Top ten tips on pottery firing

Pottery making provides some challenges for the beginner but non more so than at the firing stage. No-one wants to lose their precious ware after making it so lovingly. It is quite usual for small studio and craft potters to use intermittent box type kilns to fire their ware. Whether you use gas or electric as the energy source the principle is the same; heating an enclosed space containing shelves of pottery. Whilst the science of firing is quite complex and often outside the knowledge of many hobby potters most know it is important to follow some basic rules. The following tips are aimed at giving you the best performance from your kiln whatever the type.

1. Temperature uniformity is key to achieving consistent results. This should be the aim when firing your kiln.
2. Measure the performance of your kiln using bullers rings or Orton cones. Control it using an electronic temperature controller.
3. Record firing cycles used and settings for each firing as well as Bullers Ring or Orton Cone values.
4. Measure and record the gas or electricity used in KWH for each firing. The trends in this often give you a pre-warning of catastrophic failure.
5. Regularly calibrate thermocouples as they deteriorate over time.
6. Inspect refractory brick or lining regularly to ensure large cracks are not present. Remember large cracks in brickwork will affect kiln temperature uniformity.
7. Inspect electric elements regularly as over time they become brittle and may distort or break.
8. For gas users the colour of the flame is a guide to the kiln atmosphere. Yellow flame is reducing while blue flame is oxidising.
9. Placing ware affects the firing performance of the kiln. Large or thick walled pieces require more heat and act as a heat sink.
10. Don't be greedy- firing pottery too fast can lead to all manner of faults. Unless the glaze and body are designed to be fast fired don't do it!

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend.

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Should I make my own Pottery Glazes?

Coloured glazes used by Tinkling toadstools

This question has caused a lot of debate among potters. It is a similar question to "should I make my own bread, cakes or pastry?" Clearly there is no right and wrong answer. People who bake their own bread and cakes do so for numerous reasons. Whether it is to reduce costs or make it fresh or make it taste better; all are valid reasons. However most do it because they like it and the self satisfaction it gives them to create something of value.

 Similarly, the potter will often claim that making glazes gives him the same type of satisfaction, is cheaper and gives him more scope for creativity! But lets look at the issues involved in making glazes in detail to see if his claims are true:-

 Costs

Glaze materials

There is little debate that buying the glaze materials to make the glaze can reduce costs significantly. Common materials such as clays, felspars, silica, frits and pigments are all readily available from a number of suppliers. However, often they are not in the ideal form to produce a glaze without additional processing. Most need at least a number of processing steps to make a satisfactory glaze. These steps include, preparing a recipe, grinding or mixing with water, sieving, magneting, testing, and controlling the glaze slip consistency using additives. The time and knowledge to correctly process and test the glaze are mostly overlooked when cost comparisons are made. For those with time to learn about glaze materials and the process this is not an issue. However for many hobbyists who are time poor it clearly does not make sense economically.They are better using reliable commercial glazes.

Creativity

Unique copper ruby glaze

Without doubt making your own glazes is a creative exercise. Again using the same cake making analogy as before, you have complete control of the make up of the glaze and how it will look after firing. Just like cake recipes there are thousands of recipes for glazes each giving its unique colour, texture and appearance depending on how its fired. This uniqueness is what many studio potters strive for.  By varying the pigments and make up of the glaze in theory you can innovate to your hearts desire! Therefore creativity can surely be improved by making your own glazes!

Technical restrictions

In practice, however,  there is considerable science behind making acceptable glazes:

• The glaze needs to technically match the body or the glaze may just peel off like old paint. 

• There is a limit to the range of compositions that can be made- for example some recipes will just never make glossy glazes.
  
• The firing cycle and atmosphere have as great an affect on the glaze appearance as the recipe.

The fired glaze surface of functional tableware needs to pass the requirements of legislation e.g. toxic metal release into foodstuffs.

So if you want to be creative with glazes you also need to have some technical knowledge. Potters without a scientific background may struggle to understand these technical parameters and hence making glazes could ultimately become more trouble than its worth.

Health and Safety

Unleaded Glaze

In recent years this issue has grown in importance for potters making their own glazes. Lead, for example, is being phased out in commercial glazes and its use and safety has been severely questioned especially in the USA. Other materials such as Barium compounds need to be used within strict guidelines for safe use. Even pigments such as cobalt and nickel oxide have been questioned over their safety. Clearly there is a lot to learn technically to comply with health and safety during the making of glazes. These issues are understood by commercial glaze manufacturers who can provide up to date data sheets on the glazes they manufacture and supply.

