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inclusions in slabs


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#1 Glen Peters

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Posted 03 April 2013 - 09:31 AM

Hello

I want to press items into slabs but I can see it causing cracks?

What can I do to avoid that?

I thought of using strands of fiberglass to reinforce the edges where the cracks are likely to form but there's probably a better way?

Thanks

#2 justanassembler

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Posted 03 April 2013 - 01:10 PM

Hello

I want to press items into slabs but I can see it causing cracks?

What can I do to avoid that?

I thought of using strands of fiberglass to reinforce the edges where the cracks are likely to form but there's probably a better way?

Thanks


what exactly are you using as an inclusion? Your cracking issues are not really structural in the sense that they need reinforcement so much as you need to reduce the shrinkage of your clay to match the shrinkage/expansion of your inclusion more closely...

#3 Glen Peters

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Posted 03 April 2013 - 01:29 PM


Hello

I want to press items into slabs but I can see it causing cracks?

What can I do to avoid that?

I thought of using strands of fiberglass to reinforce the edges where the cracks are likely to form but there's probably a better way?

Thanks


what exactly are you using as an inclusion? Your cracking issues are not really structural in the sense that they need reinforcement so much as you need to reduce the shrinkage of your clay to match the shrinkage/expansion of your inclusion more closely...


Hi justanassembler

I'm thinking of all sorts of items but for this instance I'll say a few sprigs of asparagus in an 8"x 8" tile say 3/8" thick. I haven't done anything like this in 20+ years so I'm a bit rusty and I recall having difficulty back then with inclusions. Even if they were removed while the clay was still moist? Back then I would wrap the edges in plastic wrap to slow its moisture loss but I still had problems.

#4 Chris Campbell

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Posted 03 April 2013 - 04:22 PM

Very soft clay and old, tough asparagus!
I have had the best success with inclusion patterns when I used very soft clay and got the inclusions out before it started to dry too much .... You have to find the perfect time to pull them off so the pattern stays but the clay does not crack. You cannot leave them in most of the time because they don't shrink as much as your clay will. The only exception I found was macaroni which swells then dries nicely at the same rate as the clay.

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#5 AtomicAxe

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Posted 03 April 2013 - 09:54 PM

Have you thought about using paper clay? It might be an option since the whole idea behind paper fiber in the clay is to help reinforce the clay before firing bisque to reduce cracking in a clay body. Also, if you are using an item to only temporarily stay in the clay, why not use a plaster mold of the item? In that way, you can let it absorb some of the liquid out of the clay helping it hold the pattern better, as well as have an ideal source of your impression. Asparagus is pretty large so you can make a good mold of it no problem.

#6 Glen Peters

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Posted 04 April 2013 - 05:52 AM

Have you thought about using paper clay? It might be an option since the whole idea behind paper fiber in the clay is to help reinforce the clay before firing bisque to reduce cracking in a clay body. Also, if you are using an item to only temporarily stay in the clay, why not use a plaster mold of the item? In that way, you can let it absorb some of the liquid out of the clay helping it hold the pattern better, as well as have an ideal source of your impression. Asparagus is pretty large so you can make a good mold of it no problem.


Thanks AtomicAxe I wondered about paper clay, I'll have to try some. And, I like the idea of the plaster cast for later.

#7 Glen Peters

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Posted 04 April 2013 - 06:38 AM

Very soft clay and old, tough asparagus!
I have had the best success with inclusion patterns when I used very soft clay and got the inclusions out before it started to dry too much .... You have to find the perfect time to pull them off so the pattern stays but the clay does not crack. You cannot leave them in most of the time because they don't shrink as much as your clay will. The only exception I found was macaroni which swells then dries nicely at the same rate as the clay.


Hi Chris

I know about macaroni --I did some experiments with pasta and dried bread many years ago, it looked awful --as it dried it got all moldy but after firing it looked great! Moist wood chips work to and don't mold up.

Thanks for your moist clay advice but it brings up another question; how do you add moisture... without a pugmill?

#8 Chris Campbell

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Posted 04 April 2013 - 09:42 AM

How to add moisture without a pug mill?

Here's my lazy potter's answer.
Open the clay bag, add a wet towel and push it down the sides as far as you can. Tie it closed. Let it sit for a day or two.

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#9 OffCenter

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Posted 04 April 2013 - 09:55 AM

How to add moisture without a pug mill?

Here's my lazy potter's answer.
Open the clay bag, add a wet towel and push it down the sides as far as you can. Tie it closed. Let it sit for a day or two.


another way that is quicker but lots more work is to make a small amount of clay very wet by putting a fistfull in water then work it until the water is worked in then do it over until you have a fistfull of sloppy wet clay then do that again and again then cut the hard clay into slabs and put the sloppy wet clay on each slab then put together and wedge. Like I said, lots of work but worth it for making up to a 25 lb bag of clay softer quickly.

Jim
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#10 Claypple

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Posted 04 April 2013 - 10:12 AM

Fool-proved method: Place it on the wheel and "play" with it using a lot of water. Make a cylinder, a bowl, etc, then "crash and cramble" it.
It will have much more moister.

#11 Glen Peters

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Posted 04 April 2013 - 10:58 AM

Thanks Chris and Jim I'll try both those methods. There is lots of old stiff clay around here...

#12 Glen Peters

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Posted 04 April 2013 - 11:16 AM

Fool-proved method: Place it on the wheel and "play" with it using a lot of water. Make a cylinder, a bowl, etc, then "crash and cramble" it.
It will have much more moister.


Thanks Claypple but I don't have a wheel... I get what your saying though and will have to use a poor potters alternative

#13 Chris Campbell

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Posted 04 April 2013 - 02:59 PM

>>another way that is quicker but lots more work is to make a small amount of clay very wet by putting a fistfull in water then work it until the water is worked in then do it over until you have a fistfull of sloppy wet clay then do that again and again then cut the hard clay into slabs and put the sloppy wet clay on each slab then put together and wedge. Like I said, lots of work but worth it for making up to a 25 lb bag of clay softer quickly.

Good Grief!!!
That has got to be the MOST difficult way I have ever heard of to soften clay ... you gotta get lazier Jim!!Posted Image

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#14 OffCenter

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Posted 04 April 2013 - 05:13 PM

>>another way that is quicker but lots more work is to make a small amount of clay very wet by putting a fistfull in water then work it until the water is worked in then do it over until you have a fistfull of sloppy wet clay then do that again and again then cut the hard clay into slabs and put the sloppy wet clay on each slab then put together and wedge. Like I said, lots of work but worth it for making up to a 25 lb bag of clay softer quickly.

Good Grief!!!
That has got to be the MOST difficult way I have ever heard of to soften clay ... you gotta get lazier Jim!!Posted Image


It's not all that hard. I'm assuming the situation is that you only have hard clay and you need to soften up some for immediate use. (All the clay I ever see is way too soft in the bag so I have to dry it out before use.) But, if I was down to my last bag of clay and it was too hard, I'd sure rather take a half hour making it softer my way than wait a few days for towels to soften it up. Actually, Claypple suggested something easier than my suggestion and a lot faster than your suggestion.

Jim
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"But it does move," said Galileo under his breath.

#15 Glen Peters

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Posted 04 April 2013 - 06:13 PM

I think I'll try to find a used pugmill, all this talk of wedging is making these old arthritic wrists sore! In the meantime ill have to use one of these suggestions

Thanks All




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