Randall Moody on thu 22 apr 99
I have some recipes for underglazes (circa 1952) and am having problems
finding one of the ingredients. The ingredient is calcium sulfide. Is it
known by another name and where can it be found? I have not seen it listed
in any of my suppliers catalogues. Any help would be appreciated. Also, does
anyone have a recipe for a red stain or red underglaze?
Saralyn Lindsey on fri 23 apr 99
Randall,
Although I am new to the pottery world and do it on the weekends, I am
a biochemist during the day, so will only comment on the chemistry part
of your question. Calcium sulfide (Ca++S-2) is a highly toxic
flammable solid that may, when fired in a glaze form calcium sulfate
(Ca++SO--4). Or, it could also form SO2 leaving free Ca++. Don't know,
however, which is taking place or the consequence of the reaction in a
glaze. Perhaps the glaze experts here on clayart will be able to
comment on that, and I will also be interested in their response. I do
know that you can buy calcium sulfide from Aldrich Chemical Co if you
want that ingredient.
Good luck, Sandy Lindsey in Mystic, CT
--- Randall Moody wrote:
> ----------------------------Original
> message----------------------------
> I have some recipes for underglazes (circa 1952)
> and am having problems
> finding one of the ingredients. The ingredient is
> calcium sulfide. Is it
> known by another name and where can it be found? I
> have not seen it listed
> in any of my suppliers catalogues. Any help would be
> appreciated. Also, does
> anyone have a recipe for a red stain or red
> underglaze?
>
_________________________________________________________
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Fay & Ralph Loewenthal on fri 23 apr 99
Randall areyou sure it is not Cadmium Sulphide, which is used
with Selenium to produce reds. The problem with this is that it
is only stable until cone 010 and of course poisonous. Calcium
Sulfate is the constituent of Gypsum (Plaster of Paris). James
Chappell, in his book "The Potter's Complete Book of Clay
and Glazes", gives a recipe for red stain cone 08 to 8. The
recipe is as follows:
Tin Oxide 44.0
Calcium Sulfate 65.0
Silica 21.0
Calcium Fluoride 4.7
Potassium Bichromate 2.0 (Poisonous)
It fires blood red cone 08 to 2, it lightens to pink which each
rise in cone level. There is also a crimson red recipe just
before this one which goes darker from cone 4 to 8. I have
made this crimson red and my wife and customers liked it, but
I could not mill it fine enough.
The ISBN of this book is 0-8230-4202-2, it has a wealth of
info for the potter. Hope this helps Ralph in PE SA.
Louis Katz on sat 24 apr 99
Must be looking for Cadmium Sulfide. Most Poisonous, what do you want to do
this for? It might be safer, smarter, cheaper, and better looking to buy a
commercial glaze (to see it typed from my fingers hurts).
I wouldn't let the Cat in the Hat bring it into my house.
You might look into the Deguassa pigments and I sure the clayart archives
at
http://www.potters.org/ has something on them. I would let the Cat bring
them in, I just wouldn't let him paint them on functional ware and I would
only fire them with excellent ventilation.
Louis
Edouard Bastarache on sat 24 apr 99
------------------
Hello Fay =26 Ralph,
if it is calcium sulfide then the toxicology is as follows
according to =22Dangerous Properties of Industrial Materials=22:
=22A poison via inhalation(...).When heated to decomposition
it emits toxic fumes of SOx=22.
If it is calcium sulfate according to the same source:
=22Toxicity unknown.A nutrient and/or dietary supplement food additive(..).
When heated to decomposition it emits toxic fumes of SOx.
If it is cadmium sulfide then the following text applies:
Cadmium =26 Compounds
Compounds : cadmium oxide=3B cadmium carbonate=3B cadmium chloride=3Bcadmium
sulfate=3B cadmium sulfide.
Uses : The metal is used in electroplating, in solder for aluminium, as a
constituent of easily fusible
alloys, as a deoxidizer in nickel plating, in process engraving, in
cadmium-nickel batteries,
and in reactor control rods.
Cadmium compounds are employed as TV phosphors, as pigments in glazes and
enamels, in
dyeing and printing, and in semi-conductors and rectifiers.
Exposure : Inhalation
Toxicology : Cadmium oxide fume is a severe pulmonary irritant=3B cadmium =
dust
is a less potent irritant
than cadmium fume because it has a larger particle size. Chronic exposure
is associated
with nephrotoxicity. Several inorganic cadmium compounds cause malignant
tumors in
animals.
