John Britt on sat 10 dec 05
Edouard B. has a new article on Ceramics Today about Potassium dichromate:
http://www.ceramicstoday.com/
Best,
John Britt
www.johnbrittpottery.com
annapoorna sitaram on sat 10 dec 05
hi
any glazes with potassium di chromate or potassium chromate.
thank you
annapoorna
Ron Roy on sat 10 dec 05
Hi Annapoorna,
Just so you know - Chromates are potent animal carcinogens - strontium
chromate being the strongest.
RR
>hi
>any glazes with potassium di chromate or potassium chromate.
>thank you
>annapoorna
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
John Hesselberth on sat 10 dec 05
On Dec 10, 2005, at 12:38 AM, annapoorna sitaram wrote:
> hi
> any glazes with potassium di chromate or potassium chromate.
> thank you
> annapoorna
Hi Annapoorna,
I don't have any glaze recipes to offer, but I hope you know that
potassium dichromate and potassium chromate are classified as known
human carcinogens and potassium dichromate is also a powerful
oxidizer. They are not something that you want to handle unless you
really know what you are doing and have the equipment to handle them
safely.
If you want to learn more about this you can download a section of
the 11th Report on Carcinogens from the National Institute of Health
web site at
http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s045chro.pdf
Before other Clayarters get concerned, potassium dichromate and
potassium chromate have the chromium in the +6 valence state and that
is the what results in them being classified as a carcinogens. The
chromium oxide which we use (Cr2O3) has chromium in the +3 valence
state and that is not the same kind of problem.
Regards,
John
Edouard Bastarache Inc. on sat 10 dec 05
POTASSIUM DICHROMATE
IDENTIFICATION :
CAS No. : 7778-50-9
Chemical formula : K2Cr2O7
Molecular weight : 294.18
MAIN SYNONYMS :
French names :
Bichromate de potassium
Dichromate de potassium
English names :
Dichromic acid
Dipotassium salt
Potassium bichromate
Dipotassium dichromate
USES AND SOURCES OF EMISSION :
Manufacture of paints, inks and in ceramics.
HYGIENE AND SAFETY :
I. Physical and Chemical Properties :
Appearance : Orange-red crystals or powder
Odor : Odorless.
Solubility : 6.5% @ 10C (50F) in water.
Specific gravity : 2.676 @ 25C/4C
pH : 4.04 (1% aq. solution) 3.57 (10% aq. solution)
% Volatiles by volume @ 21C (70F) : 0
Boiling point : 500C (932F)
Melting point : 398C (748F)
II. Fire Fighting Measures :
A. Fire :
Not combustible, but substance is a strong oxidizer and its heat of reaction
with reducing agents or combustibles may cause ignition. Releases oxygen,
upon decomposition, which enhances combustion.
B. Explosion :
Contact with oxidizable substances may cause extremely violent combustion.
C. Fire extinguishing media :
Flood with large amounts of water. Water spray may be used to keep fire
exposed containers cool. Do not allow water runoff to enter sewers or
waterways.
D. Special information :
In the event of a fire, wear full protective clothing and NIOSH-approved
self-contained breathing apparatus with full facepiece operated in the
pressure demand or other positive pressure mode.
PREVENTION :
I. Stability and Reactivity :
A. Stability :
Stable under ordinary conditions of use and storage.
B. Hazardous decomposition products :
Burning may produce chrome oxides.
C. Hazardous polymerization :
Will not occur.
D. Incompatibilities :
Reducing agents, acetone plus sulfuric acid, boron plus silicon, ethylene
glycol, iron, hydrazine, and hydroxylamine. Any combustible, organic or
other readily oxidizable material (paper, wood, sulfur, aluminum or
plastics).
E. Conditions to avoid :
Heat, incompatibles.
II. Handling and Storage :
Protect against physical damage. Store in a dry location separate from
combustible, organic or other readily oxidizable materials. Avoid storage on
wood floors. Remove and dispose of any spilled dichromates; do not return to
original containers. Wear special protective equipment for maintenance
break-in or where exposures may exceed established exposure levels. Wash
hands, face, forearms and neck when exiting restricted areas. Shower,
dispose of outer clothing, change to clean garments at the end of the day.
