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Terra cotta? To reclaim or throw it out?


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#1 Nelly

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Posted 17 February 2013 - 10:40 AM

Dear All,

I live in Ontario. This winter we have experience some very cold weather. While I keep my clay in a 60 degree room in a protected large Rubbermaid container with good moisture some of my terra cotta dried out?? I am not sure the reason for this problem. Due to my limited space, I have to keep my clay in the same room as my kiln. It is a good 15 feet away from the kiln spot. I am not sure what has happened that has made it react in this manner??

I tried to reclaim it by chopping it into small pieces, adding water and wedging. This was a three day process.

What I found when I went to throw it was that the harder sand particles came to the surface. It was not smooth in anyway. In fact, it was awful clay.

I called my supplier who said "yes, you can rewedge but it may be easier to purchase more clay." For him, it was a matter of my time.

So here are my questions:

1. Without a pugmill, can I really rewedge clay back to its original form (i.e., that that has either suffered from either cold or heat damage).

2. Is terra cotta a harder clay to get back to its original state? Does it have unique properties making my rewedging not work??

Thank you in advance for any replies.

Nellie

#2 OffCenter

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Posted 17 February 2013 - 11:52 AM

Dear All,

I live in Ontario. This winter we have experience some very cold weather. While I keep my clay in a 60 degree room in a protected large Rubbermaid container with good moisture some of my terra cotta dried out?? I am not sure the reason for this problem. Due to my limited space, I have to keep my clay in the same room as my kiln. It is a good 15 feet away from the kiln spot. I am not sure what has happened that has made it react in this manner??

I tried to reclaim it by chopping it into small pieces, adding water and wedging. This was a three day process.

What I found when I went to throw it was that the harder sand particles came to the surface. It was not smooth in anyway. In fact, it was awful clay.

I called my supplier who said "yes, you can rewedge but it may be easier to purchase more clay." For him, it was a matter of my time.

So here are my questions:

1. Without a pugmill, can I really rewedge clay back to its original form (i.e., that that has either suffered from either cold or heat damage).

2. Is terra cotta a harder clay to get back to its original state? Does it have unique properties making my rewedging not work??

Thank you in advance for any replies.

Nellie


1. Sure you can (unless it was damaged by heat but I'm pretty sure that didn't happen and freezing doesn't ruin clay), but your supplier is probably right about it not being worth the time and trouble. If you're saying that the clay you did reconstitute wasn't as good as the original then maybe a dash of ball clay, a sip of beer and a month or two of aging should fix that unless you somehow changed the ratio of components.

2. I don't think so.

Jim

E pur si muove.

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

#3 Nelly

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Posted 17 February 2013 - 01:36 PM


Dear All,

I live in Ontario. This winter we have experience some very cold weather. While I keep my clay in a 60 degree room in a protected large Rubbermaid container with good moisture some of my terra cotta dried out?? I am not sure the reason for this problem. Due to my limited space, I have to keep my clay in the same room as my kiln. It is a good 15 feet away from the kiln spot. I am not sure what has happened that has made it react in this manner??

I tried to reclaim it by chopping it into small pieces, adding water and wedging. This was a three day process.

What I found when I went to throw it was that the harder sand particles came to the surface. It was not smooth in anyway. In fact, it was awful clay.

I called my supplier who said "yes, you can rewedge but it may be easier to purchase more clay." For him, it was a matter of my time.

So here are my questions:

1. Without a pugmill, can I really rewedge clay back to its original form (i.e., that that has either suffered from either cold or heat damage).

2. Is terra cotta a harder clay to get back to its original state? Does it have unique properties making my rewedging not work??

Thank you in advance for any replies.

Nellie


1. Sure you can (unless it was damaged by heat but I'm pretty sure that didn't happen and freezing doesn't ruin clay), but your supplier is probably right about it not being worth the time and trouble. If you're saying that the clay you did reconstitute wasn't as good as the original then maybe a dash of ball clay, a sip of beer and a month or two of aging should fix that unless you somehow changed the ratio of components.

