A crafts forum. CraftBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » CraftBanter forum » Craft related newsgroups » Beads
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Technical questions on etching and annealing



 
 
Thread Tools Display Modes
  #1  
Old June 30th 03, 10:28 PM
Michele Blank
external usenet poster
 
Posts: n/a
Default Technical questions on etching and annealing

another possibility might be that the rougher sides caused more air
pockets/bubbles in the etching medium so didn't etch as completely. when i
etch i always 'work' the acid to alleviate this problem.?? m


"Terry Harper" wrote in message
...
"D Brock" wrote in message
...

1. Is it generally true that opaque glasses etch more easily/evenly

than
transparent glasses?


As opal glasses have a second phase which is crystalline, it can well be
that this is more easily attacked by the etchant than is the body glass.
There are two main types, fluoride and phosphate opals.
--
Terry Harper
http://www.terry.harper.btinternet.co.uk/



Ads
  #2  
Old July 1st 03, 02:31 AM
kitty
external usenet poster
 
Posts: n/a
Default


"Michele Blank" wrote in message
...
another possibility might be that the rougher sides caused more air
pockets/bubbles in the etching medium so didn't etch as completely. when i
etch i always 'work' the acid to alleviate this problem.?? m


"Terry Harper" wrote in message
...
"D Brock" wrote in message
...

1. Is it generally true that opaque glasses etch more easily/evenly

than
transparent glasses?


As opal glasses have a second phase which is crystalline, it can well be
that this is more easily attacked by the etchant than is the body glass.
There are two main types, fluoride and phosphate opals.
--
Terry Harper
http://www.terry.harper.btinternet.co.uk/




That does indeed help. Another thing to watch is the cleanliness of item to
be etched. Make sure there is no grease residue or handling residue [from
hands/fingers] etc...it can act as a 'block' to the etching.

Kitty


  #3  
Old July 1st 03, 05:32 PM
D Brock
external usenet poster
 
Posts: n/a
Default

All:

Thanks for the comments. Just for the record --- yeah, I'm very careful
with this stuff. I actually have (back in university days) used HF acid to
do glass etching (non-artistic), was quite rightly paranoid/careful with the
stuff. It's nasty.

I'm pretty sure that the effects I'm seeing are not related to either the
glass being dirty at start, or to pieces touching each other or the sides of
the container. From the responses I'm getting here and other places, it
seems like my thoughts about different annealing states affecting the
etching properties are at least plausible...

Thanks for the responses --- and other people's thoughts and observations
are still quite welcome! I'm still watching!

--Dave




"Louis Cage" wrote in message
...
Transparent glasses seem to be a bit "stiffer" than opaque ones, so

that
may have something to do with your cracking problem because they would

reach
the "solid" stage quicker than opals. This would trap more heat inside

the
bead and also the outer layer would shrink faster.
Etching creams and liquids are salts of hydrofluoric acid (which in its
pure form is HIGHLY DANGEROUS - I have been told it is just under

Plutonium
on the EPA's "nasty chemicals" list). Since they are salts they are not
very dangerous, but wear gloves and ventilate the area nonetheless.
Hydrofluoric acid etches glass because it dissolves calcium. Probably the
opaque colors have more calcium in them to give them opacity. Soft glass,
such as Moretti, is also known as soda-lime glass. The acid or cream
dissolve the calcium in the lime part of the glass formula. Borosilicate
glass uses Boron instead of soda and lime as a fluxing agent and has no
calcium. That is why you can't etch Pyrex with these creams.
Even if the glass is very clean, you may still get an uneven etch.

More
so with the cream than the liquid. I think (but do not know for sure)

this
is caused by the salts being unevenly dissolved in the carrier solution.

So
stirring the stuff up before you etch the beads may help.
The reason Hydrofluoric acid, and to a lesser extent the salts, is
dangerous is because it will dissolve the calcium in your body (you bones,
teeth, whites of your eyes, etc.). Also if you spill some on you, it
doesn't affect your nerves, so you may not feel it. Also the acid boils

at
room temperature and the vapors are very harmful as well.
SO BE SURE AND WEAR GLOVES AND GOGGLES WHEN YOU WORK WITH THIS STUFF, EVEN
THE CREAM.

--
There are no mistakes, only unexplored techniques

"D Brock" wrote in message
...
Hi ---

I tried out etching some lampwork soft glass (Effetre) beads for the

first
time, noticed some curious things.

Since this was my first go, I used some old beads from my broken beads
jar --- ones that cracked or broke during cooling (in heated

vermiculite)
and were not annealed. I was using Dip 'n' Etch liquid.

I noticed that the opaque beads seemed to etch to a nice matte finish

much
as expected.

However, I noticed that transparent colors etched with more difficulty

(had
to leave in solution longer) and much less evenly. Some surfaces etched
nicely, some etched only in little spots or blotches, and some parts did

not
etch at all. In particular, on one of these transparent beads, was that

the
main surface of the bead (that was probably worked thouroughly in the

flame
and also cooled slowest) etched nicely, but the one finished edge (that
probably did not get worked so thoroughly in the flame) and the other

broken
end (which, being broken, may also be telling me that it was not worked
enough in the flame) hardly etched at all.

Then, looking back into my jar of broken beads, I realized that there

were
a
disproportionate number of transparent beads, few opaque beads.

So, three inter-related questions a
1. Is it generally true that opaque glasses etch more easily/evenly

than
transparent glasses?
2. Is it generally true that opaque glasses are more robust in terms of
resisting cooling shock and/or easily annealing
3. Does the annealing state of glass affect its etching characteristics
(poorly annealed = etch resistant, well annealed = etchable)?

Thanks,

--Dave







 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 05:59 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 CraftBanter.
The comments are property of their posters.