Avoid cross-contamination of street clothes. Wash hands before eating and do
not eat, drink, or smoke in workplace. Containers of this material may be
hazardous when empty since they retain product residues (dust, solids);
observe all warnings and precautions listed for the product.
III. Accidental Release Measures :
Ventilate area of leak or spill. Wear appropriate personal protective
equipment.
Spills : Sweep up and containerize for reclamation or disposal. Vacuuming or
wet sweeping may be used to avoid dust dispersal.
IV. Exposure Controls/Personal Protection :
A. Ventilation System :
A system of local and/or general exhaust is recommended to keep employee
exposures below the Airborne Exposure Limits. Local exhaust ventilation is
generally preferred because it can control the emissions of the contaminant
at its source, preventing dispersion of it into the general work area.
If the exposure limit is exceeded and engineering controls are not feasible,
a half facepiece particulate respirator (NIOSH type N95 or better filters)
may be worn for up to ten times the exposure limit or the maximum use
concentration specified by the appropriate regulatory agency or respirator
supplier, whichever is lowest. A full-face piece particulate respirator
(NIOSH type N100 filters) may be worn up to 50 times the exposure limit, or
the maximum use concentration specified by the appropriate regulatory
agency, or respirator supplier, whichever is lowest.
If oil particles (e.g. lubricants, cutting fluids, glycerine, etc.) are
present, use a NIOSH type R or P filter.
For emergencies or instances where the exposure levels are not known, use a
full-facepiece positive-pressure, air-supplied respirator.
WARNING: Air-purifying respirators do not protect workers in
oxygen-deficient atmospheres.
B. Skin Protection :
Wear impervious protective clothing, including boots, gloves, lab coat,
apron or coveralls, as appropriate, to prevent skin contact.
C. Eye Protection :
Use chemical safety goggles and/or full face shield where dusting or
splashing of solutions is possible. Maintain eye wash fountain and
quick-drench facilities in work area.
V. Disposal Considerations :
Whatever cannot be saved for recovery or recycling should be handled as
hazardous waste and sent to an approved waste facility. Processing, use or
contamination of this product may change the waste management options. State
and local disposal regulations may differ from federal disposal regulations.
Dispose of container and unused contents in accordance with federal, state
and local requirements.
TOXICOLOGY :
I. Experimental Toxicology :
Oral rat LD50 : 25 mg/kg.
Skin rabbit LD50 : 14 mg/kg
II. Acute Effects :
A. Inhalation :
Corrosive. Extremely destructive to tissues of the mucous membranes and
upper respiratory tract. Symptoms may include :
- sore throat
- coughing
- shortness of breath
- and labored breathing
Higher exposures may cause pulmonary edema.
B. Ingestion :
Corrosive. Swallowing can cause severe burns of the mouth, throat, and
stomach, leading to death. Can cause sore throat, vomiting, diarrhea. May
cause violent gastroenteritis, peripheral vascular collapse, dizziness,
intense thirst, muscle cramps, shock, coma, abnormal bleeding, fever, liver
damage and acute renal failure.
C. Skin Contact :
Corrosive. Symptoms of redness, pain, and severe burn can occur. Dusts and
strong solutions may cause severe irritation. Contact with broken skin may
cause ulcers (chrome sores) and absorption, which may cause systemic
poisoning, affecting kidney and liver functions. May cause skin
sensitization. May be absorbed through the skin; symptoms may parallel
ingestion.
D. Eye Contact :
Corrosive. Contact can cause blurred vision, redness, pain and severe tissue
burns. May cause corneal injury or blindness.
III. Chronic Effects :
Repeated or prolonged exposure can cause ulceration and perforation of the
nasal septum, respiratory irritation, liver and kidney damage and ulceration
of the skin. Ulcerations at first may be painless, but may penetrate to the
bone producing "chrome holes."
IV. Aggravation of Pre-existing Conditions :
Persons with pre-existing skin disorders, asthma, allergies or known
sensitization to chromic acid or chromates may be more susceptible to the
effects of this material.
V. Pregnancy :
A. Effects on development :
It has an embryotoxic and/or foetotoxic effect in the animal.