2. I don't think so.

Jim


Dear Jim,

Okay, so if I understand you correctly, you are saying, put it back in a bag and wait for while. Let it age. I have no problem in doing that. I will clearly label it as "trouble clay" and see how it works in a few months.

As for the ball clay thing, I hold no dry clay here at home. Is plain old talc powder considered ball clay?? I can definitely add that.

But as for your advice, I will do as you say. Sit and wait.

Just seemed really odd to have the clay particles come to the surface. Really frustrating when you are throwing. Even the slabs I tried to make had this grog-like stuff come to the surface.

But know I will take your advice, put in a dash of beer (I am guessing you meant in the clay and not in my body) and then start wedging again in a few months.

Will keep you posted.

Nellie

#4 OffCenter

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Posted 17 February 2013 - 03:20 PM



Dear All,

I live in Ontario. This winter we have experience some very cold weather. While I keep my clay in a 60 degree room in a protected large Rubbermaid container with good moisture some of my terra cotta dried out?? I am not sure the reason for this problem. Due to my limited space, I have to keep my clay in the same room as my kiln. It is a good 15 feet away from the kiln spot. I am not sure what has happened that has made it react in this manner??

I tried to reclaim it by chopping it into small pieces, adding water and wedging. This was a three day process.

What I found when I went to throw it was that the harder sand particles came to the surface. It was not smooth in anyway. In fact, it was awful clay.

I called my supplier who said "yes, you can rewedge but it may be easier to purchase more clay." For him, it was a matter of my time.

So here are my questions:

1. Without a pugmill, can I really rewedge clay back to its original form (i.e., that that has either suffered from either cold or heat damage).

2. Is terra cotta a harder clay to get back to its original state? Does it have unique properties making my rewedging not work??

Thank you in advance for any replies.

Nellie


1. Sure you can (unless it was damaged by heat but I'm pretty sure that didn't happen and freezing doesn't ruin clay), but your supplier is probably right about it not being worth the time and trouble. If you're saying that the clay you did reconstitute wasn't as good as the original then maybe a dash of ball clay, a sip of beer and a month or two of aging should fix that unless you somehow changed the ratio of components.

2. I don't think so.

Jim


Dear Jim,

Okay, so if I understand you correctly, you are saying, put it back in a bag and wait for while. Let it age. I have no problem in doing that. I will clearly label it as "trouble clay" and see how it works in a few months.

As for the ball clay thing, I hold no dry clay here at home. Is plain old talc powder considered ball clay?? I can definitely add that.

But as for your advice, I will do as you say. Sit and wait.

Just seemed really odd to have the clay particles come to the surface. Really frustrating when you are throwing. Even the slabs I tried to make had this grog-like stuff come to the surface.

But know I will take your advice, put in a dash of beer (I am guessing you meant in the clay and not in my body) and then start wedging again in a few months.

Will keep you posted.

Nellie


Nellie, don't add talc. It's not ball clay and the ball clay isn't important anyway. Just a little beer (in the clay, not you) may help but too much will cause it to stink. I don't know why the grog is coming to the surface on the reconstituted clay if it isn't doing the same on the original clay unless something you did in the process changed the ratio of grog to other ingredients like, for example, when you save pots that flop on the wheel what is lost is the really fine clay that is in the water, splash pan, and washed off your hands so that when you use the clay those pots were made out of it is not exactly the same clay that you wedged up to make them originally (the reason I suggest adding a little ball clay).... Anyway, I hope aging the clay a while helps.

Jim
E pur si muove.

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

#5 Nelly

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Posted 17 February 2013 - 05:20 PM




Dear All,

I live in Ontario. This winter we have experience some very cold weather. While I keep my clay in a 60 degree room in a protected large Rubbermaid container with good moisture some of my terra cotta dried out?? I am not sure the reason for this problem. Due to my limited space, I have to keep my clay in the same room as my kiln. It is a good 15 feet away from the kiln spot. I am not sure what has happened that has made it react in this manner??

