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Clay Firmness


Dave K

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I am looking for opinions. I buy my clay from a local supplier and usually get Standard 240. I picked some today that was dated 3/16/16. I opened one of the boxes and it was very hard. I cut up the block into 3-4 pound pieces and put it in a plastic container, cover it with a wet towel and put a lid on the container. In time it will be usable.  I have had this problem in the past and sometimes returned it to the supplier. Am I expecting too much for workable clay out of the box or is clay just a product that is unpredictable on it's consistency?

 

Thanks for your comments.

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I truly think it's one of the down sides to using pre mixed clay is that you never know how dry it will be coming out of the box.

I truly think the down side of mixing your own clay is that you never know how dry your clay is when it comes out of storage.

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Guest JBaymore

I have found that the plastic bags that the suppliers have switched to of late are really gas permeable to water vapor.  SO year old clay, which used to be something you really wanted and jumped up and down about... is no longer an asset.  It dries out too much right thru the bag and gets really hard.  Cheap bags.

 

I have some clay stock in bags that is about 20 year old (special stuff I use in limited quantities) that is absolutely as damp as it was when it was brand new.  But .....ummmmmm..... is it nice to work with now.

 

I have clay here now that is only a year old...... that I have to totally re-constitute.  Hard as a rock.  HATE this.  I have a batch mixer.... but it is a pain in the butt.  And labor time.

 

best,

 

......................john

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Standard has been mixing the 240 rather stiff this past year. The 630 has been rather soft. The 365  and 112 has been perfect. You just never know. There are a lot of variables at work in clay mixing, and the guys doing the mixing are just hourly labor, so a little stiff or a little soft isn't something they know much about. It's a management problem. Their tech should be keeping a closer eye on it. Give them a call and let them know. They're more likely to get it right if they have complaints.

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I need to write Highwater and tell them how much I enjoyed batch # so and so on red rock. It was by far the best clay I have dealt with from them. 

 

I used a local clay company here in Georgia for some clay.  I didn't end up liking the clay fired, but it was so soft because I guess it was made locally and hadn't sat in a warehouse forever. Like John said I have some bags I haven't ever opened of some porcelains and they are ROCK hard. Then I have some bags from another company with higher quality bags and they are just as soft as they were the day I opened the box and the other bag. I would pay more for a better bag all day long.

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Guest JBaymore

Like John said I have some bags I haven't ever opened of some porcelains and they are ROCK hard. Then I have some bags from another company with higher quality bags and they are just as soft as they were the day I opened the box and the other bag. I would pay more for a better bag all day long.

 

Bingo! 

 

best,

 

.....................john

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You really should find a method of figuring out if the clay is too stiff or too wet to throw the vessel you want. My method is to first to see if the clay will wedge. Then I pull à wire tool thru the unit of clay. If I have to use my thumbs to hold the clay back, then the clay is too stiff/dry,, and water needs to be added, until the wire tool can pass thru on its own.

 

The heighth and form really determines how stiff or wet the clay should be.

 

See ya ,

Alabamà

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Soft clay is much easier to work with, How hard the clay is mostly a matter of preference and how physically strong you are. The more strength you have the dryer the clay you can throw and I think the dryer the better. I've watched Claudio Reginato throw soldate 60 that was as hard as a brick and had been left out of the plastic bag for days drying out in preparation for a throwing workshop and it was still a little soft for his style. But he is incredibly strong from 40 years of throwing 8 hours a day 7 days a week and can handle it, he also uses a special style of wedging to get the clay ready. Normal wedging techniques don't work very well when the clay is very very hard and he uses a technique of slicing the clay, rolling a curve and then slaps the sections back together.

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Agree with Matthew...I drop all bags of new clay from about 3 ft off the floor onto a concrete surface.  I do each side once.  The clay is  much softer after this procedure.  Probably not enough to fix a truly hard bag, but I can feel the difference on bags that seem hard to the touch.

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When I get a bag of clay that is too hard, I just take some of the older softer clay from trim scraps that have been sitting around and "bread slice shuffle" them together. I turn this a couple of times cutting and slamming. Reshape it into two blocks and have 50# of good clay in a few days after spraying with a little water and placing in clay bag. Standard has dropped ties on bags several years ago-can be ordered for cost. However, I have been able to use the bags of clay after two years of storage outdoors under a tarp. In PA the clay does freeze and thaw a bit, but for some reason or other it is better for me after I re-wedge it out of the bag after a year than when fresh. I am not very big, or strong, but I like may clay quite stiff for jars, mugs and bowls. For plates always softer.

 

best,

Pres

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You can always you the 5gal barrel method, put 4 ounces of water in the bag and tie it up.  Put it in the 5gal bucket and fill it with water, the water pressure will force that moisture into the clay.  I have rejuvenated some pretty dry clay this way.   Denice

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Guest JBaymore

You can always you the 5gal barrel method, put 4 ounces of water in the bag and tie it up.  Put it in the 5gal bucket and fill it with water, the water pressure will force that moisture into the clay.  I have rejuvenated some pretty dry clay this way.   Denice

 

I think the permeability of the cheap bags to the water molecules is also a factor here.  Try just putting the clay in the bucket of water without any water added inside the bag.  Leave it immersed the same amount of time you would otherwise.  Bet it is softer too.

 

best,

 

.................john

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I am not a production potter and thus do not use a lot of clay per month.  However, as I use the second bag of clay in the box, I open the next box, check the condition of the clay and add water as (i think) needed.  By the time I get to the new box, the clay is ready to use.  I do not take it out of the box to add water.  I use Standard's clays and wish they used twist ties.  I twist the bag top and push it between the clay and the box.  Thus I do not need a 5-gallon bucket, the box does the job of holding the water against the clay. This method has worked for me for 40 plus years.  Donna

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The poor mans method is put some clay in a container with wet towels and cover. Stoneware clay work best -Porcelain not so much.

The upside of having say a peter puger is you can make that clay soft very quick and easy by adding a bit of water while re-pugging it.

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We go through about 500#'s a month of Standard 105 that is purchased in 1000# lots. The last 500#s is stored in a VERY hot metal box (the best way I can describe it) but the humidity is pretty high in there too. (small roof leak when it rains hard).  The remaining 500#s was still usable as-is. The Laguna clays that we keep in there longer we haven't had a problem with drying out either. The short version is: we live in a very humid area and don't have that problem. For everything else we have Peter.

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