Questions potters actually ask

Materials and firing

What does “cone 6” actually mean?

A pyrometric cone measures heatwork — the effect of temperature and time together. Cone 6 is
roughly 2232 °F (1222 °C) at a rise of 108 °F per hour in the last hour, but fire faster
or slower and the temperature at which that cone bends moves. That is why we list clays and glazes by
cone rather than by a single temperature: the cone is what the clay and the glaze are actually
responding to.

Can I use a cone 6 glaze on a cone 10 clay body?

Usually yes, but the body will not be vitrified at cone 6, so the finished piece can stay porous and
the glaze fit may be poor — crazing shows up weeks later. Match the body’s range to the glaze’s range,
and when in doubt fire a test tile before you commit a kiln load.

Why does my glaze look nothing like the picture?

Application thickness, the clay body underneath, the firing schedule and the cooling rate all change a
glaze. A glaze photographed on a white porcelain test tile at cone 6 with a slow cool can be a different
colour on a dark stoneware body fired fast. Our listings state the body and schedule each tile was fired
on, and where a glaze needs a slow cool to break we say so.

How much clay do I need?

A rough working figure: a 25 lb box throws about 12–15 mugs, 6–8 medium bowls, or 4–5 dinner
plates, before trimming losses. A class of 20 students doing a six-week hand-building unit typically goes
through 200–300 lb. Order a little over: clay keeps if it is sealed and kept off a cold floor.

My clay arrived hard / dry at one end. Is it ruined?

No. Slit the bag, wrap the block in a wet towel inside a sealed bin for two or three days and wedge it
back together. If a box arrives genuinely dried out or the bag is split, tell us within five days and we
will replace it.

Do you sell zircon opacifier?

Yes — zirconium silicate opacifier is a standard stock item in the glaze materials department, in
several mesh sizes. It is the most common way to turn a transparent base glaze into a reliable opaque
white, and it is the mineral this company is named after.

Shipping and freight

How fast do you ship?

Orders pack in 1–2 working days; parcels arrive 1–5 working days after dispatch. Freight depends on
the lane and the appointment, usually 3–10 working days.

Why is a kiln freight and not parcel?

Weight and fragility. A 7-cubic-foot kiln is 300–450 lb on a pallet; no parcel carrier will take
it, and one that did would destroy it. Freight also means you get a delivery appointment rather than a
driver leaving a crate in the rain.

Will the driver bring it inside?

No — standard freight is curbside. Liftgate and inside delivery can be added to a quote before
dispatch if you ask. Plan for two or three people and an appliance dolly, and measure your doorway before
the kiln arrives, not after.

Will my clay freeze in the winter?

It can. Frozen clay thaws out fine once or twice, but repeated freeze–thaw makes it short and the bags
brittle. Between December and February we will hold or insulate a moist-clay shipment on request, at no
charge — just say “winter hold” in the order notes.

Do you ship outside the United States?

Not at present. We ship within the US, including Alaska, Hawaii and the territories, where those are
quoted before dispatch.

Ordering, accounts and payment

Do you have a minimum order?

No minimum. Ground parcels are a flat $9.95 and free over $199, so there is no penalty for ordering a
single tool.

Do you supply schools and community studios?

Yes, and a good deal of what leaves here goes to classrooms. Email us with your typical monthly
volume for pallet pricing on clay, standing stock for term schedules, and purchase-order invoicing once
an account is open.

Can I pick my order up?

By arrangement. We are a warehouse rather than a showroom, so email first with the day you want to
come and we will have it ready.

What will the charge look like on my statement?

SQ *ZIRCON SUPPLY CO.. If that looks unfamiliar, email us before contacting your bank and we will
identify the order the same day — see payment and security.

Can I return clay I opened?

No. Once a bag of clay or a bucket of glaze is opened we cannot verify it or resell it. Unopened,
unfired goods can come back within 30 days — the details are on the returns
page.

Safety

Do I really need a respirator?

For dry materials, yes. Silica dust is the serious hazard in a ceramics studio and the damage is
cumulative and permanent. Use an N95 at minimum for handling dry powders, mix in front of local exhaust
or outdoors where you can, wet-mop rather than sweep, and keep dry materials out of any room where people
eat.

Is a glaze “food safe” if it says so?

A glaze is only food safe as you fired it. A manufacturer can state a glaze is formulated to be food
safe at a given cone; if you fire it short, apply it too thick, or add a colourant to it, that statement
no longer applies to your piece. Anything you intend to sell for food use should be leach-tested by a
laboratory.

Can you send the safety data sheet before I buy?

Yes. Email support@zirconsupply.store with the material and we will send the current SDS the
same day.