I tried to reclaim it by chopping it into small pieces, adding water and wedging. This was a three day process.

What I found when I went to throw it was that the harder sand particles came to the surface. It was not smooth in anyway. In fact, it was awful clay.

I called my supplier who said "yes, you can rewedge but it may be easier to purchase more clay." For him, it was a matter of my time.

So here are my questions:

1. Without a pugmill, can I really rewedge clay back to its original form (i.e., that that has either suffered from either cold or heat damage).

2. Is terra cotta a harder clay to get back to its original state? Does it have unique properties making my rewedging not work??

Thank you in advance for any replies.

Nellie


1. Sure you can (unless it was damaged by heat but I'm pretty sure that didn't happen and freezing doesn't ruin clay), but your supplier is probably right about it not being worth the time and trouble. If you're saying that the clay you did reconstitute wasn't as good as the original then maybe a dash of ball clay, a sip of beer and a month or two of aging should fix that unless you somehow changed the ratio of components.

2. I don't think so.

Jim


Dear Jim,

Okay, so if I understand you correctly, you are saying, put it back in a bag and wait for while. Let it age. I have no problem in doing that. I will clearly label it as "trouble clay" and see how it works in a few months.

As for the ball clay thing, I hold no dry clay here at home. Is plain old talc powder considered ball clay?? I can definitely add that.

But as for your advice, I will do as you say. Sit and wait.

Just seemed really odd to have the clay particles come to the surface. Really frustrating when you are throwing. Even the slabs I tried to make had this grog-like stuff come to the surface.

But know I will take your advice, put in a dash of beer (I am guessing you meant in the clay and not in my body) and then start wedging again in a few months.

Will keep you posted.

Nellie


Nellie, don't add talc. It's not ball clay and the ball clay isn't important anyway. Just a little beer (in the clay, not you) may help but too much will cause it to stink. I don't know why the grog is coming to the surface on the reconstituted clay if it isn't doing the same on the original clay unless something you did in the process changed the ratio of grog to other ingredients like, for example, when you save pots that flop on the wheel what is lost is the really fine clay that is in the water, splash pan, and washed off your hands so that when you use the clay those pots were made out of it is not exactly the same clay that you wedged up to make them originally (the reason I suggest adding a little ball clay).... Anyway, I hope aging the clay a while helps.

Jim


Dear Jim,

Okay, what about this?? If while I have my bags in the rubbermaid container and I notice that it is starting to get a little harder than I like, I fill it with about 1/2 cup of water in the bag. Would this change the grog ratio?? I am doing nothing else. Zero. But if you think this is something I am doing wrong (i.e., adding the water to the bags) please, please let me know. I have a huge container of clay and I just hope this isn't what the whole lot will be like. I am guessing the beer is like vinegar to assist in the aging process. I will buy one bottle tomorrow and see how it goes.

Thank you Jim for everything. It is just odd that the clay is not reclaiming as my usual stuff does and the sad part is, I haven't even used it yet??

Nelly

#6 bciskepottery

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Posted 17 February 2013 - 07:23 PM

You might want to consider adding some moisture inside the rubbermaid container . . . here is a video from Tim See that shows how he does it.

#7 Diane Puckett

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Posted 17 February 2013 - 08:01 PM

I have not tried it, but I have heard several people say they put the bag of clay in a bucket of water. No water directly into the bag. The idea is that, if clay in a bag can dry out, it can also absorb moisture,
Diane Puckett
Dry Ridge Pottery

#8 Nelly

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Posted 17 February 2013 - 08:05 PM

I have not tried it, but I have heard several people say they put the bag of clay in a bucket of water. No water directly into the bag. The idea is that, if clay in a bag can dry out, it can also absorb moisture,


Dear Diane,

I have also heard this. It is kind of like outward pressure on the bag somehow allowing some sort of absorption to take place despite the plastic barrier?? Surface tension?? I am not sure but like you I have heard this.

I will wait and see how my next bag of clay opens and decide how to proceed with winter storage. It maybe that I go with this plaster base slightly dampened from time to time.

