watering dry clay

Pardon my ignorance but I bought some fire clay and it is in dry powdered form. Do I just add water and start stirring? Any idea of weight of water to weight of clay? My application is to seal a metal box that will be used for case hardening in order to keep air out.

Thanks in advance,

Wes

Reply to
Wes
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Wow, I can't even imagine how that would work...

What you want to do is put the dry clay in a burlap bag (plastic burlap is ideal but I have also been told that a leg cut off of an old pair of levis also works well), tie it off, them put this bag in a 5 gallon size bucket (or anything large enough to immerse the bag in water) and fill with water. You would want the clay in the bag to take up no more than 3/4 of the volume of the bucket. You are going to have more water in the bucket than you will want in the clay but that is ok. It will thoroughly saturate the clay (let it sit overnight). Tie the bag off with a rope and hang it outside over a strong tree limb or the like where it can drain off the excess water. When it has dried enough to be workable (you should be able to stick your finger in it without your finger coming out muddy but it should still be soft enough that you can easily put a dent in it), unroll the bag from the clay.

REMEMBER TO WEAR A MASK! Clay has silica in it and this can damage your lungs. It is best if you do this outside and if you try to work slowly so you keep the dust in the air to a minimum.

Reply to
DKat

You pack a low-carbon steel object you want to case-harden in powdered carbon (mixed with other stuff) in a metal box, and seal it with fire clay. Then you stick it in a kiln and soak it for a few hours/days - the carbon infuses the surface of the object, giving the outer layer a higher carbon content which can subsequently be heat treated to make it hard, while the inner low-carbon steel remains tough. Easy. :-)

Reply to
Rob Morley

That is why I bought a pottery kiln at an auction. I might try pottery with it some day. What is a good clay for a crucible? :)

Wes

Reply to
Wes

Porcelain

Reply to
DKat

Another responder addressed that one. Thanks to poster.

I'll try the leg from the denim jeans method and store the mix in a mason jar to keep the water in.

Oh I'll have a mask, especially since part of the heat treat mix contains barium carbonate. Wished I had known I could get that at Baileys with my clay order, I bought the barium carbonate at skylighter.com .

I'm going to do all my mixing outside, usually there is a nice west breeze. I do want to collect on my SSI payments.

Thanks again,

Wes

Reply to
Wes

Oh Hell! If you are just making up a cup or so DON'T follow my instructions! Sorry - a potter would never make up that little clay. You could modify what I said and just use an old sock. The thing is, you want your clay saturated but you also want it drained to the right consistency. Since you are not going to have a clay mixer the easiest way it to do as I said, but on a small scale. Sorry, I had no idea what you were aiming for.

Reply to
DKat

Fire clay heavily grogged with mullite or other pre-fired refractory will make a decent crucible. This is basically what fire bricks are made from.

Porcelain might work for low temperature work but is not the best for melting metals.

For melting metals like bronze or even iron, crucibles are usually made from fire clay and graphite. This stuff takes thermal shock well and withstands the corrosive action of molten metals.

What is the crucible for?

Reply to
Bob Eld

I am intrigued by Donna's approach of putting the dry clay in the pants leg and then immersing it. I will probably give it a try the next time I mix clay. (Thanks, Donna!) However, this is the first I have heard of that.

So, just for the record, in the traditional method you start with a container of water and pour powdered clay into it. Exact amounts don't matter here, as you want to have excess water. The clay will settle out and after a few days you can pour or siphon most of the excess water off, leaving a clay slop. That's when (some of us, anyway!) pour it into the pants leg and hang it. The traditional method was to pour it out onto a plaster or concrete slab and keep working it to let the slab absorb the excess water until the clay was the desired consistency, but that is cumbersome and (if you use plaster) risks contamination by plaster fragments. But it is quicker than waiting for the leg to dry naturally.

But since you only want a jar full, you can probably pour the slop into a sock as Donna suggests. You may not even have to let it settle too much first. The sock will dry that small amount of clay much faster, probably less than a day. (Especially since you probably want a pretty soft clay for sealing purposes.)

I would have worried that the dry soak method would leave lumps or something, but I never gave it great thought since I never heard of anyone doing it that way. Encouraged by Donna's success, I'll have to do some experiments!

Best regards,

Bob Masta DAQARTA v3.50 Data AcQuisition And Real-Time Analysis

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Reply to
Bob Masta

Just to let you know, I have never used a levi pants leg so I don't know how well they drain. It was used by another poster who seemed to find them ideal. I have plastic burlap bags that are about the same size of a five gallon bucket but longer. I cannot remember where I got them in the first place but they strike me as what you would get grass seed or grain in. They are perfect for doing this IMO because they don't rot and drain well, yet keeps the clay uniform in how wet/dry it is - I'm sure that if you let it get too dry it would dry from the outside in but I have never had that happen. I do have to wedge up the clay but that is true for any clay I have ever had. One of the things that makes this such a great way to recycle clay is that you don't have a bucket or pan that you have to try and scape mud out of. When the clay is the right dry/wet consistency, the bag just peels right off of it. It works best (as does any recycling) if the clay is completely dry and broken into small pieces before immersing in water. I have been recyling clay since day one and have done it in many different ways. None tops this one.

Donna

Reply to
DKat

Your sock suggestion is excellent for my current needs. Since my heat treat oven is a pottery kiln, maybe I'll get to use your levi leg suggestion at a future point for watering clay for actually making pottery.

