htpp://www.alisdairkettlespotterysupplies.com - ALISDAIR KETTLES POTTERY SUPPLIES
ALL POTTERY SUPPLIES AND REPAIRS
FREQUENTLY ASKED QUESTIONS.
Why is my earthenware glaze crazing?
Mismatch of the thermal expansions of glaze & body (insufficient glaze compression).
What is the difference between a stain and an underglaze & on-glaze colours?
An underglaze colour is finer ground glaze stain and normally contains a frit or flux addition. An on-glaze is a fusible colour where all the constituents are melted together and finely ground
What is the difference between Earthenware & Stoneware?
Earthenware is porous and typically white firing. Stoneware is semi or vitreous and darker firing)
Can I use Earthenware brush on glazes on Stoneware?
No – the thermal expansion is not suited to a stoneware body and likely to craze
What raw materials and oxides make a glaze not food safe?
Lead, Cadmium, Selenium, Arsenic, Antimony, Barium, Zinc, Nickel, Cobalt. NOTE that limited additions of these compounds are permitted if introduced in the correct form. SEEK ADVICE to be sure.
Can I mix glazes (i.e. yellow and blue to make green)?
Yes – certainly with pastel coloured glazes. A TRIAL would be recommended before commencing.
Do I need 3 phase electrical supply to run a front loading kiln?
Not necessarily. but probably.
What is Pinholing?
Pinholing is caused by air entrapment or body impurities
What is Thermal Shock?
Ware heated or cooled too quickly and the body cracks or spilts as a result.
What is the difference between Tin and Zircon opacified glazes?
Tin glazes are blue white in colour, offer a broader firing range than Zircon glazes and require approximately half the oxide addition when
compared with Zircon.
Why does my Kiln smell during the first stages of the firing?
This is typical, this emanates from moisture, the body organics and glaze binders.We strongly recommend that the kiln is used in a well
ventilated room / area
At what temperature should I fire the kiln to for the first firing and following element replacement?
1100˚C – this will form a protective coating on the surface on elements and conditions the brickwork to the firing cycle
At what temperature can I open my Kiln after the firing cycle?
Not above 100°C – CHECK your controller
An element has come out of it’s groove – what should I do?
Dependant on the severity the element can be pushed back in and re-pegged if unsure contact ALISDAIR KETTLES POTTERY SUPPLIES we can fix it for you.
The bricks on my kiln are cracking?
These cracks are inevitable, and are referred to as expansion / contraction cracks which reflect the firing process. They do not affect the firing
performance and are best left alone
Can I fire the Kiln unattended?
No. As with all electrical equipment it is advisable to be present during the critical stages of the firing.
Where can I get clock movements and hands for making pottery clocks ?
We stock them (see other materials).
I am not sure what a slab roller does ?
A slab roller is a handy machine for rolling clay to a certain thickness for a variety of processes, it is a great timesaver and help for anyone in pottery.
I have heard rumours that Plaster of Paris must be used with care is this true ?
Like all materials you must apply caution to their use. If not sure seek advice. But Plaster of Paris in particular reaches high temperatures when setting.You must never place limbs or naked skin into this material at any time.