Inhalation exposure to high levels of cadmium fumes or dust is intensely
irritating to
respiratory tissue. Particle size appears to be a more important
determinant of toxicity
than chemical form. However, most acute intoxications have been caused by
inhalation
of cadmium fume at concentrations that did not provide sufficient warning
symtoms of
irritation. Concentrations of fume responsible for fatalities have been
40 to 50 mg/m3
for 1 hour or 9 mg/m3 for 5 hours. There has been non-fatal cases at lower
concentrations.Pulmonary symptoms and clinical signs reflect lesions ranging
from nasopharyngeal and bronchial irritation to pulmonary edema with also
possibly headache, chills, muscle aches, nausea, vomiting, and diarrhea.
Among survivors , the subsequent course is unpredictable =3B most cases
resolve slowly, but respiratory symptoms may linger for several weeks, and
impairment of pulmonaty function may persists for months.
Long-term inhalation exposure at low levels leads to decreased lung
function and
emphysema.
Chronic exposure to cadmium results in renal damage which may continue to
progress
even after exposure ceases.
Other consequences of cadmium exposure are : anemia, yellow discoloration
of the teeth,
rhinitis, occasional ulceration of the nasal septum, damage to the
olfactory nerve, and
anosmia.
Chronic exposure to high levels of cadmium in food has caused bone
disorders, including
osteoporosis and osteamalacia. Long term ingestion, by a Japanese
population, of water
and food contaminated with cadmium, was associated with a crippling
condition,
=AB itai-itai =BB disease.The affliction is characterized by pain in the =
back
and
joints, osteomalacia, bone fractures, and occasional renal failure, and
most often affects
women with multiple risk factors such as multiparity and poor nutrition.
Occupational exposure to cadmium has been implicated in a significant
increase of lung
cancer. The IARC has determined that there is sufficient evidence in
humans for the
carcinogenicity of cadmium and cadmium compounds. It also appears that
cadmium has
the capability to alter genetic materials, particularly chromosomes.
The 1995 ACGIH threshod limit value-time-weighted average (TLV-TWA) for
elemental
cadmium and compounds as Cd is 0.01 mg/m3 for total particulate dust or
0.002 mg/m3 for the respirable fraction of dust (while it is 10mg/m3 for
titanium dioxide for total particulate dust in Quebec)=3B there is an A 2
suspected human carcinogen designation for both forms.
The urinary excretion of cadmium itself bears no known relationship to the
severity or
duration of exposure and is only the confirmation of absorption.Absorbed
cadmium is
retained in the body to a large extent, and excretion is very slow.
The important thing is your level of exposure to cadmium, it may vary if
you are a pottery
factory worker, a teacher, a full-time studio potter or a part-time.It
certainly
depends also on the amount used over a given period of time .In the wet
state, these compounds are certainly much less hazardous than as dust
route of entry being inhalation).Factories can afford the monitoring of
cadmium exposure but it is not the same for artists and craftpersons.
So good house keeping of your studio is important.Avoidance of processes
generating unnecessary dust is also important, and the wearing of an
approved dust mask when the exposure seems hazardous is mandatory.
Reference :Chemical Hazards of the Workplace, Proctor =26 Hughes, Fourth
Edition.
Edouard Bastarache
In =22La Belle Province=22
edouardb=40sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/=7Eedouardb/
-----Message d'origine-----
De : Fay =26 Ralph Loewenthal =3Cfayralph=40intekom.co.za=3E
=C0 : CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
Date : 23 avril, 1999 15:35
Objet : Calcium Sulphide
----------------------------Original message----------------------------
Randall areyou sure it is not Cadmium Sulphide, which is used
with Selenium to produce reds. The problem with this is that it
is only stable until cone 010 and of course poisonous. Calcium
Sulfate is the constituent of Gypsum (Plaster of Paris). James
Chappell, in his book =22The Potter's Complete Book of Clay
and Glazes=22, gives a recipe for red stain cone 08 to 8. The
recipe is as follows:
Tin Oxide 44.0
Calcium Sulfate 65.0
Silica 21.0
Calcium Fluoride 4.7
Potassium Bichromate 2.0 (Poisonous)
It fires blood red cone 08 to 2, it lightens to pink which each
rise in cone level. There is also a crimson red recipe just
before this one which goes darker from cone 4 to 8. I have
made this crimson red and my wife and customers liked it, but
I could not mill it fine enough.
The ISBN of this book is 0-8230-4202-2, it has a wealth of
info for the potter. Hope this helps Ralph in PE SA.
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