My hobby is machining, where we often turn things and cut away stuff. It might be fun to spin a lump of clay and shape it into something.

What rpm range do potters wheels turn at?

I do thank you for your advice,

Wes

Reply to
Wes

My wheel does 0-250 RPM - however there is wide variance in how fast people turn their wheels when they throw. I have seen people work at such slow speeds that it makes me grit my teeth - others can go full speed from start to finish.

I'm having a hard time imagining lathing a piece of clay although some parts of throwing can be very much like that. You might be able to do that if the clay was leather hard... Don't know, could be interesting. Let us know if you succeed!

Donna

Reply to
DKat

Oh no, I'd build a conventional wheel and do it the traditional way. FWIW, ceramic inserts used in lathes for turning are very effective.

Thanks,

Wes

Reply to
Wes

I don't have space in my workshop for a big plaster slab, so I use a similar method.

Mesh paper-baskets are the big clue in my system. I line a paper-basket with one of hubby's old cotton shirts or a piece of cotton bed-linen. Put the basket into a plastic waste basket that is a tad larger, dump in the dry clay and pour water well over the top. Fold the shirt over the clay and let sit for a few days.

Then I take the mesh basket out and put it on a couple of pieces of wood inside a water-proof plastic box. As the days go on, I poke the clay through the cloth to see how it is coming along and wedge it when it has reached a good consistency.

I used to hang the clay up in bedclothes to drip off, but A) the material wasn't strong enough to be reused and B) it took space in my teeny workshop. So - with this waste-paper basket system, I can just shove the container under my shelves and still get the job done. And less work intesive than the plaster slab system as well.

Marianne

Reply to
Bubbles_

Marianne and Donna:

Does this method work equally well for new powdered clay and for reclaimed scraps? (Not in the same batch.)

Thanks!

Bob Masta DAQARTA v3.50 Data AcQuisition And Real-Time Analysis

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Reply to
Bob Masta

I have only used it to reclaim clay but since I bone dry my clay and break it down to as small of pieces as I can, it should be comparable - If you are mixing clays (dry materials - i.e. 40% fireclay, 20% EPK 40% Ballcly), IMO you should make a slurry first. If you are using plastic burlap like I am, I could imagine doing this inside the bag which is in the bucket, letting the clay settle, then pulling the bag out of the bucket to drain. If you are doing it in something like a levi pant leg, I would make the slurry and then pour this into the pant leg (leg in bucket) and then pull the leg out and let drain. Dozens of ways to skin a cat and I am just imagining what I would do in this case.

Donna

Reply to
DKat

To be honest, Bob, I have never made "fresh" clay, but I would think the method would work OK, as you have the cotton lining the mesh inside the plastic, so not much room for flow or movement of water, really. I am not sure if you add the powder to the water or vice versa. I would be tempted to add powder to water in that case, as I imagine it might otherwise lump itself at the bottom and take longer to absorb the water right through.

I use the method for all my clay reclaiming, and I am very pleased with it. I try to do as Donna and make my clay as little as possible - though I tend to just squish the bits thin before putting them in the reclaiming buckets to dry. I actually think I have better results NOT breaking into tiny pieces, as then there is better water flow between the pieces, but I can't say 100%, because I just let that clay sit in the water for days on end! It being under the shelf, I sometimes just forget about it! Must remember the one I have had drying before I go on holidays, though!

Hope that answers your query. Best thing is just to try it out on a smaller scale and see what happens. Worst case, redry the clay and then retry.

Oh yes - and I would DEFINITELY mix the powdered ingredients very well before mixing with water. But you knew that already, right? ;-)

Marianne

Reply to
Bubbles_

I've always added powdered clay to water in the "traditional" way, then let it settle a few days and remove the clear water before pouring the slurry into the pant leg (which may become the new "traditional" way of drying, instead of plaster bats). But I'm always open to new ideas. Based upon your advice, I'll probably keep doing it this way for new clay, and save your method for reclaim. On the other hand, maybe I'll do a small-scale experiment with your method on new clay, next time I make up a batch.

Thanks, to you and Marianne, for sharing new ideas!

Bob Masta DAQARTA v3.50 Data AcQuisition And Real-Time Analysis

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Reply to
Bob Masta

[Ir doesn't sound like this will work too well, Wes. Clay shrinks considerably as it dries, while the metal will expand as it gets hot. The clay won't adhere, and will break up and flake off, making a mess. Can't you make your metal box seal itself, with bolts? A refractory gasket of some sort would help; look for ceramic fiber in rope form, or a piece of refractory sheet material. Here's a link to some of that:
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.]Andrew Werby
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Reply to
Andrew Werby

New and old, sharing is the most important part, don't you think?

Anyway - I must add a PS to my previous posts. You might want to turn the paper-bin out after a while, so the water goes the other way through the clay and makes it more homogenously the same softness. I forgot to do one of mine last week, caught up with it this week and it was squishy down bottom and pretty hard up top. Took quite a bit more muscle to wedge, for sure!

Again - enjoy your weekend!

Marianne

PS - mentioned the cone discussion to my teacher, and used the words "you must do such-and-such" (translating to German is not my forte), and she just looked at me and said "anyone who uses the word _must_ in connection with pottery....." and the look said the rest! LOL! Think she has a point?

Reply to
Bubbles_

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