Ditmar on mon 21 feb 05
----- Original Message -----
From: "Steve Slatin"
To:
Sent: Monday, February 21, 2005 1:55 PM
Subject: Re: Explain Copper and silver sulphides
>
> Silver sulphide is Ag2S, two atoms of silver for each
> sulpher. It's the black corrosion that develops on
> metal silver when exposed to sulpher, such as in an
> egg (ever eaten an egg with a silver spoon? Yuck!).
> It's *very* insoluble in water, and pyrophoric.
>
>
Pyrophoric....no ! Even finely powdered silver isn't.
The oxides of both are easier to find and cheaper. You might want to try the
formulas with those to see if they work.
The sulfides would most easily be prepared using hydrogen sulfide
gas....very toxic in the wrong hands / environment. I don't recommend it.
Silver chloride is another possibility. Just precipitate it from a silver
nitrate solution with sodium chloride ( salt). ....Copper chloride..a pain
in the ass. It absorbs water from the atmosphere and "melts".
Copper oxide is readily available from ceramics suppliers.
Silver oxide can be made from the nitrate. Dissolve it, precipitate with a
hydroxide (sodium), and then heat to form the oxide itself, ..filter, wash
and dry.
If you aren't comfortable with the chemicals, I definitely wouldn't make my
own. It's easier and less BS to buy them. ....False economy.
Ditmar
Fredrick Paget on mon 21 feb 05
>I am interested in a series of glaze formulas in the Complete Potter
>Lustres by Margery Clinton. What are copper and Silver Sulphides? or
>can they be easily made in the studio?
>Llewellyn
>
They can be made and I did make some a few years ago when I was
fooling with lustre glazes,.
It goes like this:
You can react cold sodium polysulfide solution with a solution of a
salt of copper or silver and filter out the sulfide precipitate and
wash it and dry it. Wash it many times with water while it is still
in the funnel. I used a Melita coffee filter . Both sulfides are
black and nearly insoluble in cold water. Salts you could use are
copper sulfate and silver nitrate. Silver nitrate is caustic and if
you get it on you you turn black.
Don't ask me for a recipe. It can be figured out but since the
product is insoluble an excess of one thing or the other can be
washed out.
You make the sodium polysulfide by reacting a hot solution of sodium
Hydroxide with powdered sulfur and long stirring while it is near
boiling hot. I used a lab magnetic stirrer/hotplate . Keep adding
sulfur until no more reacts and filter out the excess.
Sodium hydroxide is lye and dangerous in untrained hands. It is
exothermic when mixed with water so only dissolve it in cold water
and use care to avoid splashing or adding it too fast so it boils
over. It reacts with aluminum. Use a Pyrex glass Erlenmeyer flask and
glass or plastic funnel.
If you try this there are dangers such as burns and poisoning from
chemicals and you should have had training in lab work to attempt it.
Wear gloves and eye protection. Don't try to make a lot all at once.
Considering all the difficulties , why not try to buy the sulfides
from a dealer? Try Bryant labs, Berkeley CA.
--
From Fred Paget, Marin County, California, USA
fredrick@well.com
Charter Member Potters Council
Llewellyn Kouba on mon 21 feb 05
I am interested in a series of glaze formulas in the Complete Potter
Lustres by Margery Clinton. What are copper and Silver Sulphides? or
can they be easily made in the studio?
Llewellyn
Steve Slatin on mon 21 feb 05
Llewellyn --
The sulphides as a group are minerals that contain (1)
sulpher (2) an electropositive element, and (3) no
oxygen.
Galena is one of the best known suplhides, it's lead
and sulpher (PbS), one atom of each in a molecule.
Silver sulphide is Ag2S, two atoms of silver for each
sulpher. It's the black corrosion that develops on
metal silver when exposed to sulpher, such as in an
egg (ever eaten an egg with a silver spoon? Yuck!).
It's *very* insoluble in water, and pyrophoric.
Copper sulphide is more complex; it exists in
different states including Cu2S and CuS2 (Copper
Pyrite, created only under high pressure). All I
remember about this is it's an irritant to eyes,
mucous membranes, and exposed skin -- but I have no
recollection of what is necessary for safe handling.
Best wishes -- Steve Slatin
--- Llewellyn Kouba
wrote:
> I am interested in a series of glaze formulas in the
> Complete Potter
> Lustres by Margery Clinton. What are copper and
> Silver Sulphides? or
> can they be easily made in the studio?
> Llewellyn
=====
Steve Slatin -- Don't Ever Antagonize The Horn
__________________________________
Do you Yahoo!?
