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Post by niall on Jun 10, 2015 19:10:23 GMT
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Post by niall on Jun 10, 2015 19:15:41 GMT
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Post by rivergirl on Jun 10, 2015 19:43:03 GMT
Looking forward to the next stage! I filled mine with sand and bottles.
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Post by cannyfradock on Jun 10, 2015 21:26:09 GMT
Hello Niall
Nice set of pics!!....we all follow the same guide lines when building an oven but in 6 years of the forum (s) I've never seen 2 the same.
Don't forget to calculate your finished hearth height when laying the courses/slab below. Most people find that elbow height or about 1100mm is a good working height for the hearth.
Terry
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Post by niall on Jun 11, 2015 19:55:26 GMT
Thanks folks! I'll get some more pictures up soon. With the weather so good I have been cracking on with the build. Niall
Update: I have been removing the sand former this week and using tea lights to dry the oven slowly. All the sand is almost out but there is a big crack visible from the inside of the oven which I'm am concerned about. I have been filling a reoccurring crack at the same place on the outside of the oven and this now looks like the source! Can this be filled from the inside or will I have to start again? Help!!
Thanks in advance
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Post by niall on Jun 12, 2015 16:10:51 GMT
Pictures of the crack. Is this repairable? Thanks   |
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Post by cannyfradock on Jun 12, 2015 16:58:55 GMT
Niall It's difficult to see the extent of the cracks from those pics....could you take some more pics from further back? Clay ovens will crack but in 99% of the time, they are repairable with more clay.....and even with cracks...a clay oven will perform well. If the cracks are v.large then a re-build maybe on the cards but there will be a reason why this has happened. Your clay looks very pure....I use "puddling clay"....that's the stuff that gets used for parging up the banks on canals and ponds. As it's quite pure I add sand at a ratio of 2 parts sand to 1 part clay. Add enough water to bind then make tennis sized balls to build around the sand form..   ...or maybe with our recent bad weather you didn't get enough heat into the oven?.....I always say go slowly with the curing fires, but you may need something stronger that tea lights to start drying the clay out. You've already done most of the work with your oven stand/structure so if a re-build is in order, then at least it's just the sand form and clay dome to re-do. Terry |
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Post by niall on Jun 12, 2015 17:16:05 GMT
Niall It's difficult to see the extent of the cracks from those pics....could you take some more pics from further back? Clay ovens will crack but in 99% of the time, they are repairable with more clay.....and even with cracks...a clay oven will perform well. If the cracks are v.large then a re-build maybe on the cards but there will be a reason why this has happened. Your clay looks very pure....I use "puddling clay"....that's the stuff that gets used for parging up the banks on canals and ponds. As it's quite pure I add sand at a ratio of 2 parts sand to 1 part clay. Add enough water to bind then make tennis sized balls to build around the sand form.. ...or maybe with our recent bad weather you didn't get enough heat into the oven?.....I always say go slowly with the curing fires, but you may need something stronger that tea lights to start drying the clay out. You've already done most of the work with your oven stand/structure so if a re-build is in order, then at least it's just the sand form and clay dome to re-do. Terry Thanks Terry. I'll get some more pictures but I'm thinking a rebuild is on the cards. I used terracotta clay with a mix ratio of 2:1. The crack runs from the top to bottom. I'll remove the rest of the former tomorrow and get some pictures of the Grand Canyon! Niall |
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Post by cannyfradock on Jun 12, 2015 17:57:38 GMT
Niall If it's any consolation The first oven that I built was in my back yard. This was long before I created the forum. I knew nothing about insulation or any of the other fundamental things you do to make an oven perform well.....it was just a bricky's guesstimate. I've since built a couple of dozen ovens but my oven is the only one that doesn't function as it should. A re-build has been on the cards for many years now...  Terry |
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Post by niall on Jun 13, 2015 9:25:39 GMT
Thanks Terry. Your oven looks great! I have removed the rest of the former this morning and it's still standing. As you can see the crack is quite big! What are your thoughts?  Thanks Niall  |
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Post by cannyfradock on Jun 14, 2015 11:47:07 GMT
