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Post by patamos on Sept 26, 2020 12:26:28 GMT -8
I'm thinking of using dogwood , its abundant here & straw is available free or cheap - a big bale , you know one of those monster things costs 5 € In the UK Hazel was traditionally used & it grows here a few miles away but i'm keen to just use what's around me , experiment , fail and learn , work things out.I made a small amount of slip to cast the top slab of my oven , broke it up by hand so any tips would be welcome . I don't have a cement mixer , i do all my mixing by hand as most of our construction is dry wall stone or timber but i'm not a primitive ! For larger volumes of light clay there are a few ways to mix. I have an old mortar mixer that modified paddles/blades this works for shorter length fibre such as wood chips, hemp hurds and any plant stalks under 2" long. For longer straw/fibre better to use a tumbler for smaller volumes i sometimes mix (shortfibre) in a horse feed bucket with a drill and egg-beater bit. to mix light clay without machinery have 3 people face towards each other with pitchforks and take turns 'tossing the salad' For mixing clay slip I have a good drill and harness set up in a barrel. I will post pictures soon.
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Sept 27, 2020 8:37:10 GMT -8
yeah i was thinking of investing in a paddle mixer but i was more interested in tips on how to make the slip.The clay i dug for the last batch was semi dry so i broke it down to a fairly fine powder before mixing with water. "For mixing clay slip I have a good drill and harness set up in a barrel" is this with dry clay powder or can you use the semi dry lumps that you dig up ? it would be great to see the pictures
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Post by wrekinwanderer on Oct 2, 2020 0:56:13 GMT -8
Hi Pat,
Lovely to see your beautiful work on the website - thanks for sharing!
I have a question for you. Do you use clay throughout for your benches or do you use a brick front wall and then shape a clay render over the top?
Best wishes,
Mike
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Post by patamos on Oct 13, 2020 20:01:34 GMT -8
Thanks Guys My drill in harness in barrel set up has served me well for many years now. I just took pictures for someone asking about it so i will see about posting them soon. Yes it can mix anything from dry clay to sludge to hard clumps. ALthough with the latter it is always good to let them soak in the barrel (about 60% full of water) for a day or two. Mike, i tend to build with old clay bricks and fiber-less cob mortar. Then a layer overlapping sheets of 4.5oz fiberglass mesh (often used in EIFS concrete mortar application) over the outer surfaces. This gives a durable yet resilient structure that IMHO is better than double wall (refractory core with separate brick/stone facing) or single wall (old school clay brick and mortar). It would most accurately be described as 'double-skin' but this term is commonly used interchangeably for double wall masonry heaters. I've built a lot of cobb and light clay houses/cabins/studios... but not so many pure cob heaters. Somethings about the old clay-bricks, the feel, the versatility in shapes and volumes impels me to keep working with them. That said, I also tend to follow some sound advice from long-time builder Lars Hellbro: 'Above 500c use firebrick. Once below 500c any clay brick will do'. And also from Norbert Senf: 'Refractory materials lining the first 4 or 5 feet downstream from the fire chamber. After that any clay brick.' So the question then is: What areas of the heater are going to experience over 500c under the craziest over-firing scenarios (eg winter earthquake or ice-storm... running 24 - 7...)? Tall narrow ones will accumulate more concentrated heat than long stretched out benches...
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Oct 14, 2020 1:53:59 GMT -8
"it is always good to let them soak in the barrel (about 60% full of water) for a day or two" yeah i did this a week ago in a glass jar to check the sand & organic content of a new vein of clay we dug up - it's almost all clay 5cm & about 3 mm of sand
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Post by patamos on Oct 25, 2020 9:39:25 GMT -8
"it is always good to let them soak in the barrel (about 60% full of water) for a day or two" yeah i did this a week ago in a glass jar to check the sand & organic content of a new vein of clay we dug up - it's almost all clay 5cm & about 3 mm of sand Ya then best to figure out how much silt. swooshing a bit between your teeth can be an indicator. A bit of grit okay. Lots of grit may be a problem...
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Oct 25, 2020 12:30:17 GMT -8
HAHAHAH. OK Pat i'll take it as read .Just rubbing the slip between my fingers told me what i want to know .Soaking and then pouring off the excess water left a slip that combined perfectly with 2 parts sand. I did some repairs on the oven with the mix & it's all good.iv'e worked in construction on and off for 20 + years , mostly with NHL mortars , stone & traditional building but i have to say that the clay/sand mortar has been a revelation.
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Post by patamos on Oct 31, 2020 11:27:07 GMT -8
Ya clay is such an interesting material. And then there are so many different types of clay. For many years i used lincoln fire clay in my light coloured finish plasters, and as mortar in fairly hot sections of heaters. But compared to the brown clay that comes out of the ground where i live Lincoln is way less sticky and more crumbly.
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