Out of the Fire by Jane White; finished bowl

My work is constantly evolving, exploring the beauty of the form by referencing the natural world around me, and looking at the enduring qualities of the ancient pots in national collections across the world. I love the simplicity of these pots with their perfectly balanced forms, and I’ve tried to translate this knowledge into my own work. 

I discovered the process of pit firing about 20 years ago while studying for a degree in ceramics, and I immediately knew it was a way of working that I strongly identified with, and that I’d found my creative direction. I live on an isolated farm, which means that having a large pit firing is not a problem. I also love adventure, enjoy taking risks and chances, and traveling to remote parts of the world where few people venture. So, the process of pit firing seemed ideally suited to my personality and my lifestyle. I love the serendipity of the technique, and the fact that the pieces seem to have been created by nature, by the alchemy of organic material combined with the element of fire, which transforms the surface of the clay into myriad different patterns and colors. It is an exciting but risky technique, resulting in work where surface and form seamlessly unify, and, as in nature, each piece that survives is totally unique. 

I use a professional raku clay body from Valentine Clays called Ashraf Hanna. It fires white, has a high alumina plastic ball-clay content, and contains 58% molochite, so it can withstand the extreme thermal shock of the uncontrolled rise and fall of temperature during a pit firing. 

Out of the Fire by Jane White; African Wooden Spoons sidebar

Creating the Form 

My vessels are started by pinching out the initial form (1), then slowly adding coils to build up the shape (2). I use a collection of African wooden spoons while building the shape, beating the outside of the clay form with the flat spoons (3), and pushing the inside of the form with the curved ones, while also smoothing out the interior surface. I also use metal kidney ribs and a Surform tool to remove excess clay. 

When you are happy with the general form, turn the piece upside down and center it on the pottery wheel. Using turning tools, thin and even out the thickness of the walls, further refining the shape of the form as well as tidying up the foot (4). Uneven thickness in the clay walls will cause stress in the pit firing as it cools, making the piece more likely to crack. 

1 Begin with a ball of clay and pinch out the initial form. 2 Make coils using a round loop tool, and begin adding them to the form.

3 Use a flat spoon to beat the clay and develop a narrower base. 4 Use the wheel to trim and refine the foot of the vessel.

Burnishing 

Leave the piece fixed to the wheel for a short time to firm up a little before burnishing, which is done on the wheel using a polished semi-precious stone (5). Irregularly shaped vessels have to be burnished by hand. I have a collection of stones of all different shapes and sizes. They have to be hard-grade stones or they will lose their polish and not work as well—my favorites are jade and rose quartz. I burnish to compress the clay and push the grog back in, which creates a smooth surface on which to apply terra sigillata. 

5 While on the wheel, burnish the vessel with a polished stone.

Polishing 

When the pieces are bone dry, brush three layers of terra sigillata onto the surface with a soft wide brush (6), and immediately polish the pots with a soft cloth until you get a sheen (7). I use a piece of synthetic velvet. Tip: After the polishing, do not touch the surface of the pieces as all your fingermarks will show. At this stage, the pieces are also very fragile. Bisque fire the work to 1688°F (920°C). 

6 Brush terra sigillata onto the surface of the pot. 7 After applying the terra sigillata, polish the surface with a soft cloth.

The Pit 

My pit is actually a long trench, dug many years ago with a mechanical farm digger. It is approximately 16 feet 4 inches (5 m) long, 6 feet 6 inches (2 m) deep, 3 feet 3 inches (1 m) wide at the bottom, and about 9 feet 8 inches (3 m) wide at ground level as the sides have eroded over the years. It is now lined with concrete blocks to stop the sides from disintegrating further over the winter months (see 10). The blocks do eventually break up, but they are easy and cheap to replace compared to the cost of lining the pit with fire bricks. 

Packing the Pit 

I put about 8 inches (20.3 cm) of hardwood sawdust into the bottom of the pit. Different types of sawdust and wood shavings all give different color results, but that’s the fun of experimenting, and in any case, no two firings are ever the same. I have found that hardwood sawdust is denser and tends to give darker, richer, more interesting firings. 

I sprinkle dry salt and dry powdered copper carbonate on and around the pieces in the pit. If you apply these in a liquid form, then you must make sure the pots completely dry, ideally by placing them in an oven or the kiln, or they will crack in the pit firing. Salt will give orange colors and the copper carbonate will give reds in reduction, which is why it’s important to try and seal the pit with metal sheets while it’s still burning slightly. If you cover it too soon, then you create a smoky atmosphere, and the pots will go black, and there is no fire left to search out the oxygen it needs on the surface of the pots, which in turn will turn the copper blacks and greens to red. 

8 Pack bisqueware closely together in the pit and cover with the organic material.

Next, I carefully place all the work in the pit, quite close together, with the pieces touching each other (8). Some of the vessels have copper wire wound around them—this will give some random black lines or red flashing if reduction has occurred in that part of the pit. Whatever part of the pot is buried in the sawdust will be black, and sometimes the carbonized black surface will turn silver if reduction has occurred. Packing the work close together helps slow down the cooling and keep the heat in the pit, and it will also encourage reduction in the narrow gaps in between the pieces. 

Pit Firing Materials 

It is important to dry the organic materials such as seaweed and coffee grounds before use, to enable storage prior to use, and to prevent them from turning into mushy compost. 

Dried seaweed gives oranges and reds. Dried oranges and lemons give blues. Dried vegetable and fruit skins and stones give browns and greens. Dried coffee grounds also give blues. Driftwood gives oranges. Nutshells and horsehair leave marks on the pieces. 

The pit firing materials are packed in and around all the work in the pit, and I also sprinkle more copper carbonate around the bisque ware (9). Caution: Wear a properly fitted respirator when working with raw metals. 

9 Sprinkle dry copper carbonate in and around the pots. 10 Cover the pit with wire mesh before starting to load on the wood.

I place a metal grid across the top of the deepest part of the pit, just above the work (10), and then start loading wood on top of this (11). I use fallen branches and old, dead, windblown wood—collected from around the farm and woodland edges. Next, straw is woven between the wood, and wastepaper and old cardboard boxes are piled on top, so the fire will catch hold easily and give a fast, hot, clear burn (12). The fire will burn for about 3–4 hours (13) before I place metal sheets over the top to slow down the cooling cycle, which will help reduce cracking and also encourage reduction (14). 

The pit is unpacked 48 hours later (15). The pieces are all wiped clean with a damp cloth—don’t wet them if possible, as this will cause the salts within the piece to cause corrosion on the surface. Then, I apply a thin film of a micro-crystalline wax, but beeswax will also work. Polishing the pots is usually a family affair. It’s very rewarding to see all the beautiful colors and patterns come to life—like dropping a pebble into water. 

11 Load the pit with wood. I use fallen branches from around my property. 12 Cover the wood with straw, cardboard, and waste paper before lighting the fire.

13 Once lit, the fire will burn for 3–4 hours before being covered with sheet metal. 14 Add metal sheets on top to slow the cooling cycle and encourage reduction.

15 After 48 hours, uncover clean, and admire the pots.

Pit firing my work is always an exciting process. The sense of discovery after lifting the metal sheets and seeing all the pieces lying buried in the ash below, just waiting to be discovered, will never cease to amaze and enthrall me. 

Jane White has a degree in ceramics with glass, and is a fellow of the Society of Designer Craftsmen. She has been pit firing ceramics for the past 20 years and has exhibited widely in the UK. She is also the author of a book published by the Ashmolean Museum, Alan Caiger-Smith and the Legacy of Aldermaston Pottery. Visit her website to see more of her work, www.janewhiteceramics.com