Meet the all-new My Yahoo! - Try it today!
http://my.yahoo.com
Steve Slatin on tue 22 feb 05
Ditmar --
You are right, silver metal is not pyrophoric. And
the oxides are easier and cheaper. But if you are
looking for sulphide activity, you need the sulphide
-- it does what it does because it's got sulpher and
no oxygen. And the sulphides are often pyrophoric --
I searched "pyrophoric" and "sulphide" and got the
following site --
http://people.clarkson.edu/orgs/indhygie/manual/chemhyg.htm
which lists over 20 pyrophoric sulphides.
I agree entirely with your position that it's a false
economy to make your own chemicals. To this I'd add
that it's also dangerous.
Regards -- Steve Slatin
--- Ditmar wrote:
>
> Pyrophoric....no ! Even finely powdered
> silver isn't.
>
> The oxides of both are easier to find and cheaper.
=====
Steve Slatin -- Don't Ever Antagonize The Horn
__________________________________
Do you Yahoo!?
The all-new My Yahoo! - Get yours free!
http://my.yahoo.com
Llewellyn Kouba on tue 22 feb 05
Fred,
I definately am not up to being a lab technician with my untrained
hands. I would purchase something readily available on the market
through chemical manufacturer or Clay suppliers etc. I could go the
route with ready made glazes with lustre as well but would like to do
some experimentation with clay- pastes but all this only where I am in a
safe-zone with handling and firing.
Llewellyn
Fredrick Paget wrote:
>> I am interested in a series of glaze formulas in the Complete Potter
>> Lustres by Margery Clinton. What are copper and Silver Sulphides? or
>> can they be easily made in the studio?
>> Llewellyn
>>
>
> They can be made and I did make some a few years ago when I was
> fooling with lustre glazes,.
> It goes like this:
>
> You can react cold sodium polysulfide solution with a solution of a
> salt of copper or silver and filter out the sulfide precipitate and
> wash it and dry it. Wash it many times with water while it is still
> in the funnel. I used a Melita coffee filter . Both sulfides are
> black and nearly insoluble in cold water. Salts you could use are
> copper sulfate and silver nitrate. Silver nitrate is caustic and if
> you get it on you you turn black.
>
> Don't ask me for a recipe. It can be figured out but since the
> product is insoluble an excess of one thing or the other can be
> washed out.
>
> You make the sodium polysulfide by reacting a hot solution of sodium
> Hydroxide with powdered sulfur and long stirring while it is near
> boiling hot. I used a lab magnetic stirrer/hotplate . Keep adding
> sulfur until no more reacts and filter out the excess.
>
> Sodium hydroxide is lye and dangerous in untrained hands. It is
> exothermic when mixed with water so only dissolve it in cold water
> and use care to avoid splashing or adding it too fast so it boils
> over. It reacts with aluminum. Use a Pyrex glass Erlenmeyer flask and
> glass or plastic funnel.
>
> If you try this there are dangers such as burns and poisoning from
> chemicals and you should have had training in lab work to attempt it.
> Wear gloves and eye protection. Don't try to make a lot all at once.
> Considering all the difficulties , why not try to buy the sulfides
> from a dealer? Try Bryant labs, Berkeley CA.
> --
> From Fred Paget, Marin County, California, USA
> fredrick@well.com
> Charter Member Potters Council
>
> ______________________________________________________________________________
>
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
--
http://www.assumptionabbey.com/Pottery/index.html
Llewellyn Kouba
ABBEY POTTERY
Stoneware, Porcelain, Terra Cotta, and
Native Clays.
Assumption Abbey, Richardton ND USA
Lee Love on wed 23 feb 05
A mentor of mine back home once said, during a visit to
Mashiko, "Beware of people who speak with great authority about
something they know nothing about."
Using soluble colorants isn't about cost, but about
achieving effects that you cannot achieve with other oxides. For
an example, please go look at Gary Holts "soluble salts" work. Gary
has been very helpful with information about the technique:
http://www.garyholt.com/
You buy the chemicals at chemical supply stores (Thanks Gary!):
Alfa Aesar - www.alfa.com
Spectrum Chemicals - www.spectrumchemical.com
Bryant Laboratory - www.bryantlaboratory.com
Gary also recommends this book: Arne Ase's book, Water color on Porcelain', Norwegian University Press, 1989
There is an article here (not sure how useful it is. I can't tell who the author is):
http://www.ceramicstoday.com/articles/081098.htm
Yes, you have to be careful with water soluble oxides, so it isn't for doofuses. ;-)
--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ WEB LOG
http://claycraft.blogspot.com/ Photos!
| |
|
