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These safety guidelines are meant for use by ceramic artists and crafts
people who create, or recreate, in a limited number, largely by hand,
works that may or may not have a practical use, but in which aesthetic
considerations are paramount. These guidelines are meant for use in hobby
and contemporary ceramic studios. Commercial manufacturing facilities
may use these guidelines as a supplement to other safety information,
such as material safety data sheets or OSHA hazard communication programs.
However, these guidelines may not cover every safety concern found in
commercial manufacturing facilities. Material Safety Data Sheets MSDS
(Material Safety Data Sheets) are available on our website.
Non-Toxic vs. Lead Free:
A non-toxic glaze is one that, in its liquid or unfired state, has been
certified by a qualified toxicologist to present neither acute (immediate)
nor chronic (long-term) health hazards. Toxicity is the main issue, not
lead. A glaze is either non-toxic or toxic. So if a product is non-toxic,
it is safe not only from lead, but also from other potentially harmful
materials, depending on the toxicologists' criteria. This is because when
products are tested, they are tested for much more than lead. Always read
your jar or container label before using and look for the non-toxic logo.
If your product is not non-toxic, the label will have a warning statement
and will describe possible adverse health hazards.
Non-toxic glazes are sometimes referred to as non-leaded glazes. This
is because non-toxic glazes are made without the addition of lead.
Dinnerware or Food Safe:
Dinnerware safe and food safe are terms used interchangeably to note glazes
which, when fired properly, are safe for use on ceramic items that may
come into contact with food or drink (i.e.: mugs, bowls, plates, pitchers,
platters, etc.).
A piece is deemed to be dinnerware or food safe if, after it is fired
properly, it does not release enough potentially harmful material above
limits set by the FDA.
Some clear glazes that contain lead may only be dinnerware or food safe
when fired to the proper temperature. This is because a glaze may contain
materials that are potentially harmful in the liquid state, but when properly
fired, the glaze does not "release" such materials above the
safety limits set by the FDA. If under fired, it may not pass federal
regulations.
Glazes, which produce a cracked, textured or pitted surface, are not
recommended for dinnerware items because these surfaces could potentially
trap bacteria. Again, read your jar or container label to see if your
glaze is dinnerware or food safe.
Proper firing of food-safe glazes is critical. Use pyrometric shelf cones
on the kiln shelves to ensure that the pieces are fired hot enough, even
if the kiln is electronically controlled or has an automatic kiln sitter.
Always fire in accordance with manufacturer's instructions. If crazed
or under fired, these glazes may not be food safe. Improperly fired lead-containing
glazes may leach excessive levels of lead.
Product Labeling:
Read labels with care. In ceramics, as in all areas of human activity,
proper usage of products ensures safety. Misuse of products may expose
the ceramist to potentially harmful substances. Care should be taken to
read all label instructions before using a product. Labels will identify
any hazardous ingredients and their hazards, provide first aid instructions
and give recommendations on how to use safely and prevent excessive exposure.
Gare's products are labeled for material safety. We list toxicity information
to meet the standards for health labeling established by the Chronic Hazard
Labeling Standard, ASTMD 4236, and the U.S. Labeling of Hazardous Art
Materials Act (LHAMA). All products are labeled with either a Non-Toxic
seal or a Caution Read Warning seal. If you are using a product that has
a Non-Toxic seal, the product has been reviewed by a certified toxicologist
and deemed to have no health risk associated with the proper use of that
material. A product that is marked with a Caution Read Warning will have
a health warning and information regarding its use.
Microwave/Oven Safe:
Different manufacturers have various opinions on this issue. The facts
of the matter are many people use them in the microwave and oven without
any problems, but some do have problems.
The problem is the ceramic ware, or clay body, plays such an important
role in this issue. Unfortunately, in our ceramic industry, we are dealing
with a low fire earthenware body that is very porous and not as durable
as some higher fire clay bodies.
With such a porous body, water can be absorbed into the ware, for example,
through the stilt marks. When your piece is heated to a high temperature,
water that is absorbed into the ware may convert to steam and crack or,
in extreme cases, explode your piece. You may also get some crazing simply
due to thermal shock and we do not recommend crazed pieces be used for
dinnerware since bacteria may get trapped in the cracks.
There may be other factors at work as well. How the bisque firing and
glaze firing are handled can affect the "fit" of the glaze to
the body. For example, if the bisque is improperly or under fired, the
glaze may not "fit" the body as it should. When heated and/or
cooled rapidly through the microwave or oven, you may incur crazing or
in extreme cases glazes popping off.
Do people do it successfully with glazes on earthenware bodies? The answer
is yes. Many people do use their pieces in the microwave or oven successfully.
For example, some small commercial users and experienced ceramists suggest
firing the bisque to cone 03 and in some cases to 02. They suggest by
firing it hotter, it makes the ware less porous, thus eliminating the
risk of absorbing water. Firing earthenware hotter will make it less porous,
but with the earthenware bodies we have in our industry, you run the risk
of having the ware slump, sag or get out of shape if you fire it that
hot. Again, some people swear by this technique and say they have never
had any problems.