Nelly

#9 nairda

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Posted 17 February 2013 - 08:38 PM

I've had good luck softening clay that has sat in the bag for too long like this:


1) Make sure the plastic bag containing the clay has no holes in it.
2) Put the bag of clay in a 5 gallon plastic bucket, standing the bag of clay upright.
3) Pour anywhere from 1/2 to a 1 cup of water inside the bag of clay, pulling the plastic away from the sides of the clay in the bag so the water is touching the clay on all sides.
4) Add water to the bucket, all the way to the top of the clay in the bag, but not so high that this water gets inside the bag.
5) Put the lid on the 5 gallon bucket. Check the clay every few days. Keep adding small amounts of water inside the bag until the clay is as soft as you want.

The pressure of the water pushing against the outside of the bag pushes the water that you poured inside the bag into the block of clay. I've had clay that was almost too hard to throw easily return to a softness level perfect for throwing plates. Took it about 2 weeks and it did not need much wedging - wetness was fairly uniform.

#10 Nelly

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Posted 17 February 2013 - 09:31 PM

I've had good luck softening clay that has sat in the bag for too long like this:


1) Make sure the plastic bag containing the clay has no holes in it.
2) Put the bag of clay in a 5 gallon plastic bucket, standing the bag of clay upright.
3) Pour anywhere from 1/2 to a 1 cup of water inside the bag of clay, pulling the plastic away from the sides of the clay in the bag so the water is touching the clay on all sides.
4) Add water to the bucket, all the way to the top of the clay in the bag, but not so high that this water gets inside the bag.
5) Put the lid on the 5 gallon bucket. Check the clay every few days. Keep adding small amounts of water inside the bag until the clay is as soft as you want.

The pressure of the water pushing against the outside of the bag pushes the water that you poured inside the bag into the block of clay. I've had clay that was almost too hard to throw easily return to a softness level perfect for throwing plates. Took it about 2 weeks and it did not need much wedging - wetness was fairly uniform.


Dear Nairda,

I can definitely do this with some others I have that may have come to that consistency. I don't mind the two week wait time. It is interesting how this process works. It would seem that the clay draws water somehow from the outside in?? I am guessing it absorbs only as much as it needs to stay moist--almost like a plant with its roots reaching out?? I will look at my bags tomorrow to see if there are any that are close to this state. Right now, I am dealing with some that are just starting to reach this hard to indent through the bag stage. But I will definitely remember these instructions. I have a good size pail from home depot that will work well. Thank you so much for these instructions as well.

You got to love this forum!!!

Nelly

#11 perkolator

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Posted 19 February 2013 - 04:15 PM

no matter how well-aged or plastic your clay body is, when it dries out you usually lose all of it and have to start over when your reconstitute it. this is most likely what happened to you.

for immediate plasticity in clay i believe the go-to's are vinegar or epsom salts solution, which act as a flocculant and changes the acidity. aged clay usually gets more acidic/plastic with time since bacteria = acidic waste.

#12 Nelly

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Posted 19 February 2013 - 04:39 PM

no matter how well-aged or plastic your clay body is, when it dries out you usually lose all of it and have to start over when your reconstitute it. this is most likely what happened to you.

for immediate plasticity in clay i believe the go-to's are vinegar or epsom salts solution, which act as a flocculant and changes the acidity. aged clay usually gets more acidic/plastic with time since bacteria = acidic waste.


Dear Perkolator,

I have approximately a bucket full of scraps from this bag drying. I will add some "mother" vinegar when I start over again and slake this bag. Thank you for the tip with epsom salts.

Nelly

#13 Essaily

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Posted 19 February 2013 - 04:55 PM

Hi noticed your interesting clay question,
presently I'm cleaning clay and sieving out the sand,
and using a fine screenprinting mesh to separate the sand from a thin,
runny slip.

I dry it in towels in bucket, the Japanese potters use this method,
rather than plaster bats, which always seem to get stuck to the clay!

I think its worth recycling your terracotta, vinegar and
epsom salt also works for me too - no smell.




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