Sieve your powdered glaze into water through a 60-80s mesh sieve. For unleaded glazes, mix 100g of powder with 50ml of water. For leaded glazes, mix 100g of power with 45ml of water.

Some glaze ranges such as Amaco Teachers Palette are specifically designed to be intermixable; other glazes might mix but would not necessarily achieve an intermediate colour. Mixing glazes could alter qualities other than colour, texture and firing temperatures could be affected; always test before going into production.

Yes, if they have been mixed to the correct consistency.

Mismatch of the thermal expansions of glaze & body
(insufficient glaze compression), the glaze may not be suitable for the particular clay. In simple terms, when the pot has cooled and contracted after the firing the glaze is smaller than the clay body and is unable to sustain the tension put upon it. Often this is caused by underfired bisque, so it is important to check the temperature of your bisque firing.

If stoneware clay is fired to maturing temperature it will be difficult to apply brush-on glazes as the surface will not be porous, if this can be achieved then the earthenware glaze might fire successfully but there is a risk of crazing. The glaze must be fired to its specified temperature. Some stoneware clays are dual purpose and can be used at earthenware temperatures.

Stains are used to colour clay and glaze and are very strong colours. Underglaze colour is finer ground glaze stain and normally contains a frit or flux addition. Underglaze colours may also be used to colour glazes and clays but are primarily designed for applying to ware, either greenware or bisque which is subsequently glazed usually with a transparent glaze. They can also be used on top of a white glaze before firing, (Majolica technique). On-glaze colours are fusible colour where all the constituents are melted together and finely ground, they are applied on top of a fired glaze and are typically fired to 700°C/800°C. They are also called China paints or enamels.

Where toxic materials are used in Potterycrafts glazes they are present in a safe form where they are chemically bonded in "fritting" or "encapsulation" processes. These processes render the substances "not bio-available" and therefore safe to use in making and after firing. For example, where lead is present in "low sol" or fritted form the health & safety Executive do not require it to be to labelled toxic. If fired correctly most proprietary glazes will be food safe. Glazes with a textured, crazed or a very matt surface may not be food safe as the surface can harbour bacteria. If in doubt about a specific glaze, or if you have concerns, please contact our technical advice department. For potters mixing their own glazes the following substances are considered toxic however most of them are no longer available except in fritted or encapsulated form: Lead, Cadmium, Selenium, Arsenic, Antimony, Barium, Zinc, Nickel, Cobalt.

The first firing, (bisque or biscuit) should be quite slow
to avoid moisture trapped in the clay from turning to steam which will shatter the ware. If the controller has more than two heating ramps the best approach is to fire to around 80°C at a rate of 80°C per hour and then soak at that temperature for one hour. The second ramp should then be 100°C per hour up to 500°C the third heating ramp can be faster, 150 or 200°C per hour to the top temperature. If there are only two ramps make the first around 70°C. Fire even
slower for large pieces. Glaze firing can usually be at a faster rate; typically, 120/150°C per hour is acceptable. Make the first set point no lower than 600°C, after this temperature it is safe to go faster 150/250°C to top temperature. Larger pieces should be fired more slowly.

Earthenware is fired at lower temperatures usually not more than 1180°C. At this temperature the clay remains porous, and the glaze will be a separate layer adhering to the surface. Stoneware is fired to higher temperatures, maturing the clay and glaze at the same time. The glaze interacts with the clay forming an integral glaze/clay layer. Stoneware biscuit firings are usually around 1000°c and glaze firings 1230°C to 1300°C.

Battwash is a multi- purpose refractory mixture of very fine ground zirconia and clay. This blended material is dispersed in water to produce a thin slip of cream-like consistency. mix the batt wash adding it into water and creating a single cream consistency. A thin layer of this is then painted by brush, or roller. it is best for the first use to apply 3 consistent coats allowing time between each for them to dry fully before applying further layers. it is best applied in alternate directions to give best coverage, coat once, turning the shelf or brush direction by 90 degrees onto refractory kiln shelves (batts) and this reduces the risk of pottery sticking to the shelves during firing because of glaze runs or poorly wiped feet. This layer does not need to be fired and fixed in place before using the refractory batt, ware can be placed directly on to the unfired layer. If the layer is damaged by excessive glaze drips, then the batt should be scraped clean and a new layer of batt wash applied.

