Raku firing is a funny and exciting experience

Bruno Vinel is retrieving a piece of pottery from the kiln at 1,060 oC

Bruno Vinel, Ceramics Today editor, shares his experience attending a Raku firing workshop on the 6th of June 2021. It’s a reflection on what went well and what he could have done better.

Back in August 2018, I helped Turning Earth on their stand at Makers Festival Victoria Park, London and took part in a Raku firing tester session. It consisted of glazing a bisque fired pot and looking at how it was fired by the potter doing the demonstration.

I was impressed by the experience and wanted to try it again. So a few weeks ago, I was excited when I finally signed up for a half-a-day Raku firing workshop delivered by Austin Gannon in Birmingham.

It was a memorable experience full of exciting surprises and some mixed bag results. These are the highlights and lessons learned.

Choosing the right workshop

If you Google for Raku firing workshops, you may find many different options. Raku firing is popular and organised by many pottery studios and potters. So how do you choose the right one for you?

If you have zero experience making pots, you should be looking for an introductory session lasting a couple of hours:

  • The session will start with an introduction to Raku firing and health and safety considerations.
  • You will be offered one or two pottery pieces already bisque fired, ready for glazing.
  • You will be applying a glaze or combination of glazes. Glazes are mate and quite unattractive before firing, and you will be looking at glazed samples or pots to decide which one to use. Application is quite simple, often done using a brush, with two or three coats.
  • Once dry, your pots will be loaded in the kiln and fired to 940-1,060 degrees Celsius.
  • The potter or technician will retrieve them red hot from the kiln and placed them into post-firing reduction containers with some materials like sawdust, hay or newspapers.
  • Once the reduction is completed and the pots have cooled down, they will hand them to you for a good scrub and cleaning to remove the residues of the reduction process.

After that experience, you may like me want to try it again and learn more. I would recommend that you sign up for a half-a-day or full-day workshop.

Turning Earth Raku firing taster session at Makers Festival, August 2018, Victoria Park, London

Making your own pieces for Raku firing

If you are making pots, I suggest that you discuss with the workshop organiser which type of clay you should use and what characteristics your vessels should have to resist the stress during the firing and reduction process.

You can throw or hand-build your vessels. It is recommended to make enclosed shapes that resist better to the stress caused by the firing process. Large open bowls will most certainly crack.

There is no best way to make pots for Raku firing, but Austin Gannon recommended that pieces should have walls as even as possible to ensure that the heat distributes more evenly.

Using grogged clay is recommended as it will offer better resistance to heat stress and cracks. Any clay that contains grog will work fine. One of the vessels was made with Ashraf Hanna Raku clay. It is good clay to throw and it withstands the most extreme thermal shock, thanks to its high content in molochite.

Out of the four vases fired (see pictures at the bottom of the article), two survived the firing process. One vase was made with Ashraf Hanna Raku clay and the other one with paperclay porcelain. The paperclay porcelain didn’t contain any grog but the vase survived possibly because of its shape. These two vessels had rounded edges and enclosed shapes, which are more resistant to heat stress and cracks.

The other two vases didn’t have such a good outcome and cracked. I used porcelain thrown vessels that were initially planned to be fired in my electric kiln. Their walls were fine and straight. Despite all the precautions that Austin took to fire them, raising the temperature slowly, they developed cracks during the cooling and reduction process.

I used Mayco Colors Raku glazes for the decoration: Oxbow, Blue Topaz, White Crackle and Peacock Matt (see pictures at the bottom of the article). I loved the Oxbow glaze, which reminded me of the traditional Chinese red glazes, and the Blue Topaz, which was my favourite one with its bright colour. The Peacock Matt, a copper-based glaze, developed iridescent shades of blue and purple during the reduction phase, which gave the vases an fantastic personality.

I enjoyed so much the experience of Raku firing. The workshop was full of surprises, and it was lovely to meet Kate and Hilary who took part in it. I learnt a lot, thanks to Austin Gannon’s extensive experience, which he was sharing abundantly.

I am looking forward to the next Raku firing workshop, and this time, I will come more prepared, with vessels that, in principle, should survive better the firing!

%d bloggers like this: