Building own telescope - ground glass making

wrote in message
oups.com...
I wouldn't recommend hydroflouric acid. I read somewhere that it pases
through the skin and finds it way to the bones. Do we have any chemists
or doctors aboard who can confirm this please? Getting hold of the
stuff probably wouldn't be easy for the layman ayway.

Chris.B


Hydrofluoric Acid does penetrate deeply in dilute form so the effects are
delayed. See http://www.emedicine.com/emerg/topic804.htm for more details.

This stuff is extremely hazardous and must only be used if there is no
other alternative. The COSHH regulations 2002 apply to this substance.

Alan

In message , Steve Taylor
writes
wrote:
I wouldn't recommend hydroflouric acid. I read somewhere that it pases
through the skin and finds it way to the bones. Do we have any chemists
or doctors aboard who can confirm this please? Getting hold of the
stuff probably wouldn't be easy for the layman ayway.

Its very very nasty stuff. Look up "HF poisoning" in Google.

We use a special paint remover at work which contains HF. We also have
the specialist emergency kit that has to accompany it. If ANY HF is
dropped on the skin, it has to be flushed and a gel containing Calcium
fluconate rubbed in, and rubbed in, and rubbed in. The fluconate
sequesters the fluorine and the resulting compound is (relatively) inert

Very minor nitpick, but that's gluconate. ISTR that hydrofluoric acid
can penetrate pinholes in gloves, but I've never had occasion to use it
(thankfully).
--
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Remove spam and invalid from address to reply.

Alan Gardiner wrote:
wrote in message
oups.com...

I wouldn't recommend hydroflouric acid. I read somewhere that it pases
through the skin and finds it way to the bones. Do we have any chemists
or doctors aboard who can confirm this please? Getting hold of the
stuff probably wouldn't be easy for the layman ayway.

Chris.B

Hydrofluoric Acid does penetrate deeply in dilute form so the effects are
delayed. See http://www.emedicine.com/emerg/topic804.htm for more details.

This stuff is extremely hazardous and must only be used if there is no
other alternative. The COSHH regulations 2002 apply to this substance.

There is no warning at all with HF. You only feel the excruciating pain
and damage much later. Even experienced chemists are *extremely* careful
with it and no-one will touch it these days without having the (partial)
antidote of calcium gluconate cream to hand. The gruesome safety film
for HF handling itself usually causes casualties when it is shown to
audiences of tough steel welders and geologists. Read the MSDS very
carefully this stuff is vicious!

Scarily I found 10L of 30% HF in my Belgian greenhouse in a plastic
container brittle with age. When I picked it up I thought it was pink
paraffin. I put it down very very gingerly. It is (or rather was) sold
there as glass cleaner for commercial scale grape glasshouses.

I doubt very much that ordinary members of the public can buy it.

You might be able to take a piece of glass along to a specialist glass
worker who knows how to use HF etching to acheive the finish you want.
But it would probably be cheaper to buy some ground glass off the shelf.

Sand blasting with fine sand is the other physical alternative depending
on how flat you need it to be.

Regards,
Martin Brown

I have heard a story about an electrician whom had to have his arm removed
after touching the stuff.
--
Wishing you clear dark skies
Jim Vincent.
jims astro pages www.jimsastro.com
Castle Point Astronomy Club www.cpac.org.uk


wrote in message
oups.com...
I wouldn't recommend hydroflouric acid. I read somewhere that it pases
through the skin and finds it way to the bones. Do we have any chemists
or doctors aboard who can confirm this please? Getting hold of the
stuff probably wouldn't be easy for the layman ayway.

Chris.B