From: REMOVE_THISdwilkins@means.net (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Etching a line in Glass or Plexi-glass.
Date: Mon, 21 Sep 1998 22:08:51 GMT

On Tue, 15 Sep 1998 08:33:29 -0700, Roger Haar
<haar@physics.arizona.edu> wrote:

>HI,
>        You can buy an glass etching paste in small quantities at most craft
>stores.
>(My wife did some etched calligraphy this way)  Just mask off the section
>around the line using masking tape (as I recall) and remember to push the tape
>in very well.

My wife owns an arts and crafts store and sells this stuff. You can
buy a waxy like sheet and apply it to glass. This leaves an exposed
pattern which creates the area to be etched with a proprietary
"non-acidic, non-hazzardous cream". (the waxy stuff masks the area not
etched)

The "non-acidic, non- hazardous" cream is an ammonium bifluoride
solution which is hardly "non-acidic or non-hazzardous" along with
some thickener (probably a starch) to prevent running.

As a retired chemist I know that you can get some nasty fluoride burns
from ammonium bifluoride. An aqueous solution will have a pH of ~2
which of course is acidic. I "innocently" requested a MSDS sheet from
the vendor and it avoids providing any useful information. For the
non-chemists an ammonium bifluoride solution is what you would get if
started with a solution of hydrofluoric acid and added enough ammonium
hydroxide to neutralize one half of the acid present.

The etchant from a craft store will etch the glass and you can use a
lot of different materials to mask the area you don't want etched but
do be careful about leaving the cream in contact with the skin and do
wear appropriate eye protection.

Mechanical abrasion is probably the best method to mark a permanent
line on Plexi. The line can be enhanced by smearing on a paste and
then wiping it off with a cloth. Enough material should remain in the
"groove" to make it more visible. We did this using zinc oxide to
improve the visibility of markings on burettes. The process had to be
repeated as the zinc oxide was not permanent.