Others say they fire the bisque and glaze firing as directed on the jar
and have never had any problems.
Others have said that about once a year, when my pieces craze, I simply
refire them to the recommended glaze firing and the pieces look like new
again.
The fact is you have to determine for yourself how you want to handle
this issue in your studio. The bottom line is, some people do get away
with using their pieces in the microwave or oven. Some do not.
Dishwasher Safe:
Because most bisque in our industry (excluding stoneware) is earthenware
bisque, we recommend hand washing rather than using a dishwasher. The
porous nature of earthenware can lead to water being absorbed through
stilt marks. This can lead to crazing of the ware. Crazing could potentially
trap bacteria and would not be considered to be food safe. Earthenware
is also prone to chipping when washed in a dishwasher. Like any handmade
treasure, we recommend hand washing your artwork and handling it, as you
would fine china.
Housekeeping:
Common sense cleanup and maintenance of the work area is a must for people
working with ceramics. It is strongly recommended that the following rules
be observed.
Whether or not you use non-toxic or regular glazes, we suggest the following:
- Wet mop floors daily to control dust; do not sweep.
- Keep working surfaces and shelves clean by wiping down with a wet
sponge as necessary.
- Prevent dust before it occurs. Prevent any build-up of clear glaze
in dipping area by wet mopping daily and cleaning racks, work surfaces
etc. with a wet sponge, rinsing the sponge frequently.
- Have only hard surfaces and floors that can be wet mopped.
- Clean up spills when they occur.
- Have customers work on paper for easy clean up.
- Meet with your employees on an as needed basis to explain your housekeeping
rules.
- Post safety signs to keep employees focused.
- No smoking, eating or drinking in glazing and kiln areas.
- Clearly mark Employee Only areas.
Dust Control:
Dust control measures are necessary for any operation, which may generate
dust. This includes the creation of dust from dipping glazes that have
dried on work surfaces, mixing of dry ceramic materials, grinding, drilling
or sanding greenware or bisqueware. Keep working surfaces and shelves
clean by wiping down with a wet sponge, rinsing the sponge frequently.
Clean up spills when they occur. Do not allow to dry.
- Wet-mop floors to control dust; do not sweep.
- Vacuuming can be used for dust clean up but the vacuum should be equipped
with HEPA-type exhausting filter that traps particles 0.3 micron in
diameter or larger.
- Work over a linoleum or sealed floor. All work surfaces should be
non-porous. These measures allow easy cleanup of spills and dust and
prevent tracking.
- Do not wear contact lenses when working in dusty environments. Dust
particles may become trapped between the lens and the surface of the
eye, and these small particles can scratch the eye.
- Wear a smock or apron when working with hobby ceramic materials in
order to prevent contamination of clothing or your home. The smock or
apron should be left in the work area. Either launder regularly or use
a disposable vinyl apron. When laundering work garments, wash them separately
from other clothes.
Personal Hygiene:
Ceramic products and materials can be handled very safely if we keep in
mind that materials should not be ingested or dust inhaled. Do no smoke,
eat or drink when working with potentially hazardous ceramic materials.
Such practices can transfer hazardous substance to the mouth or leave
substances such as salt and oil on the work surfaces and thus ruin your
glazes. Always wash hands thoroughly when you are through working with
hazardous materials, even after removing gloves. Be sure to put away materials
where small children cannot reach them. Do not use any utensils that will
later be used in the kitchen. If there is an accidental ingestion, call
a doctor or your local poison control center, listed with emergency numbers
in the front of most telephone books.
Do not handle materials used to produce ceramics when you have open cuts
or wounds.
Remove jewelry and use vinyl or lined rubber work gloves when glaze dipping
or loading kilns with products finished with leaded glazes.
Kiln Safety:
Insulated gloves should be worn when handling a kiln after the venting
period, as the handle will be hot. Never touch the outside of a kiln (other
than the control panel) when it is turned on as the kiln surface temperature
may be very hot.
Dark-shaded glasses from a safety supply house (shade number 1.7-3.0)
are recommended when looking into kiln peepholes to protect your eyes
from radiant heat. Normal sunglasses are inadequate for this purpose.
Protective glasses also allow you to see witness cones more clearly.
Install electric hobby kilns in accordance with local electrical and
fire safety codes and in accordance with manufacturers' suggested installation
instructions. A qualified electrician must perform installation.
For used kilns, contact manufacturers for installation instructions.
Electric hobby kilns heat ceramic pieces to a very high temperature.
Any electric appliance can present an electrocution hazard if operated
in contact with water. Do not operate a kiln in a wet area. To prevent
burns or damage to your work, do not remove hot pieces from the kiln.
Do not allow children near the kiln.