Equally important is an understanding of the legislation that applies to the fired product to meet the demands of the end market. Functional tableware has to meet much more legislation than ornamental ware in the various countries around the world.

Summary

In summary making your own glazes safely and successfully is much more difficult than at first appreciated. Technical and health and safety issues are not easy to overcome. However for a potter or hobbyist with a scientific understanding he can indeed be more creative and lower some material costs by making his own glazes. For the uninitiated it will be a long road of trial and error and frustrations. For those determined to try I recommend you do some reading and preparation online or in the wealth of books available before you begin. 

Good Luck and Happy Potting

The Potters Friend

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend.

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Inspirational pottery glazes

The special ceramic materials and process

Reactive coloured glazes

The first article of my series on glaze making identified the basic ingredients used in glazes as silica, felspar, frit, and clay and explained how a little science would help speed up your artistic flair!.This second of the series on glaze making discusses the non core ingredients of a glaze and explains how a little science in the form of good processing can ensure that you achieve the best result from your glaze making efforts.

The 3 Basic Questions

To make truly inspirational glazes we need to establish at least 3 things

1) What type of glaze we want to make?

2) What type of body it will be applied to? Stoneware?, Earthenware? Biscuit? Clay?

3) What firing temperature/cycle do we intend to use?

Once we have the answers to these questions we can begin to formulate the glaze.

The choice of non core glaze materials

Making a silky matt -what to add to your basic glaze

Silky Matt glaze

Let us assume we want to make a white silky matt textured glaze firing at 1150C on stoneware biscuit.

We have already identified silica, felspar, clay and frit as core glaze materials. This means that at least 2 of these materials are used in almost all glazes.

Using the same cake making analogy as before, these ingredients are considered the eggs, butter, flour and sugar equivalents of the glaze recipe!

The materials we might consider adding to these core materials could be:-

Limestone (calcium carbonate)

Needle-like crystals on glaze surface

Dolomite (calcium magnesium carbonate)

Zinc oxide

Alumina (aluminium oxide)

wollastonite (calcium silicate)

clay (alumino silicate)

These materials help to form crystals on the surface of the glaze on firing and thereby help create the matt (dull) texture. However these materials also influence how the glaze melts and bonds to the body on firing. It is an absolute necessity to match the glaze to the clay body or on cooling the glaze may just flake way like old paint! (Technically the glaze and body thermal expansion need to match so that the glaze is in compression after firing.) But lets not go too deeply into how we do that at this stage.

Alumina does not readily melt at this temperature so the likely (and easier) materials to use are zinc oxide, limestone, dolomite and wollastonite. Adding these materials in the right proportions to make a suitable glaze takes a lot of trial and error.

Developing the Glaze Recipe

If you start a with a basic 1250 C recipe as follows:

Base Glaze

Silica 38

Felspar 40

Clay 10

Limestone 12

and start replacing the silica and felspar with more fluxing ingredients that create crystals and allow you to fire at a lower temperature you might eventually reach a formula

Modified Glaze

Limestone 12

Dolomite 25

Felspar 20

Clay 25

Zinc oxide 4

Boron frit 9

Silica 5

Imagine how many test glazes you might need to make before arriving at such a detailed recipe? Note how different this is from the starting base transparent glaze! The material recipe is not the only part to consider when making glaze. The particle size of the glaze materials needs to be reduced to a fine powder by grinding with ceramic pebbles in water to less than 75 microns. Often, for best results, the mean particle size needs to be closer to 15 microns-the diameter of the finest human hair. This allows the glaze particles to react and melt during the firing process.

Firing the Glaze

The firing process is equally important in obtaining satisfactory and repeatable glaze results. Initially the firing cycle should remain constant as you develop your glaze recipe. A typical glaze cycle might be 150 C per hour ramp from room temperature to the peak at 1150 C, followed by a holding period (soak) at peak temperature of 1 hour, followed by kiln switch off and natural cool to room temperature.

Note that the cooling is often as important as the heating process when firing matt or crystal type glazes.

Clearly making glazes is quite a complex process. However, like the best potters, in time you will come to believe that this is what makes pottery glazing so interesting. You can never be sure what will come out of the kiln each day!

In the next of the series the use of ceramic colouring pigments to create even more interesting coloured pieces will be examined..

