Ceramics in itself is a topic with huge breadth and depth so this guide will of necessity only cover the basics as they apply to jewellery components but, I will add a few links at the end for anyone who wants to investigate further.
Types of Clay
There are literally thousands of different types of clay on the market so I am only covering the three basic categories and their distinctions: Earthenware, Stoneware and Porcelain. Different clays 'mature' or become vitreous (will not absorb water) at different temperatures and the higher the firing temperature the more vitreous the end product. Whilst water absorption is not as critical for jewellery components as say an outdoor planter, the level of maturity does have an impact on strength.
When buying ceramic beads you may have come across the terms high fire, mid fire or low fire clay or to cones - a term derived from the pyrometric cones used to monitor the temperature at which kilns fire (see link to video at the end of this post). Commonly used temperature ranges are:
When buying ceramic beads you may have come across the terms high fire, mid fire or low fire clay or to cones - a term derived from the pyrometric cones used to monitor the temperature at which kilns fire (see link to video at the end of this post). Commonly used temperature ranges are:
High Fire – Cone 8 – Cone 10 (2305 F -2381 F or 1263C to 1305C)
Mid Fire – Cone 5 – Cone 6 (2185 F – 2232 F or 1196 C to 1222C)
Low Fire – Cone 06 – Cone 04 (1830 F – 1940 F or 999 C to 1060C)
Low Fire – Cone 06 – Cone 04 (1830 F – 1940 F or 999 C to 1060C)
Porcelain
Porcelain, often considered the hardest clay to work with is a fine grained clay that fires to high temperatures to produce a very strong vitreous ceramic. It is usually pure white in colour and can be translucent when used thinly and is therefore often used for delicate pieces.Stoneware
Stoneware is a coarser grained mid to high firing clay that becomes very durable after firing with little or no water absorption due to the levels of iron and other impurities it can contain.Earthenware
Earthenware is a low firing clay (includes terracotta) and because of this the most porous of the three clay types and therefore the least durable. Earthenware will melt if fired at higher temperatures.Glazes
When it comes to glazing there is also a basic difference between the different types of clay. With mid to high fire clays the glazes fuse more fully to the clay body further increasing its strength. With earthenware the glaze forms a separate layer over the clay which still strengthens the piece but not to the same degree. Because they are highly vitreous, porcelain and stoneware pieces can be used unglazed whereas earthenware is usually glazed (although outside the bead world you will of course have come across unglazed terracotta where the 'breathability' of the clay can be an advantage for items susceptible to cracking in climate changes).
None of this means that earthenware is not suitable for jewellery components - it is and there are many talented designers working with low fire clays. One of the big advantages of low fire clays is that there is a far wider range of glaze colours available particularly in bright and vibrant shades (as you can see below) that don't tolerate high firing. It just means that there are a few extra things to look out for when buying your beads as I will highlight shortly .
Whilst I've used 'glaze' as general term colour and decoration can be added to ceramic beads in many different ways depending on the clay type and firing technique.
To colour these porcelain pods Rey of Grey Bird Studio mixes her own colours and sealants to her own recipes from pigments, oils, waxes and resins - and to great effect.
These pieces use standard mid range stoneware glazes...
And these use standard low fire glazes...
Whilst I've used 'glaze' as general term colour and decoration can be added to ceramic beads in many different ways depending on the clay type and firing technique.
To colour these porcelain pods Rey of Grey Bird Studio mixes her own colours and sealants to her own recipes from pigments, oils, waxes and resins - and to great effect.
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| Porcelain beads by Grey Bird Studio |
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| Stoneware components by Lesley Watt |
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| Earthenware components by Lesley Watt |
Underglazes are pigments that can be used with a clear glaze or unglazed as here...
This lovely piece by Jenny uses Oxide stains and underglaze on porcelain for a more earthy effect.
What to look out for when buying beads
Whatever type of clay the beads you are considering buying are made from there are some basic things to look out for but I would like to add a caveat here... I am talking about handmade artisan beads so I am in no way suggesting that beads have to have precise uniformity and no imperfections - that would just stifle creativity and miss the point completely.
The aim is simply to point out some areas to look out for to make sure you're getting value for money.
The aim is simply to point out some areas to look out for to make sure you're getting value for money.
Strength and purpose
The first thing to remember when buying ceramic beads is that however strong they are they are not indestructible. I've dropped plenty of stoneware beads and had them bounce but I've also had them land on ceramic tiles or granite and break or chip. Porcelain is tough but if your piece is delicate it's not going to withstand rough handling. As a rule if you treat your ceramic beads as would lampwork beads you should be ok.
