On Tue, 05 Apr 2005 08:01:22 -0700, in ôõ "Charlie"
wrote:

But isn't nitric acid like, mega dangerous? I thought I'd read that
somewhere. Would you just use it in exactly the same way?

Charlie.

Cencentrated Nitric acid is indeed a highly corrosive material to be handled with care.
But it's not like the bottle will explode in your hands if you jiggle it. It can cause
dangerous burns to skin, and its fumes can be very bad for your lungs and eyes. But
you're not using the concentrated fuming form to etch. Etching silver or other metals
is generally done with a 5 to 10 percent solution of the acid. In that form, it's not
all that different, safety wise, than the correct concentration of ferric nitrate you'd
also be using for the same purpose. The straight acid is a bit more aggressive, and
won't give you quite as clean an etch. And you will need to pay a bit more attention to
good ventillation. When not actually puring concentrated nitric acid from it's bottle,
the bottle stays tightly closed, and needs to be stored somewhere where it will be safe
from falling over and breaking, or access by kids, or the like. And you need decent
ventillation when handling it. Also, and this is critical, NEVER pour water into any
concentrated acid. Instead, pour the acid into water. Small amounts of water in
contact with larger amounts of acid heat up very quickly, and can spatter or almost
explode as it turns to steam, and THAT's dangerous. When the acid is poured slowly into
the water, the heat generated has somewhere to be dissipated (in the greater volume of
water), and you have no problem. Wear an apron, rubber gloves, and eye protection just
to be safe. THAT APPLIES AS WELL, TO HANDLING FERRIC NITRATE. The dry chemical is not
the same danger in terms of splashes and fumes like the concentrated acid is, but it is
still a highly caustic material and can also cause burns to skin, eyes, or lungs if the
dust is inhaled. As with the dilute acid used to etch, in a modest solution, it's not
so dangerous, but again, you still need to be prudent and cautious with ANY acid capable
of etching metals, as it generally will also be able to hurt you i you're careless.
Eyes in particular are at risk, as are your lungs if you have improper ventilation.

The point is that while the concentrated acid does indeed require more care, the salt of
that acid isn't exactly table sugar either. Read up on proper lab techniques for
handling acid for either material. Both can be used safely. But both can be dangerous
if your not properly prepared or take safety just for granted.

Peter Rowe