jwyno
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Post by jwyno on Jun 19, 2012 15:11:44 GMT
Here is a more close up of when the clay was in place and looked quite good....initially. Unfortunately we did this the weekend we had heat in the high 20's and then huge amounts of rain. Even covered, the clay remained quite wet and then with added heat again a few days later in the low 20's, the cracking was quite severe. End result is that presently i have removed all clay and will basically start this again when the weather looks more stable and using a much drier mix. For now i am going to try to break down the clay again, and slowly wet it to see if i can reuse this towards the weekend. Attachments:
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jwyno
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Post by jwyno on Jun 29, 2012 18:18:15 GMT
So i removed the clay and basically started again. I used a much drier mix, mixed it by hand, rather than in a mixer, and also applied by hand and all in all, i am much happier with the end result. The clay seems to have bonded much better with the dome, and there is visbiliy less cracking and no air under the clay so all in all ...really pleased. Attachments:
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jwyno
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Post by jwyno on Jun 29, 2012 18:22:07 GMT
And i forgot to mention but Argos were doing a cracking deal on the gazebo so decided that would act as a better cover than plastic sheeting which was like a greenhouse in the day and collected loads of condensation through the night. 2 days after reapplying the clay and i still have cracking but this appears much smaller than before and i have retained some extra clay to push back into the hairline cracks over the weekend. Does the cracking in the attached seem acceptable Thanks Attachments:
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Post by pete123 on Jun 29, 2012 20:19:45 GMT
...A mere flesh wound... check out my cracks... ukwoodfiredovenforum.proboards.com/index.cgi?board=pompeiiovens&action=display&thread=296&page=15although I had ground them out so they look worse than they were. I fired up my oven before I put the insulation on especially to see if they it would crack. I was then able to fill it easily. Mines opened up to about 3.5mm & you could look from the outside in. I guess you haven't got any cracks on the inside? In which case I doubt you have anything to worry about. Perhaps consider firing it up slowly a couple of times before the insulation goes on?
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Post by pete123 on Jun 29, 2012 20:23:18 GMT
...also I forgot to say what a great job you've done.
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jwyno
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Post by jwyno on Jun 30, 2012 9:34:06 GMT
Thanks Pete...its just good to have some reassurance to be honest.
Your whole build looks great - i would have loved to do a Pompeii but just wouldnt have the skills to know where to start.
The cracks in mine are only surface cracks as you have the modular concrete blocks underneath. I am hoping to start an initial drying out fire up tomorrow but will wait and see how dry the clay is looking first.
Thanks again for the confirmation, James
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Post by cannyfradock on Jun 30, 2012 12:21:50 GMT
James
Clay is always going to crack especially directly on top on refractory concrete. By adding a layer of clay.....I think you would have increased the thermal mass......but now you need (I think) a "thermal stop" to stop the dome acting as a heat sink. A layer (even 50mm) of vermecrete (vermiculite cement and water) would stop the heat seeping out and reflect it back into the dome.
If I were to improve the qualities of a modular oven I would probably use 25mm thermal blanket covered with vermiculite concrete using 2 x 100ltr bags.
The difference in my method and yours.....and nothing at all is merely how many extra small logs you need to chuck in for a pizza party. Extra insulation/mass will of coarse make a difference if you want to do a couple of batches of bread.
I am not saying that clay on top of refractory concrete is wrong....as I don't know how this will function....it can only enhance the workings of your oven. Have you asked Liam his opinion of your method?
Please let us know how you get on as the build itself is tip top.
Terry
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jwyno
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Post by jwyno on Jul 1, 2012 19:10:53 GMT
Thanks Terry
I think i will go with your suggestion and add the insulating layer of vermiculite. The modular oven basically comes as a kit, with the modular pieces of the dome being covered directly in clay and then immediately a final render layer.
I did ask Liam a while ago and he did agree that vermiculite would act as additional insulation so it sounds sensible to include this.
I have filled the cracks today, so if i can source the vermiculite/perlite from a local Jewsons, i will hopefully be able to continue mid week.
Cheers James
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Post by bookemdanno on Jul 1, 2012 20:36:59 GMT
Was Building sand used in the Fireclay mix? Cracking seems to keep cropping up, but i'm sure that if Sharp, Plastering or Concreting Sand were used it'd at least minimise this issue? I've not mixed a batch of clay, but i've always been under the impression that building sand is really only best used for up to half inch thick cement mortar beds, and then you should start adding amounts of sharp sand to strengthen the mix and add more bite. I tend to add a pinch for solid concrete blockwork, and would never lay slabs or even brick edgings on building sand.
My Tenpennth tho...
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jwyno
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Post by jwyno on Jul 2, 2012 16:02:26 GMT
The fireclay was just a pre-mix direct from Kilnlinings so i'm sorry but can't comment on the mix.
Being honest, the cracking I dont think is a major issue, as ultimately you have pretty solid refractory concrete which the clay insulates. Its more the fact this is the most involved I have ever been with any form of DIY and therefore want it to perfect, but also I was just unsure of the impact of cracks.
In regards the insulating blanket, I have calls out to Jewsons, Travis Perkins and the Build Centre but as yet they are all still looking. One suggestion was 'Rockwool' but this looks like it is more for limited fire prevention in homes and also has a foil backing.
Morgan Superwool was the other one that was found but they don't seem to supply it.
Can anyone suggest any other product names they may have used which you can just pick up as I would like to be able to drop in and collect so I can keep progressing with the build without needing to wait for a delivery.
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Tom B
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Post by Tom B on Jul 2, 2012 16:17:39 GMT
I got my body soluble ceramic blanket from Kiln Linings - 3000mm x 600mm and 50mm thick. That should be sufficient quantity for your oven. You may have to have it delivered, but it arrived for me very quickly.
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jwyno
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Post by jwyno on Jul 4, 2012 16:23:50 GMT
Thanks Tom.
I did get my oven from Kiln Linings originally but have found Sheffield Insulation/Kitson Thermal Supplies seem to have depots across the country so hope to be able to drop in to one of their locations and pick some up as they seem to have a range of similar insulation blankets available.
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jwyno
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Post by jwyno on Jul 5, 2012 21:29:59 GMT
I managed to book another day off as the weather was looking good and have really had a good day. I picked up the 25mm thermal blanket (Isofrax 1260) from Kitsons and had that in place by lunch and chicken wired up a couple of hours later. It wasnt perfect as i could feel a very small amount of movement under the blanket but nothing too serious or drastic so i was happy to run with it. Attachments:
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jwyno
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Post by jwyno on Jul 5, 2012 21:35:36 GMT
And then by about 8pm this evening i have the vermicrete in place as well mixed to a 6:1 mix. For this, i mixed it all by hand (which are very dry and sore now) by placing the Vermiculite is a mixing tray, then pouring in a small amount of water from a watering can with a fine rose head, and then adding in the dry cement a small amount at a time and giving it all a good mix and then repeating. It took about 15 minutes to mix 100litres but appears to be well coated...but i guess time will tell if its still all in place come the morning I have also added the final render to the back of the retaining wall but no photos of this area as there is nothing really to look at. Once dry though i will level off all the soil and have this area with easy to reach herbs so i can grab them and add them to my WFO recipes...yummy !!! Attachments:
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Post by cannyfradock on Jul 7, 2012 15:44:21 GMT
It looks like your getting there. You should have found that the vermiculite mix is quite solid when dry ......it will have a little give in it but the crust it forms can now be rendered/waterproofed.....if wanted.
Terry
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