As the less durable of the clays I would add a couple of caveats when buying earthenware pieces...this is what happens when you drop one getting it out of the kiln...poor puss!
Very thin pieces may not be that strong as you can see from this early bracelet bar of Caroline's which she managed to snap just with her fingers. At 3mm this was a bit too thin, especially for a bracelet bar which is likely to get knocked about about during wear. Pendants don't get so much wear and tear so perhaps don't have to be quite so robust.
If you're planning to use your purchase with jump rings or wire, make sure the holes are big enough and not too close to the edge of the piece. Wire wrapping or opening and closing too tight jump rings will put the piece under pressure and beware those pliers!
Bead holes
Bead holes
Bead holes should always be clean and smooth with no rough edges, no blockages in the holes and no chips to the glaze. The last thing you want is to make a piece of jewellery only to have the beads slice through your stringing medium!
Good holes...
Not so good holes... here you can see bits of clay stuck in and around the holes and chipped edges.
Caroline very kindly supplied these images of some of her bead 'fails'.. and we all have them. Here the glaze has run into the holes and stuck to the wires during firing causing sharp edges and an imperfect appearance.
Another thing to look out for around bead holes is cracking... here are some of my stoneware beads that were fine after the first bisque firing (lower temperature) but when fired to maturity cracks appeared.
The positioning of the holes is also worth taking note of too as badly placed holes can have an impact on how you design with your beads. I made these lentils by joining two halves together but when I put the holes through I missed the centre which means the beads will be heavier on one side and may not hang well.
Wire Attachements
High Fire wire (Kanthal/NiChrome) is often used in component design and again there are a couple of things worth checking. First up make sure that the wire is substantial enough to support the piece and the plans you have for it. Although it is designed to be fired at high temperatures the wire does weaken somewhat during the firing process and if the gauge is too thin it may buckle or break further down the line.
Wire can also cause cracking in the clay as I found to my cost with these poor bunnies and whilst the wires are still firmly in place I would not sell them in this condition.
Here the wire shank on a button has been pushed too far in and is protruding sharply through the front of the button - not good.
Warping
Warping is a common problem particularly at higher temperatures and with thinner pieces. This is not necessarily an issue if you're looking for an organic design or not too worried about it being flat - then a little warpage can add character. If you're looking for a cabochon to fit in a precise setting that requires a flat back though, it may cause you problems so it pays to think ahead a little.
Warping is a common problem particularly at higher temperatures and with thinner pieces. This is not necessarily an issue if you're looking for an organic design or not too worried about it being flat - then a little warpage can add character. If you're looking for a cabochon to fit in a precise setting that requires a flat back though, it may cause you problems so it pays to think ahead a little.
Rustic style
Rustic or free form designs are growing in popularity and well made they have a wonderful aesthetic appeal but rustic is not an interchangeable descriptor with rough. Artists making this style of component will go to great lengths to ensure that any organic or unfinished detail is safe to the wearers skin and their clothes by smoothing away any sharp edges that can catch. This piece by Jenny is a good example...
Glaze faults
One of the most exciting thing about working with glazes is that you're never quite sure what alchemy is going on in your kiln and what you're going to get when you open it. Glazes often do things you don't expect and things can happen that theoretically are flaws. Sometimes these flaws become a happy accident that creates a whole new look but sometimes they're just flaws and should be consigned to the reject bucket...
Tiny pin holes in a glaze can sometimes create a nice textural effect but not when they look like the ones I got here which are likely to chip and could snag on clothes and skin.
Glaze application should generally be smooth and even unless there is an intentional design element at play and sadly this little fellow has a nasty case of blotchy glaze that has been applied too thinly in parts.
So there are just a few things to look out for when you are buying ceramic art beads and I hope you've found it useful. As I mentioned before we are talking about handmade beads and the very fact that they are all unique is their charm. Good designers will always be aware of the limitations of their mediums and create accordingly with love and attention to detail because they want you to be as happy with your purchases as they are making them.
Of course, it can be difficult to pick up these points when you're buying online but good clear listing photographs should make any issues apparent (personally I do not buy from poorly photographed listings) and if for any reason you're not happy with your purchase contact the seller as soon as you can to discuss.
If you're new to ceramic art beads and want to see more pop along to the Facebook auction group Ceramic Art Bead Market.
Glossary of ceramic terms
