Tips for making work to Raku Fire
The best clay to use is any white/pale buff firing stoneware clay that has a little grog in it which helps with the thermal shock.
We recommend not using a ‘raku’ clay as they can be quite heavily grogged and some have iron in the body which makes crackle white glaze go a rather odd pink colour.
We use Valentine Clays B17C grogged for all our pots we make for the workshops.
Complicated shapes with lots of texture aren’t so successful. Simple forms and surfaces show off the beauty of the raku glazes the best.
Raku pots are non functional as they remain porous after firing so enclosed forms with small neck openings work well. Tall and thin rather than large, open and wide.
Thrown work is great so long as it is even and not thick. Evenness through the work is very important as work will cool rapidly and this can cause stress in the change of thickness, causing cracking.
Very small pieces such as pendants etc. will be fired at our discretion, they can be very tricky to handle with our large tongs.
Handbuilding also works well if extra care and attention has gone into the joins, again the sudden change in temperature will find the weakest point and crack can occur. Slab dishes are good so long as they are not too big (25cm max) and again not too thick.
If work can cool quickly the crackle results will be much better. Thick work hold the heat and you may not get any crackle or lustres at all.
Sculpture - We have had some amazing results form firing sculptures but again please not too thick.
For naked raku, horse hair firing your pots will need to be burnished for it to work well. Either apply terra sigilata or use a smooth pebble or spoon to polish a firm leather hard piece. There are lots of videos on Youtube about how to best achieve this surface.
All work must be bisque fired to 1000 deg c.
We should be able to fire between 6 - 8 pieces. Large pieces take up far more room in the kilns and we may not not get round to firing them.
Please look through our photos and you will get an idea of what works well.
If in any doubt then please get in touch and we can confirm if you are on the right tracks.