The choice of clay depends on your specific project and the firing method you use. We recommend consulting our clay guide on the website to help you make the best choice.

It is usually possible to run any of our kilns, top or front loader up to 13kilowatt size from a domestic 100-amp single phase supply. This would give you a kiln up to about 8 cubic foot 225 litres. At 13kW you would require 60amp supply which is the maximum recommended for a single appliance running off a 100amp supply. It is essential to have your supply checked by a qualified electrician before purchasing a new kiln, if in doubt we can speak directly to your electrician.

Small round, smooth edged holes in the glaze surface can be caused by gases from impurities in underfired bisque or slightly underfired glaze. In re-fired ware such as China painting it is caused by moisture absorbed into the body being forced out during the firing.

When ware is heated or cooled unevenly stresses develop causing cracks to occur, this is because of different rates of expansion or contraction within the piece. Heating and cooling more slowly reduces the temperature differential as heat is conducted through the item.

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.

Organic, vegetable matter present in clays and suspending agents and binders in glaze start to burn away at quite low temperatures and can produce strong smelling fumes. This will die away as the kiln reaches
500/600°C. With most firings the level of toxicity in fumes is very low, on a par with fumes present from traffic in a high street; however, working in a room where a kiln is firing is not recommended. If you would like advice on kiln ventilation, please call.

New elements fired to around 1100°C in an empty kiln will develop the oxide layer on the surface of the wire more quickly and should improve element life. If the glaze or clay being used produces aggressive fumes such as fluorine then this is worth doing, with usual materials the benefit is marginal.

If the door is opened when the kiln is above 200°C there is a risk of cracking the pottery because of uneven cooling at the critical point of sudden contraction. This is due to crystobalite inversion, a chemical change occurring between 280°C and 220°C. Although safer for the pottery below 200°C, beware of a risk of burning until the kiln has cooled to room temperature.

Moving or bending an element can result in it snapping as they become very brittle with firing. First heat the element to red heat with a blow lamp and then bend to shape with long nosed pliers. Staples made of element wire might be helpful to hold it more securely.

New designs, materials and methods of construction are minimising this problem however some cracking may occur because of expansion/contraction stresses. Opening the kiln too early will increase the risk of bricks cracking. As long as they are not structural even severe cracking will not affect the firing performance.

Potterycrafts latest kilns all have over-temperature and anti-power surge devices which make them safe to fire, but we advise that there should be some supervision during the firing especially at the end when the kiln completes its firing.

Gel Coat resin has an approximate coverage of 450gm², a 1kg tin should give you just under 2 square metres.

As a general rule you should go by the ratio of 2 to 1 by weight; for example when using light chopped strand mat (300gm²) you will need around 600 grams of resin to wet it through.

For a true colour - our range of Polyurethane Pigments can be used. You could also use the Acrylic Paints, but the colour produced will not be strong but more of a pastel shade. No product is suitable for colouring
RTV-101.

Extra layers added to the mould should be applied when the first layer is still just slightly tacky.

If kept wrapped in damp cloths and sealed in a plastic bag, moulds will normally keep for 2 to 3 days. Ideally though, Alginate moulds should be used as soon as possible as they will begin to shrink and distort as the water dries.

You can try painting a solution of water and Sodium Bicarbonate (Baking Soda) onto the set Alginate before adding additional layers.

Our Earth Colours are ideal for this.

The 23¾ carat; the higher the gold content, the better.

Normally, it will make up to two face moulds.

No, not really; it will not last well at all. However, if you use Basic Alpha with our Plaster Polymer it will be very weather resistant and should last several years.

Delivery times depend on your location and the type of product ordered. Generally, orders are shipped within 2 to 5 business days. For more details, please refer to our shipping page.

Once your order is shipped, we will send you an email with a tracking number. You can use this number on our website or the carrier's website to track your package.