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- 1 large galvanised garbage bin plus lid (around 75 litres capacity)
- Back-up fibre, approx, 2.8m (don't need hotface fibre as kiln is only going to around 1050°C
- Fibre adhesive (QF180 or similar)
- Fibre protective wash (zircowash or similar)
- High temp wire, (20 gauge or thinner)
- Adjustable metal hose clamps (joined together to anchor fibre folded around top of bin - see photos)
- Tin snips, small head
- Hammer and 3" nail (or drill and small drillbit)
- Buttons for securing the fibre (old stilts OK)
- Sharp strong scissors (less fibre dust with cutting) Stanley knife for cutting port and flue
- Pliers for tying buttons
- Paper to make template of bin shape
PROTECTIVE CLOTHING etc
- Dust coat
- Disposable latex gloves
- Good quality close fitting dust mask.
Using a marker pen, draw a 12cm circle near the base of the bin positioned half way between the side handles and 2cm up from the bin base seam.
Punch (or drill) a short line of holes inside this circle using the hammer and nail.
Work the tin snips into this starting point and begin to cut gradually towards the circle edge and continue until the circle can be removed. This cutting will produce a spiral cut. Avoid completely closing the snips while cutting to avoid unevenness.
Remove a circle from the lid in the same manner using the raised centre detail as a guide. This lid hole will become the "flue" and should be larger than the port.
If the bin lid has only one side handle you can make another out of coathanger wire and mount it opposite the first handle by drilling holes and bending the wire through. This makes handling a very hot lid much easier and helps to protect the fragile fibre around the bin rim by giving you better control of the lid.
Holes for wiring buttons to support fibre
Punch or drill holes in pairs at regular staggered sites all around the bin, in a three, two pattern, locating these with reference to the port at the base and ensuring that the top tie holes are not more than 10cm from the rim. Do the same with the bin lid.
Inside of lid showing how the stilts have been placed to maximise support of the fibre around the flue hole
Inside view from the floor of the kiln looking out through the burner port. Note how the stilts have been arranged to maximise support of the fibre around the edge of the hole.
View of the kiln showing spacing of the stilts supporting the fibre lining. Also note the use of a square shelf with the corners cut off make a 'roundish' shelf.
If you intend to use a probe for heat measurement then it is best to cut and drill appropriate holes in the kiln at this stage, before you fix the fibre to the walls.
Simple thrown mount for temperature probe. Made such that the probe when fully inserted has the probe tip about 5cm into the kiln chamber. For loading and unloading the probe can be slid outwards and still rests within the mount sleeve, this protects the probe against accidental damage but avoids the need to place the hot probe somewhere else.
Cross sectional view of my probe mount. The fibre protects the bolt heads from the kiln's heat.
Cutting and fixing the fibre panels
Create a newspaper pattern of the bin interior walls ignoring the burner hole at this stage. Tape the paper in place to the inside of the bin at top and bottom, then work around the inner wall of the bin taping the paper at top and bottom until you have at least a 5cm overlap with the starting point. Extend the paper template about 10cm above the top of the bin rim to allow for folding the fibre over. The template will produce a slightly tapered form when removed from the bin and spread out flat.
Dress in protective clothing, gloves and mask to avoid fibre contact on the skin and inhalation of the fine fibres.
Using the template laid on top of the fibre cut out using scissors. NOTE: Do not remove any "top edge" fibre as this will become the top overlap.
Lightly press the base of the bin onto the remaining fibre sheet, the extended ridge on the bin's bottom will imprint a circle pattern. Cut out the fibre base pad allowing an extra 3cm or so all around so that the pad will fold up the walls slightly when placed in the base of the bin.
Place the lid down and trace around it with a marker pen, then cut out a little distance inside the line for the fibre lid insert.
Coat the base of the bin with fibre adhesive and squeeze the base circle into the bin, allowing the edge to slightly fold up the walls. The base pad does not require any buttons to hold it in place.
Loosely fit the fibre wall lining in the bin and check that it sits evenly all around, with the bottom edge overlapping the upturned edge of the base pad. This will ensure that there is a good seal between the base fibre and wall fibre.
Beginning near the bottom, spread some fibre adhesive around the inside of the wall and press the fibre into place. Continue the process in a circle around the bin working upwards to the top until the fibre is fixed in place.
If you are using stilts or similar as retaining buttons then you can make a 'staple' of the HT wire and push it into the bin from the outside through the fibre, gently supporting the fibre with your gloved hand (don't stab yourself!) Place the stilt in place against the fibre and twist the wire, then tighten with pliers. Cut off any excess wire and fold over the sharp edges flat against the fibre. Avoid over-tightening the wire, it only has to hold the fibre snugly in place.
If you are using normal buttons then you will need to thread the wire through the button, then poke through the fibre and bin wall, twisting off on the outside. Again fold any sharp edges flat against the metal.
The excess fibre above the top of the bin can now be cut into segments down to the top of the bin rim to allow the excess to be folded over the rim. Fix fibre in place with metal hose clamps that have been ganged together to make a loop of appropriate diameter.
Using any scrap fibre a second layer may be possible for the lid insert. If so, insert the scraps first then the whole piece, glueing into place with fibre adhesive. Place buttons or stilts as per the previous step, ensuring that the fibre is supported as close to the flue hole as possible.
Carefully cut out the port hole and flue hole with the Stanley knife attempting to produce as little fibre dust as possible.
I recommend protecting the fibre with a coat of fibrewash (Zircowash it is called here) which forms a toughened crusty layer on the fibre. It is particularly good at reducing abrasion where the lid sits on the body and also minimising 'flame abrasion' around and opposite the gas port at the bottom of the kiln.
I have found that an 11"x11" shelf with the corners cut off makes a great 'roundish' shelf for the kiln. I just use three firebrick off-cuts as the shelf supports, with another firebrick piece as a flame splitter to divide the flame and get better heat distribution.
When firing the kiln I use a piece of kiln shelf on top of the lid as a damper to adjust the flue opening as required.
Note that the lid only rests on top of the wrapped over fibre. Be very careful when placing and removing the bin to avoid damaging the fibre.
The bin wont stay shiny for long believe me! Even the reduction bins quickly become discoloured and distorted.
The Finished Raku Kiln is best stored inside a very large plastic bag such as those used for lining wheelie bins. This protects the kiln edge from bumps and the ravages of breezes.
These notes have been developed from a set given to me by Judy Roberts, a raku potter who also lives in Melbourne, Australia. I have amended and added to them in accordance with my experiences while building my raku kiln. Many thanks to her for the information.