How to Buy Ceramic Glaze

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How to Buy Ceramic Glaze

Glaze is an outer coating that is fused to the ceramic to make it safe, useful, and beautiful. Depending on the type of glaze, it can waterproof, strengthen, add colour, create patterns, or remove colour. The treatment can turn a porous, matte surface into a smooth shiny one, completely changing the look and function of the ceramic pottery.

Ceramic glaze is used to create many things such as plates, mugs, vases, and bowls. Originally glaze was only used to waterproof dinnerware, because without the coating, ceramic just soaks up liquids. The process of glazing takes training and practice. Not only is the technique difficult to learn, but glaze can be highly toxic. It is important to select a glaze that is appropriate to the project. For example, there are non-toxic glazes which are made to go on dinnerware so that harmful toxins are not consumed. Because of this, understanding what types of glazes are available, and which ones to purchase is important.

History of Ceramic Glaze

The discovery of ceramic glaze came from China around 1751 - 1111 BC. They built kilns that trapped the heat inside to produce temperatures. While using these kilns, they found out that wood ash melts into glaze when heated to hot enough degrees. The potters then mixed the ash with lime or other dirt to create glazes with different colours such as yellow and green.

General Ceramic Glaze Terms

In order to choose the proper glaze for the project, there are some germs that consumers need to understand. It is important to always read the label of the product before purchasing, but in order to do so, people have to understand the industry terms and classifications.

Glaze Surfaces

The terms related to the surface refer to whether the glaze is shiny, dull transparent, or opaque. In other words, these terms refer to how the glaze looks when applied to the surface of the ceramic.

Glaze Surface Texture

Description

Gloss

Highly shiny and smooth with a reflective surface

Satin

Has a smooth sheen that is not reflective, but is smooth

Matte

Has no gloss whatsoever and has a flat, dull appearance; reflects very minimal shine

Dead Matte

Completely flat and reflects no light or shine

Opacity

Indicates how transparent the glaze is; for example, some are clear, while others are coloured; opacity can be clear, transparent, semi-transparent, semi- opaque, or opaque

The chemicals used to determine the surface texture can be harmful. Sometimes the raw materials used in glazes are changed for safety reasons. If this is the case, the label usually indicates that it is the new, safer version.

Ceramic Glaze Safety

As mentioned before, the most important aspect of choosing a glaze is figuring out how safe it is, and how to work with it. The biggest risk is that the toxins could penetrate a serving dish and then get into the food or liquid. Every glaze has to be analysed independently by a licensed toxicologist who determines how the product is labelled.

The ones which are labelled as being non-toxic, are then examined again to determine if they are safe enough to be around foods. These are the main categories in which glazes are placed into.

Glaze Safety Labels

Description

Dinnerware and Food Safe

Once the glazed is fired to the ceramic, per the product label instructions, it is safe to be in contact with food

Health Caution

Health caution labels refer to the glaze while it is still in the jar

In its unprocessed form, it may be harmful; this has nothing to do with its safety rating after it has been fired and hardened

Non-Toxic

This also refers to the unused glaze in the jar

There are no toxic ingredients, but larger quantities could still be harmful to humans

Not for Dinnerware or Food Use

This indicates that the fully finished product is not intended to be used on dinnerware or around food

The glaze contains harmful chemicals in it that could contaminate the food

Certain forms of ceramic glazes usually always have the same safety labels. For example, stroke and coat glazes are dinnerware safe. Crackles and crystalites are non-toxic, as well as dinnerware safe. However if the hardened glaze cracks off flakes into the food, it could be hazardous. C-109 dipping glaze has a health caution on it, but it is dinnerware safe. In its liquid form, the lead can be harmful, but once it is fired and hardened, it is safe. Exotic glazes should never be used around food because they have a health caution and are not intended for dinnerware use.

Underglaze and Overglaze

Many people find colouring the pottery to be the most exciting part of the hobby. There are two types of glazes used to tint the ceramic. The underglaze is used to create a base coat, or a second colour. Multiple base coats can also be used to make several different shades. The underglaze can then be covered with a clear overglaze or one with additional colour or texture. The overglazes are usually brighter and can be used for full colouring or just accents.

Low-Fire, Mid-Fire, and High-Fire Glaze

The temperature of the heat that the glaze is fired at changes the characteristics of the glaze. Each glaze is made with different materials which react differently to temperatures. The low-fire glazes have to be fired between 883 and 1,120 degrees centigrade and they produce bright colours. Medium-fire glazes go in temperatures between 1,186 and 1,240 degrees centigrade. These have duller colours that are not as pronounced as the lower temperature ones. The high-fire glazes need temperatures between 1,262 and 1,387 centigrade and turn out as either transparent or light colours. In order to achieve a significant amount of colour, multiple coats are needed.

Styles of Ceramic Glazes

Like paints, there are glazes that have different textures and colours. Certain glazes have specific looks that can be used to create a variety of pottery styles.

Styles of Ceramic Glaze

Description

Celadon Pottery

Clear glaze but finishes with a cracked look

Adds texture to the pottery and gives it an aged appearance

The glaze is transparent with different shades

Colors typically white, grey, yellow, blue, and green

Crystalline Glaze

Unique glaze in that its crystals grow and become three dimensional as they cool down

Requires more skill than other types of glaze

Swatow Ware

Swatow ware glazing is an ancient art that came from China around 1500 AD

Usually under fired and comes out blue and white

Shino glaze

Comes from the 1500s and is typically white

Cracks and forms dark sports with streaks when it dries, giving it a unique look

Salt Glaze

Produced by adding salt to the kiln

Results in a high gloss finish with an orange peel texture

However, this method is extremely dangerous because heated sodium chloride emits poisonous fumes

Raku

A method where people remove the pottery from the kiln when it reaches a bright red colour; the the pottery is then placed in a container with materials such as paper that smoke, which causes the glaze to crack and blacken in areas

These are only some of the popular ways to glaze pottery. There are many more ceramic glaze styles that people can choose from.

Find Ceramic Glaze on eBay

Ceramic glazes can only be found at local art shops or online at sites like eBay. Shopping online is usually easiest for art supplies because there is more of a selection. Shops are always limited by how much they can stock on their shelves. On eBay there are thousands of products from different sellers and companies, giving people even more of a variety. They are not limited to looking at just one brand, like they on other websites. To begin browsing, enter the phrase of what you're looking for. For example, type "ceramic glaze", and then click the search button.

Next you can see a list of products available. Be sure to read the product description carefully to determine its safety ratings. It is also a good idea to verify the quality of the product as well as the seller. You can do this by reading through the reviews that other purchasers have posted.

Conclusion

The art of pottery making has been around for centuries and is still being perfected. With it, people have been able to create useful things such as bowls, vases, cups, and plates. Today handcrafted pottery stands out among the masses of machine made pottery as being unique and representative of the artist's talent.

The glaze is the finishing factor of the ceramic pottery and ultimately what determines the overall look. The pottery can turn out shiny, flat, a single colour, two-tones, or textured. Only a basic knowledge of how glazes work is needed to begin a project. For an extra flare, buyers can then choose different styles of glaze that produce a unique effect such as cracking or colour alterations. All that buyers need to remain aware of is the effect they wish to produce, and the importance of knowing what the safety ratings are as well as what temperatures the pottery has to be fired at.

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