Do not plug in or unplug the kiln unless the circuit is off. Turn all
switches to OFF before loading or unloading the kiln. Do not open the
lid with the kiln turned on.
Do not leave papers or combustibles around the kiln, or place objects
on the kiln while firing. Always unplug the kiln while making any repairs.
Exterior of kiln will become very hot during a firing cycle. Do not allow
customers near the kiln.
Properly ventilate kiln to outside.
Do not unload kiln until kiln is cool to the touch (150°F) and the
pieces can be easily touched by hand. Removing hot pieces presents risks
of burns or fires or crazing of glazed surfaces.
When unloading a kiln, be careful of the stilt marks on glazed ceramic
pieces. They can be sharp and should be smoothed as soon as possible with
a grinding wheel or stone. Wear safety glasses while grinding off stilt
marks.
Vacuum kiln interior on a regular basis in accordance with manufacturer's
instructions.
Kiln Ventilation:
Vent electric kilns properly to Control Dust and Fume Exposures. Use indoor
kilns with an exhausting canopy type hood, down draft kiln vent or exhaust
fan to assure adequate cross ventilation.
NOTE: Warning- Fossil fuel kilns (oil, gas, coal, wood, etc.) must have
outside ventilation. For these kilns the user should contact the kiln
manufacturer and a local, licensed heating, ventilation and air-conditioning
contractor for proper installation. Qualified professionals following
manufacturers' installation procedures and directions must install all
hoods and ventilation equipment. To determine the appropriate ventilation,
it is recommended that a local licensed heating, ventilation and air-conditioning
contractor be consulted.
Exhaust ventilation hoods out of doors. Provide good dilutional (general)
ventilation and an adequate make up air source to assure efficient hood
operation.
HAC mechanics have equipment for accurate testing of the adequacy of
hood
ventilation. The need for hood repair or filter changes can be checked
by lighting a match at your work station in front of the hood. If ventilation
is adequate, the hood draw should blow the match out.
Always turn on your kiln hood or vent prior to loading to prevent ceramic
glaze dust exposure.
Pregnancy Issues:
Women who are pregnant or considering pregnancy should only work with
lead-containing glazes in a supervised hobby ceramics studio. Such individuals
should avoid dipping lead-containing glazes or kiln loading.
Pregnant women or women contemplating pregnancy who are active ceramists
should notify the physician of their work with ceramic products.
Sprays, Solvents & Overglazes:
These products are easy to use safely and will present no problems as
long as these three important rules are observed: keep out of reach of
children, use in a well-ventilated area, and clean up after use. Prior
to using spray aerosols, solvents or overglazes, read the warning labels
and safe use instructions on the containers. Over exposure to solvent-containing
ceramic materials can result in symptoms of eye or nose irritation, headaches,
dizziness, nausea and confusion.
Containers should be kept tightly closed when not in use.
Aerosol sprays, solvents and solvent-based overglazes should be used
out of doors, in a locally exhausting hood or spray booth or with a window
exhaust fan to assure adequate cross ventilation.
Glaze Dipping:
- Accidental ingestion - Call doctor or local poison control.
- Wash hands and arms thoroughly after working with glaze.
- Rinse mouth or eyes with water if splashed with glaze.
Spraying Glazes:
We do not recommend the spraying or airbrushing of any glazes. Do not
spray or airbrush any product labeled as " Not for spray application".
Gare glazes are designed for brush application. Spraying or airbrushing
of glaze might allow you to inhale lead or other harmful materials. Commercial
ceramic facilities that do spray lead-bearing glazes must conform to OSHA
regulations that include the use of respirators, medical monitoring, hygiene
guidelines and other safety equipment. Contact OSHA for further information.
Safety Rules:
Regular blood lead testing should be done for any individual who works
routinely dipping with lead-containing glazes or loading kilns.
Keep these common-sense safety rules in mind and remember to observe
them. A list of studio safety rules might include some, or all, of these
pointers:
- Keep work surfaces and shelves clean by wiping down with a wet sponge.
- Clean up spills when they occur. Do not allow to dry.
- Work on a newspaper or paper towel for easy cleanup and disposal.
- Do not smoke, eat or drink when working with hazardous ceramic materials.
- Wash your hands thoroughly when you are through working.
- Use a smock when working with ceramic materials.
- Keep children away from kilns and out of glaze dipping rooms.
- Children should not use lead-containing glazes or other hazardous
ceramic materials.
- Do not mix lead-containing food-safe glazes.
- If pregnant or contemplating pregnancy, tell your physician about
your work with ceramics.
- When using solvent-containing ceramic materials:
- Work out of doors, in a locally exhausting hood or with an exhaust
fan.
- Do not use or store near kilns, other heat sources or an open
flame.
- Dispose of used rags in an air-tight metal container or under
water.
- When work generates ceramic dust:
- Use a NIOSH-approved respirator for dust.
- Work in a locally exhausting hood.
- Do not track dust from the studio to areas where children may
play.
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