Re: ATM ACID ETCHING OF GLASS

[Dominic-Luc Webb molmed <Dominic.Luc-Webb@molmed.ki.se>]

On Fri, 17 Aug 2001, John D. Upton wrote:

>
> Kurt,
>
> At 10:22 AM 8/17/01 -0400, you wrote:
> >I am curious to try a glass etching experiment using hydroflouric acid.  Yes
> >I know the dangers and risks.  My experiment would use a very (?) dilute
> >solution, 99.5% water and only 0.5% HF.  I am wondering if there are any
> >chemists out there with any opinions as to how dangerous HF is diluted to
> >this level, I am well aware of the dangers at higher concentrations.  Thank


I do molecular medicine, not quite the right person, but I
dabble in this subject from time to time...

Basically, 1:200 is not anywhere near as big as a problem,
but this is still relatively strong acid. The closest
halide acid I work with is HCl and this dilution would
not cause any particular problem, especially if some
rinsing water is available. 0.5% HF would equate to
something close to 1 M HCl, which you might not even feel
if applied directly to the skin.

But the danger does not end there... HF is known to cause
injury which is neither visible nor painful for many
hours after the incident of application to the skin.
Further, while trace (keyword, "TRACE") amounts of F are
needed for nutritional reasons, it takes very little more
than the USRDA to cause serious toxicity and death.
Because HF is a fuming acid, I would be very cautious
to not inhale any of the fumes. I know of no deaths
resulting from exposure to HF fumes in a non-industrial
application, but there's no pride in being first here.
LC50(1 hour) is 1780 ppm by inhalation in monkeys.


Cheers,


Dominic