It crosses the placenta in the animal.
B. Effects on reproduction :
It may cause effects in the testicles of animals.
C. Data on mother's milk :
There are no data concerning its excretion or detection in mother's milk.
VI. Carcinogenic Effects :
Known to be a human carcinogen.
VII. Mutagenic Effects :
Demonstrated mutagenic effects in the animal or suspected in man.
VIII. Sensitization :
This product causes respiratory and skin sensitization.
FIRST AID MEASURE :
I. Inhalation :
Remove to fresh air. If not breathing, give artificial respiration. If
breathing is difficult, give oxygen. Get medical attention immediately.
II. Ingestion :
If swallowed, DO NOT INDUCE VOMITING. Give large quantities of water. Never
give anything by mouth to an unconscious person. Get medical attention
immediately.
III. Skin Contact :
Immediately flush skin with plenty of water for at least 15 minutes while
removing contaminated clothing and shoes. Get medical attention immediately.
Wash clothing before reuse. Thoroughly clean shoes before reuse.
IV. Eye Contact :
Immediately flush eyes with plenty of water for at least 15 minutes, lifting
lower and upper eyelids occasionally. Get medical attention immediately.
ECOLOGICAL INFORMATION :
I. Environmental Fate :
When released into the soil, this material may leach into groundwater. When
released into water, this material is not expected to evaporate
significantly. This material may bioaccumulate to some extent. When released
into the air, this material may be removed from the atmosphere to a moderate
extent by wet deposition.
II. Environmental Toxicity :
No information found.
EXPOSURE LIMIT IN QUEBEC :
Valeur d'Exposition Moyenne Pondérée (VEMP) :
0,05 mg/m³ (expressed as Cr.)
References :
1. Chemical Hazards of the Workplace, Proctor & Hughes, 4th edition.
2. Clinical Environmental Health and Toxic Exposures, Sullivan & Krieger;
second edition.
3. CSST-Québec, Répertoire Toxicologique.
4. J.T. Baker, MSDS, Potassium Dichromate
5. Occupational Medicine, Zenz C., third edition.
6. Sax's Dangerous Properties of Industrial Materials, Lewis C., 10th
edition.
7. Toxicologie Industrielle et Intoxications Professionnelles, Lauwerys
R.R., 4th edition.
----- Original Message -----
From: "Ron Roy"
To:
Sent: Saturday, December 10, 2005 4:20 PM
Subject: Re: potassium di chromate
> Hi Annapoorna,
>
> Just so you know - Chromates are potent animal carcinogens - strontium
> chromate being the strongest.
>
> RR
>
>
>>hi
>>any glazes with potassium di chromate or potassium chromate.
>>thank you
>>annapoorna
>
> Ron Roy
> RR#4
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
> Phone: 613-475-9544
> Fax: 613-475-3513
>
> ______________________________________________________________________________
> 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.
>
>
Ivor and Olive Lewis on mon 12 dec 05
Dear Annapoorna Sitaram,=20
Before using this Chemical Compound, please consult the product data =
sheets.
They are known to cause Cancer. Both compounds are Oxidising agents and =
under some circumstances can explode violently. Ammonium Dichromate is =
also very suspect.
No doubt there are people who wish to stain or paint on green or bisque =
porcelain that use these chemicals because they are soluble in water. =
However, if you wish to colour a glaze use Chromium try the Sesquioxide =
in very small amounts. Wear Gloves, a Mask and do not let the powder get =
into any cuts or open wound.
The best way to get good consistent green glazes is to use copper =
compounds (Black oxide or Green Carbonate) in oxidation firings or =
better still, Ceramic Stains.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Louis Katz on mon 12 dec 05
Annapoorna,
Read
http://ceramic-materials.com/cermat/education/182.html by
Edouard Bastarache
You can read about Potassium Dichromate at the above link. But from my
poorly educated reading potassium dichromate is a hexavalent chromium
compound and as such can be absorbed through the skin even if the skin
is unbroken.
You should read the whole webpage. It apparently does not take much
potassium dichromate to be quite harmful. The page will make your skin
crawl.
Louis
| |
|
