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Pots are fired in a home-made kiln to around 1300 degrees Centigrade using only wood.

This technique was developed by the Ancient Chinese but is rarely used today. It is labour intensive and physically challenging.



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So why bother?

Because wood firing gives results that are unique to the process. As the flame passes through the kiln it deposits wood resins on the pots, enhancing their surface colour.

Our pots are generally not as brightly coloured as those from an electric kiln, but wood-fired pots gain a characteristic ‘depth’ of colour  -  a deep richness  - which is not achievable by any other means.

The kiln has a capacity of 35 cubic feet. It is a ‘downdraft’ kiln with two fireboxes. The fireboxes are underneath the chamber where the pots are stacked. A downdraft kiln is quite efficient, putting the flames from the fireboxes to good use by forcing them all the way round the kiln, up and down, before they exit through the chimney in the bottom.

It takes about 15 hours of continuous stoking to reach the temperature we need – around 1300 degrees Centigrade.  Our record time for firing the kiln is 12 hours. This is quicker than some would recommend for a wood firing, but the pots didn’t seem to mind – none broke and the glazes were the same as usual.

We do warm the kiln up gently for two or three days prior to the main firing. We light a small log fire in bottom of one of the fireboxes and chuck a log on every few hours during the day, with a big piece of hardwood to take it through the night. The old potters had names for this process. They called it candling, or water-smoking. We like the term candling. Candling calls for very little effort and keeps the temperature of the kiln between 50 and 150 degrees Centrigrade.  It is usually around 70 when we start the period of continuous stoking – the firing proper.

The wood resin that flies through the kiln during the firing is called ‘fly ash’.  Fly ash is very sticky – it sticks to almost everything. It will bond a pot to the shelf it stands on unless something is done to stop it.

One of the few things fly ash won’t stick to is sea shells. When the pots are put in the kiln they are all placed on seashells - scallop shells from Abersoch beach. The shells make a mark on the bottom of the pot.  These and other wood-firing artefacts are part of the pot’s individuality and charm, but they may not appeal to those who like their pots factory-perfect. You either love the gift of raw flame to clay, or you don’t.

The process of wood firing has certain rules which you ignore at your peril. The golden rule is that wood must be well seasoned and bone dry. It is virtually impossible to achieve the high temperatures required with damp wood. We use thin planks of Western Red Cedar, off-cuts that have been lying in a local sawmill for years. We cut these well-seasoned planks to the required length and place them under cover for a couple to months, stacked in layers at right angles to one another so plenty of air can get to each plank.

We once fired the kiln when everything was very damp, during a wet spell in early January. The wood we were using had been under cover, but the damp seems to get everywhere at this time of year. It took 24 hours of continuous stoking to reach temperature, and even then we were a few degrees short of the ideal – the pots in the hotter parts of the kiln (the top) were okay, but those lower down were a bit under-fired. We also used twice as much wood as normal.  Twenty four hours hard, continuous work without a break or a wink of sleep was a challenging experience, and not one we wish to repeat.  We no longer fire the kiln during the six weeks either side of Christmas.

Our kiln reaches different temperatures in different parts of the chamber. When it is 1280 Centigrade in the middle, it is 1300 in the top and 1240 in the bottom. If we ‘soak’ it, which means try to keep it steady at 1280 for an hour or two to even out the temperature, everything just goes up a level – the top goes up to 1320, the bottom to 1280. We find its best to accept the temperature difference and work with it, using different types of glazes in different parts of the kiln. (Potters might be interested to know that we use a single cone to judge the firing. It is a Cone 9 cone, placed near the spy-hole, on the middle shelf. We like to see it well bent, with its tip touching the shelf, but not collapsed in a heap. This is most critical for ash glazes. If the cone is only slightly bent, the ash glazes will not be mature. If the tip is touching the shelf, the ash glazes will have plenty of colour. If Cone 9 is collapsed, the colour will be burnt out, and the pots will be a uniform dark brown)

Pots on the very top shelf are exposed to the most flame, and therefore the most fly ash.  We tend not to put any glaze on top-shelf pots. At the height of the firing, fly ash sticks to the naked clay, effectively becoming a thin layer of glaze. Some purists like pure fly ash pots best of all (pots 6, 7, 31, Main Gallery).

Another aspect of wood-firing is that the results are never the same twice. With an electric firing, the firing cycle can be rigidly controlled by computer, and identical pots produced in different firings. With wood-firing there are so many variables in the process that no two firing cycles are ever quite the same, and no two pots ever quite the same. Every wood-fired pot is therefore unique. And you never quite know what to expect when you open the kiln – it’s like peering into your Christmas stocking, every time.