CLAY OVENS
After experience of building clay ovens with the Apricot Centre in Manningtree Essex, the decision to build on at the People's Community Garden was taken. On very sandy loam there was no clay so a local art college helped us out with their waste clay. Since then clay has been turning up in friend's gardens regularly. Having been asked to build more since i have bought grogged terracotta from pottery supplies from the internet. Using clay from the garden is fine but when we did it i cut my feet a bit and though not badly, i d rather pay and use bought clay with groups. I estimate we used 75kg on the rather large oven at in the pics below but there is a real cost in delivery so go with local suppliers and pick it up if you can.
The process is simplified to:
- Need a base to raise oven off ground, make the oven where it will end up as very hard to move.
- Need clay, sand and straw. Easy recipe is 2 sand : 1 clay plus as much chopped up straw as it will hold.
- Need people as its more fun, especially arm in arm in a circle singing "mud, mud, glorious mud".
There are other tips, but i have got round problems with inginuity before and they have worked. Check out these website for similar tips from other people:
INSTRUCTIONS: LOOK AT PICTURES BELOW BUT THESE WORDS MAY HELP EXPLAIN IT BETTER.
So make a plinth for easy access to the oven and to keep tiny tots out. Make the willow support with a hole at front and a hole at the top. Making Clay see below. Cover wicker inside andout with manure (this stops the support from burning instantly and was surprising the most enjoyed bit of the day. Wear gloves and wash them afterwards). Cover the manure with newspaper to remove any risk of contamination and to provide a smooth surface to put clay. The inside of the clay oven starts where the paper is so dont make your wicker frame too big like we did, yet it still works.
Making the clay means coating the sand particles with the clay and the best way is to use your feet to stomp it together. This is called "PUDDLING". A ring of clay helps the wicker frame in place and thereafter load after load is puddled and added on top of the newspaper to form the oven. 2 spades sand to 1 clay, this ratio can be scaled up. some moisture is needed but judge this as its easy to add too much. We did this for the first layer and then added straw for the second layer but i cant justify this so i would use straw from the start and you add as much finely chopped straw as the mix will hold. To know if its done do the drop test. Hold a ball of clay out from shoulder height and if it splats its too wet and add sand. If itstays kinda ball shaped you're getting there. If it crumbles it needs more clay. The sausage test invovles rolling the tarpauline upon which it is vital to puddle, to bring in the mix back to the middle to puddle it some more. If it rolls well into a nice sausage you are doing well. Always puddle it at least once more time than you think. If doing industrial sized quantities to build a cob house you can drive back and forth over the mix with a tractor. Cob building was the dorb of the wattle and dorb houses and is a sustainable long term material. I saw the clay mix (cob) being put into long sacs and this can create sinuous walls which when dry form earth houses.
Build up the clay as thick as you can. Dont make it too wet or it
will slump and we found bizarrely that it worked best from the top
down. one large hand thick is minimum. Leave for at least 24 hours but
a week would be better. Then have afire and set it. The fire needs to
be for a whole day and start early if you cant leave the fire going
over night for health and safety reasons. It is done when the clay has
changed and set and the wicker has been burnt away. Then Fire it up a
few hours beforehand, cook and eat, a lovely celebration for all that
work. People love it.
Think through your health and safety in construction, firing and food preparation stages.
I wil send you copies of mine only if you read them and give me
feedback please as we can cooperatively ensure all things are thought
of.
This was the end of the DAY. But a few days later i returned and mixed the rest of the clay, sand and this time STRAW. It is amazing how well the straw binds the mix. It was fired up and now looks like a snail. To protect from the elements cover with a tarpaulin in heavy rain but it should last a few years outside.
Then after the community garden clay oven was made i went home and we found some clay in the vegetable patch whilst digging at home so in five hours we had built another oven with some interesting design features. First the base was a huge log, some bricks and paving slabs which were lying around.Then the clay was dug up and without any sand was puddled or swidged by foot, (the clay is cracking 3 months later but still works as no sand was used) Having learnt from day 2 at the community garden that its good to have straw, we looked arround and used cowparsley as it was all about us. The cowparsley needed twisting and cutting to rid the hollow stems from creating air pockets in the oven. Then main idea this time was to be able to boil a kettle on the top to get a multi use from the oven. As the clay was very firm we also decided that we didnt need a wicker inner and bricks would do just fine. It culminated with finding an old charcoal burner that was on the recycling pile and it means that we have cooked chicken in the oven and rice on top. Perfect.The lid of the stock pot acts as a door and we use BBQ tools for the cooking. The paving slab cracked a tiny bit but still works and thought the clay is cracking it gives character to the oven. So this was a quicky version but the size of the community garden oven is much bigger and i would use the above method for longer lasting clay ovens.
Next Mission is to build a clay oven under a metal bath to create a hot tub. Imagine having a relaxing soak follow by a pizza. Yum isnt that what life is about.
