cardboard saggars

as I am missing the week of anagama and other wood firings at Nic Colin’s workshop in Devon this week, I have been left with a large number of pots which need firing in some more interesting way. it occurred to me to try Sebastian Blackie’s cardboard saggars, described in his book, Dear Mr Leach.

fifteen layers of newspaper and clay slip over a cardboard cylinder will last ten firings up to 1300 C, apparently, and unlike most ceramic saggars, which are enclosed, with a lid, and protect either the pot inside or the kiln from an atmosphere contaminated with carbon, fly ash or salt and other chemicals, these only partially enclose a packing of sawdust around the pot, which carbonises and should produce pots with black lower halves, and a certain amount of fly-ash glazing on the exposed part. cardboard saggars take  less fuel to heat up, and less room in the kiln than a traditional clay saggar.

I have spent a couple of days making saggars, getting covered in clay slip. the sawdust is oak, from a friend’s wood workshop; she is making an oak kitchen  for my neighbours. once they were made, packing the pots was a quick process.

as well as sawdust these four had bits and pieces of  vegetable matter from around the garden – dead field poppy plants, goosegrass, that sort of thing. I have a feeling that no trace of them will remain on the pots after firing, but it’s interesting to try things.

the shelves fit over these saggars fairly tightly, so they are almost like a regular enclosed one.

the next batch on the top layer are quite close to the kiln roof, and I had to pack the shelf and then load the shelf in with everything in place, which was not easy. although the pots on the bottom layers are sitting directly on the kiln shelf, I decided to pad the pots at the top, which meant that the saggars could not just be slid across the shelves with their contents.

it did give me the chance to photograph the arrangement of pots and sawdust. this one has copper carbonate sprinkled over the sawdust.

and there is salt in the little shell. that will produce a little more glaze around itself.

front right has both, front left has some steel wool.

both shelves in with some sweaty effort, not as bad as if the lower saggars hadn’t been quite stiff and supported the shelf in the points in between the supports.

now to fire it. Blackie says that he soaks at 500C for an hour, and then at 1300C for three hours, crash cools to 800C by opening the kiln door! I certainly am not doing that last part, it would set my shed alight, if I had a door to open, and I don’t, so I can’t. I am going to try my normal firing pattern and see what happens. the only thought is that it will fire differently because the saggars block the heat from travelling around the kiln, so maybe a certain amount of soak is a good idea. but my very slow firng at the 1200 to 1300 stage should have the same effect as a soak.

we got up very early this morning, it was so beautiful before six am. Tilda relocated her bedroom to the garden.

addendum

this experiment didn’t work! by 2 am the burners had gone out, as the cardboard saggars disintegrated into them. this morning I opened up, found the parts of the saggars exposed to the flame all charred and therefore unusable, took the front top shelf out, whereupon smouldering sawdust and cardboard smoked and burst into flames and had to be doused with water. I will have to take the burners off to clean them out, and re-think. probably my kiln has the burner flame at too close quarters for the cardboard saggars to work and I will have to make or buy ceramic saggars; I am not sure if you can buy them actually. making is quite simple, but will require another biscuit firing and enough new work made to fill the kiln properly – ie the saggars themselves create a lot of wasted space unless they are filled up with more pieces.

I am not too downcast, it was an interesting attempt, and needed to be tried out. art is all about play and experimentation.

I will see if I can make a big saggar type box with kiln shelves and fire all this stuff inside that then finish off the pack with glazed pieces on top.