You’re playing with fire, quite literally.
Therefore, we encourage all who are thinking of buying raku or equipment for pit firing, to do so after having been on a course.
It is a popular, seasonal activity so there are plenty about, but do your homework as you want one with a good reputation and that pays particular attention to health and safety.
We at Hot Clay have given a lot of thought into the products we sell in this area, which will go some way to make it easier for our customers but without spoiling the creative choices that you can make in designing a kiln and choosing your equipment. However, we do appreciate it can be difficult for people new to raku/pit firing to know what to buy.
Our advice would be to start simple. For example, a kiln can be metal dustbin with body soluble ceramic fibre blanket* as the insulation. We sell a wire mesh jacket that will make it easier for storage and for securing the blanket to the sides. You can see other designs on YouTube and in books, but generally they all are enclosures of some kind, whether a simple metal shell or even a brick surround and then insulated. They have a hole in the front or underneath, and a hole at the top from which they exhaust. But before you decide, think ‘how you are going to retrieve your wares from the kiln?’. A sensible method is having a butter dish style, that allows you to lift the top part, leaving the ware(s) on a base, and a good base for example can be a bed of insulation bricks of a 23 grade, 16 is usually enough. This then gives you 360-degree access to grip your pot with the raku tongs.
If you decide on our mesh style, you will need to fix the ceramic fibre blanket to the sides. This is done with ceramic buttons which have 2 holes through which you can put nickel chromium wire through the sides of the bin or mesh and twist.
You can of course make a raku kiln out of insulating bricks on their own, but this is a level up in permanence and expense. And if raku is really your thing, you can buy off the shelf designs like Rohde’s which offer great value when you consider all the equipment which comes as a bundle.
Pit firing is traditionally a trench dug out of the ground but there are some designs which are above the ground using bricks. I would suggest using high alumina red bricks and not engineering house bricks unless you wish to line it with some insulation boards. And I would also be careful of using breeze blocks or concrete as these will perish with multiple firings.
With Raku using propane, you will need a burner, we have had one made for us which is perfect for a small sized (45 Litres**) and another for small to mid-sized kilns (75 Litres**), both have good safety features. If you make a bigger kiln, you will need to consider the size of the burner(s) and specifications, with the amount of pressure from the bottle of propane, the temperature you are trying to get to and the insulation you have used. This can get quite technical and although we are not experts we are well connected to those that are, and I am sure we can help, so do ask.
For any raku or pit firing you will need to know the temperature inside the kiln; this is best done with a pyrometer - a device which tells you the temperature and a thermocouple which is the probe which reads the temperature. The heat inside a kiln of this sort, is not uniform so you might need to make a couple of holes to poke your probe through to get a reading in several places. We recommend a type N; this is long and thin and not permanent thermocouple.
With the Raku firing, you might also need kiln furniture as you will need to consider the placement of the burner, you wouldn’t for example have the flame on the ware itself, most are often underneath the ware which is on a plinth. You may even need a spare cut of shelf to act as a splitter to divert the flame in a particular direction for better heat circulation.
Along side all this we do all the smaller equipment, which is very important, heat-resistant gloves, face masks (heat shields), safety glasses, and tongs. Do read all the product information with these, as it will give guidance as to their use.
And not forgetting our Vitraglaze Raku Glazes which is sold as both powder and brush on. The Vitraclay Raku Clay and Sibelco White Hand Building which will work well for raku and the pit firers. The later we are offer a range of thoughtful combustibles and metal foils and wire that will add interest to your work.
And if you are wondering what the fuss is all about, search online for ceramic artists like Stephen Murfitt, David Roberts and Sumi Von Dassow, which should give you the inspiration to give it a try.
*Please make sure you buy body soluble ceramic fibre or low bio-persistent as the other kind has serious health implications.
**make sure you take into account the insulation thickness when measuring volume.
See H&S link on Raku firing: SIM 03/09/11 Safety at raku kilns
