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Use of Hydrofluoric Acid in jewelry shops

#1

Dear Bob Thank you for you assay on HF, It is nice to read a common
sense and experienced article. Hf is very nasty and difficult to
neutralise. For accidents I have some calciumgluconaat. 10% solution
and gel . I do not now the English words for this so here the
formula. Ca ( OOC- CHOH - CHOH - CHOH - CHOH - CH2OH )2 seems to
work on HF acids to neutralise. But I have never have to use it. Do
you know if this stuff can get aged? or can it be used after years?
If not so I need to buy some new.

Greetings Martin Niemeijer Ndesign
Cultuurwerkplaats R10
Rieteweg 10
8041 AK, Zwolle
The Netherlands
info@ndesign.nl
http://www.ndesign.nl
Phone +31 (0)38 7501258
Mobile phone +31 (0)651831576

#2

You might add BAL “British Anti Lewisite” to the list of treatment
materials for HF.

I have only been exposed to minor HF gas leaks but they react with
skin moisture and it STINGS. BAL seems to be a treatment approved
in the UK but not in the US at least back then. Our BAL ointment
came in from the UK in spite of The US FDA. It is best to avoid HF
in any form!

jesse

#3

There has been a lot of discussion regarding the dangers of using
Hydrofluoric acid in the jewellery workshop and it could be that
there is no alternative to this very dangerous acid when working
with titanium. However for enamellers who wish to remove the glass
enamel from the metal base without damaging the metal base, there is
another method originally published in article by Woodrow Carpenter
in Glass-on-Metal vol 16 no 3, August 1997 using molten sodium
hydroxide[anhydrous] which seems to be relatively much safer than
HF.

The method uses standard commercial grade sodium hydroxide [e.g. red
devil lye] heated in a moisture free environment, such as an
thermostatically controlled electric kiln, to 350 degrees
centigrade [650F] for approximately one hour. It certainly works
but as yet I have not found any other enamellers using this process,
they all seem to use HF or just use the piece as scrap metal…

I have discussed this process with a number of chemists who agree
that it is a relatively safe procedure providing you keep all
moisture away from the hot caustic but caution that fumes may be
produced and that the kiln might be damaged in the longer term. The
article published in GOM said that they were not aware of any
vapours [at the specified temperatures] and that no damage appeared
to be caused to the kiln. GOM states that they have been using the
procedure for many years so they should be the best source of
In addition disposal of the waste does not cause a
major environmental problem.

You need to read the full article GOM in detail before trying this
yourself and back issues are available from the GOM website at
relatively low cost . Maybe GOM would make the article free for
publication on the Orchid site in the interests of safety

I make no claim to the safety or effectiveness of this process other
than that stated in the GOM article but I would be interested in
hearing from other enamellers who have had success with this process
or have found any disadvantages/safety issues in its use.

regards
mike kersley [UK]