weather.

I feel comfortable because I know I'm doing everything I can to protect 
my health, and I know many older neon folks that were much more careless 
during their carrers. Most of them are okay.  I know that's a lousy 
gauge of effectiveness, but it makes me feel better! 

As to lead glass - I have wondered about that too, but I have never heard 
evidence that any lead is volatilized during the heating process.

     -John Anderson
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