Pottery books of value

A great way of backing up your knowledge is to read some simple pottery making books. Some of the best books are those you keep going back to as your knowledge grows!

Thought for the Day

In pottery making it rarely goes exactly as you would like first time. Stay positive! Use it as a learning experience.

Henry Ford Quote:

"Failure is only the opportunity to begin again, only this time more wisely."

~ Henry Ford

Happy Potting
The potters Friend

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend. Go now to sign up for my free newsletter.

Opacification of Glazes

Glaze opacifiers are materials which when added to a glaze change the level of transparency of the glaze. Glazes are often described as clear/transparent or opaque. In order to achieve color tone and hide the body color it is often necessary to add opacifier particles which stay discrete in the glaze after firing. Materials which have a significant difference in refractive index from the parent glaze produce the most effective opacification. To the right you can see the effect of adding an opacifier to a transparent glaze. It becomes whiter and milky (opacified ) in nature and flows less.

Below you can see the effect of adding opacifier to a transparent glaze containing different colored pigments

Top = transparent glaze            Bottom = opaque glaze

Typical glaze opacifiers are zircon (zirconium silicate), tin oxide, and titania (titanium dioxide). 

Zircon opacifier powder

Zircon

Zircon is the preferred opacifier for glaze due to the low cost, inertness and stability in glaze. To achieve full opacification, the opacifier content and the particle size are important factors. For addition of zircon to the glaze mill during grinding a particle size of 95% less than 3 microns and a content of 5-10% ensures sufficient opacifier is dispersed to create optimum opacity.  

However an exceptional level of opacity can be achieved by pre-melting the zircon into a glass (called frit) and then using the frit as part of the glaze recipe. These frits are transparent before firing but crystallize zircon during the glaze firing process to give a high level of opacity. 

Tin Oxide

Tin oxide has historically been used as a glaze opacifier but its high cost has limited its recent use to low temperature majolica or special effect glazes. At a level of 5% in a transparent glaze a high level of opacity can be achieved. Its lower solubility in glaze compared to zircon means that lower levels of tin oxide can be used to create the same level of opacity as zircon.. Tin gives a slightly blue white tinge and also has a lesser effect on the glaze appearance than zircon which increases glaze viscosity during dissolution.One major drawback of tin is it reactivity with some oxide pigments. For example, with chrome oxide a pink discoloration may result from the formation of a chrome-tin spinel crystal.

Titania reactive glazes

Titania

Titania is also a very costly opacifier and is used primarily where reactive special effect glazes are required. Like zircon it has a higher solubility than tin in the glaze and even at levels of 4%  tends to give a yellow tinge to the glaze after firing. It readily reacts with other materials in the glaze to create many unusual crystalline phases on cooling.This is ideal for special effect glazes but undesirable for standard opaque glazes.

Happy Potting

The Potters Friend

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend.

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The Wedgwood Collection and the changing face of UK pottery

Wedgwood Museum

Staffordshire pottery manufacture changed forever in the late 1980's and early 1990's. The power of the supermarket buyers, the draw of low cost manufacture overseas and the changing markets in Europe all contributed to the massive decline in pottery manufacture in the UK. So many big names like Royal Doulton, Spode, and Royal Worcester, to name but a few, now exist merely as brands with the factories closed and demolished. Bleak as it was for the thousands of workers who lost their jobs during that time, many of those workers still talk fondly of the friendships, skills and pride of working in the hundreds of potbanks which existed at that time in north Staffordshire and especially Stoke on Trent.

Staffordshire Oatcakes

It was not just  the potteries that demised but also the services to those factories, the engineers, the material suppliers and sandwich and oatcake shops that provided breakfast and lunch to the hungry workers at break times.For the lucky few they found work elsewhere and the humble Staffordshire Oatcake lives on mainly through online marketing and Social Media.

Many of those pottery workers now rely heavily on their work pensions created during their employment at companies like Wedgwood. However Wedgwood pension trust has a big pension deficit that is causing  problems.

Over the last few years the importance of this pension deficit has been highlighted as the struggle to keep the magnificent Wedgwood Collection at its home in the Wedgwood museum in Stoke on Trent continues.

For those who have not seen the collection I urge you to do so. You will not be disappointed. At over 80,000 historical pieces, ranging from early experiments for new bodies and glazes through to modern production as well as rare manuscripts and letters, pattern books, works of art and photographs, covering the 250-year Wedgwood history, it is one of the most unique industrial archives in the world. The importance of the collection is explained in more detail in this Wedgwood video link.

