Sourcing Clay // how and why

When it comes to choosing the clay I work with, there are a few factors I consider and a wide range to select from. I could dig up clays and really take it back to basics, however this is not really suitable for everyday use so it doesn’t inspire me as I want to make things people can use for a lifetime. This choice is individual to the potter and the intended function of the pottery being made...wild sourced clay is amazing and if it tickles your fancy then I say get out there and dig!

When I am sourcing bags of clay from a manufacturer or a ceramics suppler, the first thing I do is research the company and the clays they have on offer. There are questions I endeavor to answer that reveal whether the clays and/or the company are a sustainable choice for my work.

The 3 questions I feel are most important are:

What are the raw ingredients?

Where are they coming from?

How are the produced?

I know from asking and digging that little bit deeper that the main clay I use is made up of a blend of fireclays and marls from South Staffordshire and Shropshire, ball and china clays from Devon & Cornwall, and sand from Cheshire.

I also know that it is a panmilled body which requires skill and experience from the operative. The raw materials are blended in specially adapted panmills, which were once used for blending chocolate at Cadbury’s in a former life.

Knowing where my ingredients are mined and produced is always at the top of my ‘must know’ list and allows me to work out the most sustainable option for me. As I live in the UK I favor ingredients that have not been imported from faraway lands, firstly because of the carbon footprint but also due to the ethical standards of mining.

Basically to import raw materials from abroad is cheaper than to mine it within the UK however the standards in particular countries cause harm to people, animals and the environment. Read my glaze making post for more about that. Unfortunately where the ingredients have been mined is not printed on the packaging. I have to ask the supplier and not all of them are happy to give over this information.

The clay I predominantly use and will use as an example here, contents Ball and China Clay from Devon & Cornwall. Most clays will have Ball and China Clay in its mixture and you can also buy it in raw form if you want to make own clays or glazes.

Both China Clay and Ball Clay are also mined internationally. I have also learnt how to identify where ingredients are mined through continued research and questions. You see if you want to buy raw China clay or Ball clay there will be many available types to pick from however where they are mined its not often stated in black and white but the labelling they use is translatable if you know what your looking for.

For example I now know that EPK China Clay is mined in Florida whereas Grolleg China Clay is mined in Cornwall and Hymod Ball Clay is mined in Dorset or Hyplas Ball Clay is mined in Devon. It really is a MINED_FIELD !

Imerys : St Austell, dry mining plant in Cornwall.

I guess what I am trying to demonstrate is that making sustainable choices as a potter requires a fair amount of knowledge and effort even when simply just sourcing a bag of clay.

Even if I were lucky enough to have a cute ceramic supply shop, in walking distance from my studio, sadly that doesn’t make it the most sustainable choice for me. Yes my own carbon footprint to and from the shop would be great but the clay could quite possibly be imported and I would still need to ensure is it has sourced responsibly.

As an individual maker, its important to me that any pre-made clays I use have been fully researched and come from a trusted source.

I do this because I don’t want it to have a massive carbon footprint or for my main material to be full of ingredients that were mined un-sustainably, disregarding human rights, or poorly affecting global greenhouse gas emissions. So I ask questions to anyone willing to answer them, which can sometimes annoy suppliers but I do it anyway.

Doing your own research

If your a potter and your thinking about approaching your clay supplier to ask a few of your own questions then its useful to understand the difference between a manufacturer and a supplier.

A manufacturer is a company that will produce the clay on site, sell it directly from their own website/ shop and supply their pre-made clay bodies to other suppliers. They may also supply other manufacturer’s products on their website/ shop, which can of course be a little confusing.

A supplier is a company that imports and distributes pre-made clay bodies from a number of manufacturers from their a warehouse or shop directly. Therefore to get technical information about clay it is best to ask the manufacturers themselves as most suppliers will only have basic information.

To begin your research, explore the websites of the suppliers and manufacturers you are considering buying clay from. You will be able to find information about how long they have been in business, if they are family run and whether they distribute throughout the UK, Europe and/ or worldwide. You can decided whether you value this factor.

Digging a little deeper what you really want to find out about, is the origins of the raw materials used in the clay and where and how they are made. With so much to chose from it is best to select a clay that suits you in function and then contact the manufacturer personally and find out what’s in it and where it comes from.

Understanding that a UK manufacturer will either produce or out-source the materials in the clays and then use machinery to mix them together to create their own signature clay bodies is a good base knowledge. Accessing information about this process is not readily available from websites and any information you may come across is not very informative and most certainly does not contain lists of ingredients. However in most cases if you ask the right questions then you will get the answers you need.

Also having an comprehension of what they do is of great value to any potter looking to be responsible and wanting to make concerned choices. 

The production of pre-made clay

The industrial production of making clays has been around for about 100 years. All pre-made clays are made up of a recipe and different methods are used to mix the ingredients, adding the right amount of water and then pugged to create the right consistency.

The two most widely used methods to produce clay bodies are the slip house method and the panmilling method.

The slip house method starts with dug clay being placed in large vats of water known as blungers.  It is mixed at this stage to create a slip. This slip is then run through a series of sieves and magnets to remove foreign or course particles. This is important as the raw clay contains all sorts of things from the ground such as stones or coal which could cause problems during the making and firing process later down the line.

The next step of the slip house method is to remove the excess water in a machine called a press filter. The machines have a special cloth inside that has been designed to allow only water to pass through it. The clay is pushed against the cloth, to remove the water and create solid slabs of plastic clay known in the industry as cakes. The final step is pugging to form the finished clay. A pug mill is a simple extruder, containing blades that cut and push the clay in one end and out the other. It is also at this stage that grogs and sands are added.  Unlike studio sized pugmills the exit point for the clay is appropriately sized to create 12.5kg blocks which can be cut at the right point to bag up and sell to the suppliers.

The panmilling method is not as widely used these days however is best for mixing highly grogged or flecked clays. Rather than the clay being added to a vat of water, the water is added to a revolving pan of materials to mix together and create lumps of clays that then go on to be pugged and bagged up.

Some manufacturers will consider sustainability as part of their business however others won’t value it in their choices. So lets ask them and support those that do!

So to wrap this up as I could keep waffling on forever, if your reading this as a potter wanting to make more ethical and sustainable choices start by asking your clay manufacturer a few questions, find out what’s in it and then research those ingredients.

If your a conscious consumer of pottery, be aware that a lot of ingredients used are unethically sourced including the clay itself and even if it looks gorgeous or the potter has a cute face, you may want to ask them a few questions abut the origins or their materials.