Niall It's a fair sized crack and I wouldn't expect something like that while the clay is still wet.....maybe as mentioned you should have added more sand to clay?....BUT, saying that, it isn't so large as the first pics shows. I would "gently" parge up the gap....inside and out with some fresh clay and sand and try to get a "putty" consistency. Then use your fingers to squezze the fresh clay into the crack. What the oven/clay needs at the moment is a hard crust which can be achieved by lighting some kindling fires. Use kindling stick so as the flames will start licking the inside of the dome. The fire hasn't got to be so intense but some flame from small stick will help form a crust on the clay. Build up the intensity of the fires over a week or so. Once the dome starts to take some serious heat the crack may open up a little further. Wait until the the heat has cooled from the dome a bit then parge up the gap again. As the oven cools the crack will reduce...or tighten up. If it were my oven i would probable cut a piece of chicken wire about 8 inches wide and use a clay slurry to fix it to the outside of the dome where the crack is.....this will stop it opening further. Another n.b.....At one of the largest food fairs in the UK..."The Abergavenny Food Festival" a clever chap called Richard Scadding who is the owner of www.earthovens.co.uk/ has a clay/earth oven that he uses every year. It has a horizontal crack about two thirds of the way up 3 times larger than your crack with a few large vertical cracks also. He still bakes Neopolitan (thin) pizza (which taste absolutely lovely) every 90 seconds. He does this at £6 a pizza over the the 2 X 12 hour days and has a never ending queue. Terry |
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Post by niall on Jun 15, 2015 15:20:45 GMT
Niall It's a fair sized crack and I wouldn't expect something like that while the clay is still wet.....maybe as mentioned you should have added more sand to clay?....BUT, saying that, it isn't so large as the first pics shows. I would "gently" parge up the gap....inside and out with some fresh clay and sand and try to get a "putty" consistency. Then use your fingers to squezze the fresh clay into the crack. What the oven/clay needs at the moment is a hard crust which can be achieved by lighting some kindling fires. Use kindling stick so as the flames will start licking the inside of the dome. The fire hasn't got to be so intense but some flame from small stick will help form a crust on the clay. Build up the intensity of the fires over a week or so. Once the dome starts to take some serious heat the crack may open up a little further. Wait until the the heat has cooled from the dome a bit then parge up the gap again. As the oven cools the crack will reduce...or tighten up. If it were my oven i would probable cut a piece of chicken wire about 8 inches wide and use a clay slurry to fix it to the outside of the dome where the crack is.....this will stop it opening further. Another n.b.....At one of the largest food fairs in the UK..."The Abergavenny Food Festival" a clever chap called Richard Scadding who is the owner of www.earthovens.co.uk/ has a clay/earth oven that he uses every year. It has a horizontal crack about two thirds of the way up 3 times larger than your crack with a few large vertical cracks also. He still bakes Neopolitan (thin) pizza (which taste absolutely lovely) every 90 seconds. He does this at £6 a pizza over the the 2 X 12 hour days and has a never ending queue. Terry Hi Terry. Yeah its possible I didn't add enough sand. It was a hot sunny day when I did the first layer so it could have dried too quickly? I have filled in the crack with some clay/sand mix and hopefully this will help resolve the issue. As I hate to take the first layer down as I have grown fond of it!  I will light the first kindling fire this evening and see how it goes! Thanks again for the help and invaluable advice. Niall |
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Post by niall on Jun 15, 2015 18:48:13 GMT
Some more of the build. Managed to get some reclaimed Dutch 1830 bricks off Gumtree for the surround and arch. ]  And some storage heater brick for the oven floor. I used a sand base before fitting the brick in to place.   |
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Post by niall on Jun 17, 2015 7:54:55 GMT
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Post by cobblerdave on Jun 17, 2015 8:43:16 GMT
G'day ukwoodfiredovenforum.proboards.com/thread/2190/hi-edinburghSeen is pop up in intro section. You've basically asked when do you remove the sand former. The answer is straight away, and the drying fires have to start straight away. This could be the answer to your cracking. Sorry I didn't answer you first post on this as I have not built a clay oven myself. I have however investigated it quite thoroughly as my oven was to be a clay one. I have also seen this come up again over the years. It might not be the whole answer as clay can have up to 15 per cent water content so once this is displaced it leaves a lot of space for cracks. At least you can get on with the knowledge that your oven will operate just as well cracks or not. The brick oven builders take every crack to heart as an imperfection to there building skills. Has my own got cracks. Pretty much.... But they are well hidden in the rough mortar work?  Regards dave |
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