The collection is under threat because a legal loophole allowed a Wedgwood previously in liquidation to place pension debt in the Museum trust. The trustees have no option but to try to pay off this debt by selling some or all of the collection.

We cannot lose this collection from the UK or allow it to be dispersed around the world to private collectors. It is OUR heritage and I urge you to donate to help meet the £2.74m shortfall still required to keep the collection together in the UK.

Thank you for your support.

Pottery Materials-Potters You've Never Had it So Good!

Sources of materials

Materials dug from the ground have been the source of pottery making for thousands of years. However early potters relied heavily on local materials, especially the clays and sands. This was certainly the case in my beloved Staffordshire, England where local marl clays formed the major source of clay for early industrial potters.

Borax granules

Today materials are shipped around the world to areas of high industrial scale ceramic manufacture. For example the high quality white china clays from the south of England are often shipped to Asia to make the finest bone china and porcelain bodies. Similarly borax and boron minerals from Turkey and the USA are used in Europe to make glazes and frits for tile, tableware and sanitary ware manufacture.

However it is not just the source of available materials but also the quality and consistency that has helped modern potters and potteries to improve their quality, designs and efficiency.

Materials for body making

Body materials

The main materials used to produce a clay body are silica or quartz, felspar, and clays. These materials come in various purities, particle sizes, and qualities. To produce the finest white bodies, high purity low iron materials are used and these materials are sourced locally where available. However most areas of pottery manufacture do not have the required purity or consistency required from all their local suppliers and are therefore forced to consider other supplies. It is the consistency in purity, and control of of material properties that has made a significant difference to large scale pottery manufacturers. They can automate processes and improve efficiency to reduce costs. Materials are now stardardised to fit processing routes. For example 30 mesh and 200 mesh materials are common in the UK. These improvements in materials for industrial scale customers also has a knock on benefit for craft, hobby and studio potters who can also purchase these same materials from distributors and use them with greater confidence.

Materials for glaze making

Frit granules

Like body the main materials used for glaze making are silica, china clay, and felspar. However frits (fused glass fragments) and other minerals such as limestone, dolomite, wollastonite, zircon are often added to control the fired properties of the glaze. Expensive technical grade chemicals such as zinc oxide, barium carbonate,and boric acid are also used in small quantities in the glaze or frit to meet the most demanding glaze requirements. However it is in the use of boron products where industrial scale and craft scale differ the most. Large scale glaze manufacturers predominantly use frits as a source of boron, where craft glaze makers use boron products such as Gerstley borate. The benefits of using frits for industrial scale glaze manufacture are far reaching. The recipe of the glaze is designed to be lead free and often fine tuned to give the widest firing range and technical performance. Control of glaze slip properties, glaze application, and firing properties are of paramount importance especially in automated plants which are not suited to the use of borates in glaze. Slip control of the glaze involves controlling both the solids content of the slurry, the viscosity (fluidity) and the drying time by means of chemical additives.

This differentiation in supply is a benefit to craft and hobby potters who can choose a from a wide range of frits or borates depending on their scale of operation or cost needs. .

Materials for decoration

A whole range of  methods are now available for decoration of pottery. When colour was introduced to pottery in early years it was in the form of naturally occurring coloured minerals usually high in iron. Consequently the colour range was restricted to brown- red to grey blue in colour depending on the firing condition. However with the development of pigments from the eighteenth century many more colours became available with Chinese blue colour on white glaze becoming very popular.                                      

range of onglaze decorating colours

Today a full range of stable mixable ceramic colours are available ranging from bright yellow to blue to red. Together with a wider range of decorating techniques the modern potter now has the opportunity to design truly unique ware that is also repeatable.

Range of ceramic stains

To put this into perspective an anology might be to compare Fords "you can have it in any colour as long as its black" to the current range of colours and effects used to paint modern vehicles.

In a similar way to body and glaze materials, decorating colours such as onglaze have become standardised and more consistent in both their application and firing. Colours have been developed without lead and are available in the best medium (liquid) to allow optimum application whether that is hand painting, machine banding or screen printing. Introduction of digital printing has allowed digital images to be translated from computer to ware using ink jet decals or even direct printing in a similar fashion to paper printing. For the hand made purists in pottery computer support to design has not always been welcomed but it has extended the range of design to new levels.

