Raku at Gladstone Pottery Museum

Raku at Gladstone Pottery Museum


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On one of the hottest days of the year, I attended a raku firing workshop at Gladstone Pottery Museum led by Tez Roberts, a self-proclaimed “mud slinging pyromaniac”. Gladstone Pottery Museum is only down the road from The Sutherland Works, so it didn’t take me long to walk there. We started the day by practicing mark making on some bisque fired bowls (clay bowls that have been through one kiln firing) that Tez had prepared for us, using masking tape and some of Tezs’ raku glazes. We had to apply the masking tape and then paint the glaze(s) onto the pot. The masking tape has to be stuck down pretty firmly to make sure that the glaze doesn’t seep into the wrong place. It’s not as easy as you think to stick a thin long piece of masking tape on the inside of a dry bowl. Once we’d finished our first bowl, we went off to the raku kiln which was on site at Gladstone to fire our pieces. Here are some pictures of the pots before and after the glaze was applied.

While we were waiting for the glazes to fully mature in the raku kiln, Tez told us all about the history of raku, from the Japanese tea ceremonies to the present day. 

When it was time to take our bowls out from the kiln, everybody had a turn to take a piece out using long raku tongs. It was well managed, the safety equipment was beyond what I’d ever seen before: heat resistant gauntlets, aprons that won’t melt, professional masks to protect participants from the fumes and safety visors for those closest to the raku kiln.

Here are some pictures of the first raku bowl I created at the workshop.

Before heading on to the second pot, we looked at the pieces that we’d just taken out of the raku kiln. We can always learn from what we’ve done previously. We’d given our pots a little scrub to remove the extra carbon. The black marks on my pots are where the masked off areas were on the pot, where I didn’t apply any glaze. The fine black lines in the white glaze are where the carbon has got in between the cracks – these can’t be removed either.

I’d noticed the reduction effect of a copper glaze on the inside of someone else’s pot and thought “yup, I want that”. As you might have noticed from pictures of my pots, I generally don’t venture away from geometric shapes, the kind of designs that I’ve witnessed and practiced all of my life (it’s in my blood, you can read more about me here), but I kept it simple for these raku pots. If I’d had more time, I’d do a full geometric pattern on a raku bowl, as big as possible! I’m not sure I’d be able to lift it out of a raku kiln though 😄.

None of my designs were planned beforehand, it’s just what I’m drawn to.

Looking around Gladstone Pottery Museum

During the second firing, I had a look around at Gladstone Pottery Museum. For a bottle oven lover like me, the shop was somewhere I could have easily spent money in. Books, cards and various pieces of work made by local makers which feature a bottle kiln. If you can’t make it to the museum, you can view their online shop.

‘Bottle Ovens and the Story of the Final Firing’ is a book I’ve been meaning to purchase for some time as it details the history of the last bottle oven firing at the Sutherland Works – where I’m writing this blog post from right now. You can find the book here. But more on that another time.

The picture above shows one of the saggars that were used at the final bottle oven firing. This one is kept at the Gladstone Pottery Museum.

My favourite part of Gladstone Pottery Museum is the colour gallery, particularly the lab area with all the old pots of stains. Who doesn’t find labelled jars with stains and oxides visually appealing?

I could tell when it was time to get back to the raku kiln for the second unloading as I could smell the wood shavings burning. Here’s how my pot turned out after a scrub with a scouring pad and a bit of water. The pots still have a bit of a smoky smell, even a few weeks later. Little reminders of the process. I guess it takes a while for that to fade. 

After the fire

Tez is one of a very small amount of female potters that I’ve met that have in-depth knowledge of glaze chemistry and the materials used.  There’s not many women like her around. It was refreshing to be able to talk about glaze chemistry with a woman on my wavelength for a change – it’s generally men that seem to get into the nitty gritty of glaze chemistry, especially in Stoke on Trent where there’s only a few experts in glaze technology remaining.

If you’re looking for somewhere to learn about raku, or if you’re a pottery studio looking to book a raku class, I wouldn’t hesitate to recommend Tez. Even better to experience it in the grounds of an old pottery factory/museum. It’s something that any clay enthusiast should experience in person with an instructor that is an expert in their field. It’s not something you should try to do on your own at home. A responsible raku instructor like Tez will make sure that all of the safety measures are covered.

The 17th of July 2021 was also national raku day.

What makes a Raku firing different from a Stoneware firing?

Raku firings generally take place outside and during the warmer months. They don’t often happen in the winter as there is lots of standing around with waiting for pots to get to their optimal temperature,  it can be a very smoky environment so good ventilation is needed. Pots are fired to around 1000 degrees centigrade. When they have reached the required temperature they are taken out of the kiln and cooled down quickly. It can either be plunged into water or placed into a barrel of combustible materials first. 

When pottery is fired in a conventional kiln, it reaches top temperature at a steady rate and is allowed to cool down slowly. In raku firings, pottery is fired and cooled down quickly. The process takes about 1-2 hours: in comparison, a conventional kiln firing takes around 24 hours including cooling down time (dependent on the size of the kiln and the heat work in the bricks). 

Raku kilns use a gas supply from a bottle. It is faster to heat pots in a gas kiln than it is an electric kiln.

The Western method of raku differs from the traditional Japanese method. The method that was used during this firing at Gladstone Pottery Museum was the Western method which has been in existence for around 50 years.

Any type of clay can be used but clays specifically developed for raku firings are less likely to suffer thermal shock. As the clay body does not reach its maturing temperature, the clay will still be porous. Raku pots are for decorative purposes only and should never be used for food or drink. The glaze will have cracks in it as can be seen in these microscopic pictures below, these are the raku pots that I had fired at Gladstone. It’s more noticeable to see the cracks on the white glaze but present in darker glazes too. The raku glazes below are blue, copper and white (in that order).

Here’s a video of some of the highlights of the day.