In the future design will be pushed even further by 3D printing which is in its infancy in the pottery industry.

Summary

Clearly material technology and control in the pottery industry has progressed almost unnoticed since the early eighteenth century pottery manufacture. However it has progressed and the development of more consistent, environmentally friendly colours together with a wider colour palette has been of great benefit to modern potters, large and small..  The advent of digital printing in recent years and the potential of 3D printing is set to revolutionise the industry further creating even more design possibilities.

Yes Potters it is true! You've never had it so good!

Comments welcomed?

Happy Potting

The Potters Friend

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend.

Go now to sign up for my free newsletter.

How to Make Coloured Pottery

The Appeal of Colour

Copper Ruby glaze

The addition of colour to pottery adds so much to its appeal. Whilst white pottery can emphasise the distinctive form of a piece it is often colour which catches the eye! Colour is often associated with a mood or feeling and this varies between cultures and countries. For example red is a very emotive colour and can mean anything from love and romance to danger and fire! Choosing the right colour to make or decorate your pottery however is a matter of personal choice and allows for much creativity and freedom of expression.

Colour can be added to pottery in many ways including body colour, underglaze, inglaze, onglaze and also as a component of the glaze itself.

In this article I will try to review the two main types of ceramic pigment ( raw oxide and ceramic stains) available and how they can be used to produce highly decorative pottery.

In the second of my series on glaze I described how to make a white textured stoneware glaze. 
Simply adding inorganic colouring oxides such as Iron Oxide to such a glaze produces colour but not always the desired colour!  Carry on reading to find out why!

Raw Oxides in Coloured Glaze

Top = Oxides in transparent glaze
Bottom = Oxides in opaque glaze

Copper oxide crackle glaze

It is common for raw oxide pigments to be used used in pottery making. Many studio and craft potters prefer to use cobalt oxide, chrome oxide, Iron oxide and copper oxide as colouring pigments.These oxides give blue, green, yellow-brown, and green-blue respectively on firing in or under the glaze. Often the fired colour of the starting oxide is not the same as the original oxide colour e.g. cobalt oxide changes from black to blue on firing in a glaze. However mixing of these oxides in a glaze, gives variable but often aesthetically pleasing artistic effects on firing. It is for this reason, and the lower cost involved that many studio potters often use these materials.

Iron Oxide and cobalt oxide in glazes

In using oxides as pigments It is important to match the pigment type and content to the glaze to achieve the most consistent results. In the example above iron oxide gives a yellow colour when added to a glaze in small percentage (eg 1%) compared to a brown colour in high percentage (eg 15%). In combination iron oxide and cobalt oxide often give grey or a black glaze colour (see example right). The difference in the colour between an opaque and transparent glaze containing the same pigment content is also marked. In the example above the same pigment content is compared in a transparent glaze (top) and an opaque glaze (bottom). A stoneware textured glaze will produce colour tones similar to those of an opaque glaze.


Organic pigments such as those used in paper printing are clearly not suitable and will simply burn away during firing

Ceramic Stains in Coloured Glazes

Top = Ceramic stains in transparent glaze
Bottom = Ceramic stains in opaque glaze

In contrast to raw oxide pigments, ceramic stains have been specially formulated to create a wide range of colour tones in glaze. In their manufacture they have undergone a heat process and a fine grinding process so that they are highly temperature stable and capable of being mixed together to generate intermediate colour tones. This property is highly valued by large scale manufacturers who need consistency of colour tones. However this all comes at a cost compared to raw oxides.

Onglaze and Inglaze Decoration

Pantone Mugs showing onglaze colours

It is common for high quality whitewares such as bone china and porcelain to be decorated with special colours called onglaze (low temperature) or inglaze (high temperature). These colours use a mix of special fluxes and the ceramic stains identified above to create a wide range of intense, durable colours and bond them to the already fired glaze surface.. Whilst a few studio potters try to make their own, they are best supplied by specialist manufacturers to ensure they meet current legislation and perform satisfactorily in use. These colours are often supplied as powders or pre-dispersed in a liquid allowing them to be applied by hand painting or screen printing. This type of colour is very versatile and is often used to make precision decorative decals for water slide application onto pre-glazed pottery. A new development called Digital printing now allows these decals to be personalised and produced in small quantities making it a cost effective method of decoration for craft and hobby use.

Summary

Clearly there is more to making coloured pottery than is immediately obvious. For those who want consistent colour that can be mixed to give intermediate shades then use ceramic stains either as a glaze component or in decoration products such as inglaze or onglaze colours. For those who want unpredictable but aesthetically pleasing results use oxides as a glaze component or under the glaze. Whichever option you choose using colour creatively will only add to the appeal of your pottery.

Happy Potting
The Potters Friend

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend.

Go now to sign up for my free newsletter.

Self cleaning plates and lego style brick houses? Are these ceramics of the future?

Legoland By Copyright © 2003 Kaihsu Tai
via Wikimedia Commons

Self cleaning Glass

I recently read an article about the possible future of textiles. Designers were predicting the living shoe and the strawberry plant that grows lace. Whilst fanciful such ideas have a slim chance of becoming reality.

That made me think about ceramics. What will be the future of our beloved ceramics in 50 years from now? Perhaps it will be self cleaning plates and lego style brick houses? Again these may seem far fetched to most but they are already possible in a small way.

The next 50 years in ceramics - my vision

My vision  is based mostly on what is possible now but not necessarily in ceramics

100% Recycling

Without doubt ceramics will be recycled in a more comprehensive and systematic way. Recycling points will be readily available in every part of the country. Ceramics will be reprocessed by barcode or other tracer systems which will allow them to be separated  for more economic recycling or re-use.

Greater personalisation in Design

The changes in pottery fashion are more rapid now than at any other time. This trend is likely to continue. Changes to our dining habits, less formal dining and more casual dining, is reflected in the ceramics we buy. Ceramics are now mostly considered a disposable item and need to fit more closely with our lifestyles. This has led to a wider choice of colour and shape. For example a whole range of ware may be used for dining instead of a single dinner plate.

The future however is likely to bring us even more personalisation in design. Designs will be agreed at the point of sale or online and products will leave the factory 24 hours later. Scope for designing your own tableware is not far away now and will be common place in the future. Personalisation is already available in a small way but this will grow exponentially as technology progresses.

Lightweight strong ceramics

Abalone Armor Paper-thin armor courtesy of nature Andreas Walther

Ceramics will become lighter and stronger! Lightweight ceramics have already been developed for military purposes but ultimately these ceramics will become part of the pottery scene. The advantages of light weight and strength are significant not only to the carbon footprint but also to manufacturing and transport costs.

Egg shell porcelain courtesy
of Victoria and Albert museum

 A good example of ultra thin ceramics is Eggshell porcelain , a delicate porcelain often decorated with a watermark-like image dating back to the Ming dynasty (1402-1424). Nevertheless because of lack of strength it has not found widespread use for dinnerware. Future ultra thin ceramics will have sufficient strength to make them suitable for a wide range of ceramics.

Imagine drinking from a paper thin highly decorated mug that is  heat retaining but virtually unbreakable?

Warm self cleaning sanitaryware

Composite materials are mixtures of materials eg ceramic and plastic which when combined give superior properties when compared to the individual materials alone. Such type of materials are common place in the military and aerospace industry. However they are less well used in domestic applications. Nevertheless car windshields are often a composite of glass and plastic. Here a layer of plastic is embedded in between two layers of glass to give extra strength and toughness.

In time other composite materials will emerge in household products. I can imagine a bathroom where the ceramic composites used are warm to the touch, with antibacteral surfaces that are virtually self cleaning. Water is recycled at point of use via ceramic composite filtering systems.

3D Digital printing- or how to doodle your own cup and plate!

2d digital printing of colour

3d digital printing of a sugar bowl

Digital 2d colour printing is already well established for printing of coloured images on to paper. It is already making significant inroads for the decoration of tiles and tableware. In the case of ceramics the 4 colours used in ink jet photocopier type machines are replaced by up to 10 ceramic coloured inks. These are then used to decorate ceramics directly or via an intermediate stage such as paper transfers. The result is a high quality image in rapid time using an amazingly flexible system. But digital printing does not stop there! 3D printing of ceramics is in its infancy. Greater design possibilities as well as the personalisation already discussed above will become the norm.

 But what does this all mean? In essence a 3d computer design will create a 3 dimensional object via a robotic system by building a series of 2d layers. A good analogy would be building a wall brick by brick but at particle or even molecualar level.

 Already there is a 3d printing pen that transfers what you draw into a 3d object in plastic. If you had a pen that would allow you to doodle a 3d object of the future what would  you draw?

Eco Style Ceramic bricks and panels

Eco house from

Although the detail of design, decoration and processes used in brick making has changed greatly in recent years, the basic idea of shaping raw clay into rectangular blocks remains much the same. Ceramic bricks have changed little in hundreds of years. In many ways this is cost driven so will need radical changes in house construction for this concept to change. 

However this is happening albeit slowly as more eco houses are being constructed (in part) off site and delivered to site for final assembly. This trend will continue. The idea of coventional bricks will change as this type of housing grows. It is not too stretching an idea to believe that strong lightweight ceramics in the form of legotype bricks or panels could be used in all future house construction. 

Who knows the eco house of the future could be manufactured entirely off site and only services and fixings completed on site! 

What do you think?

So whilst far fetched I believe many of the above have a reasonable chance of becoming reality. What do you think of my ideas? Do you have some (better) ideas of your own? I look forward to hearing all about them.

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend.

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Digital printing of ceramics

Digital printing of ceramics and decals

Digital printing of decals and ceramic tiles is already well established. Computer generated images can be printed directly onto ceramic tiles via special inkjet systems. Alternatively a photocopier type system can be used to print onto decal paper. Of course both these systems require special machines and ceramic inks or toners to produce optimum results. Nevertheless these systems are causing a revolution in the ceramic tile industry.

The detail of decal printing

Ricoh desktop ceramic printer

In the case of digital decal, you can either create a drawing or photograph and then convert it to a digital image suitable for printing on to decal paper. The image is produced as a decal by a photocopier type machine. After printing the image is sealed to the paper with a covercoat and allowed to dry. The decal can then be applied in the same way as conventional decals by a water slide method. Decorators have the choice of either outsourcing decals (small quantities) or for large quantities buying a machine and toners and printing themselves..

The detail of ink jet printing of tiles

Pigment	System	Temperature	Colour
Yellow	Zr-Si- Pr	1250 °C
Red Magenta	Zr-Cd-Si-Se	1250 °C
Cyan	Zr-V-Si	1250 °C
Black	Fe-Cr-Co-Ni	1250 °C
Primary 4 colours used in ink jet printing

In the case of ink jet printing, the digital image is converted to a ceramic image using a specially adapted ink jet printer and special inks. The ceramic tile passes beneath the printer head and the ink jet colour nozzles deposit the image on the tile.

Gamma Ink Jet Tile Printer

Typically up to 10 ceramic colours are used to produce high quality digital images, 4 similar to the primary colours shown above plus additional spot colours. Browns, coral reds and white are commonly used to fill gaps in the colour space. Special printer heads are used to cope with the highly abrasive ceramic inks. For maximum definition and colour intensity special glazes are sometimes used as the base for printing the coloured image. The printed item can be fired almost immediately after drying.

3d Printing of Ceramics

I am constantly amazed at the ceramic challenges I see each year. Whilst making pottery and ceramics is an ancient tradition, new industrial processes and products (or the re-introduction of many older techniques) continue to stretch the imagination.

3d printed sugar bowl

Both in the UK and USA, 3 dimensional digital printing is one such technique. Developed initially for rapid prototyping of plastic objects it is now being used for small special ceramic parts. The potential to build up a ceramic mug  layer by layer  from a computer image is certainly feasible.
 I have seen the initial prototypes which have been glazed and fired. Many technical challenges remain for this process to be viable commercially but I have no doubt that in the long term this will happen.
For more information about this technique see the link project below:-
 University of Bristol project

3d printing using liquid clay syringe

3d extruder printing

This type of printing is also in the early stages of development for ceramics. Many questions remain particularly control of rheology and removing air pockets and machine development.. However the picture on the right shows how the process works. An air powered syringe forces liquid clay out of the nozzle to build up the object in layers. The head could be computer controlled to map out a digital design.
Potentially the ceramic designer can be creative in designing complex forms as well as simple shapes.
Picture and link to more information kindly provided by Ceramic 3D Extruder (FabLabZuidLimburg) / CC BY-NC 3.0

So what does this mean to the hobby or studio potter?

The opportunity to make low cost efficient designs which can be personalised to meet your customer needs. Digital ceramic decals are already established and widely available. But keep following the progress of 3d printing as the potential is endless. Perhaps now is the time to look at ways these techniques can expand your opportunities?

More information and other technical articles on pottery and ceramics can be found at my website The Potters Friend. Go now to sign up for my free newsletter.