Tuesday, March 14, 2006

Tech Support Moist Clays

Moist Clay issues: Post your Question here.

12 Comments:

Anonymous Anonymous said...

Hello. I was wondering if most clays and glazes can be used to make tiles for a walk-in shower. I love the look of the Spectrum Low Stone and the Amaco Potter's Choice glazes. I've made some tiles with Sheffield's slip and a mold and am wondering if those are suitable for a shower, or if I need to use another kind of clay. Thank you!

11:12 AM  
Blogger tjhspi said...

Hi, We recommend the T6B clay which is a cone 6 for tile making. Another good altermative if you can fire to cone 10 is the T1S. Either way just make sure you fire it to that cone to fully vitrify the tiles otherwise they may be subject to water absorbtion.
For a glaze the potter's choice are nice for a cone 6, I like those also. The spectrum Low Stone glazes are nice but too low fire for either of these bodies.
Also stay away from any crackle glazes as they are not water tight.
Hope this is helpful
TJH

12:31 PM  
Anonymous Anonymous said...

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10:55 AM  
Anonymous Anonymous said...

hi, I have recently found a small clay supply at the back of my property which after minor screening for sticks fires nicely to cone6. i am currently working with it to produce a cone 10 clay for wood-firing. my question is how long should i let a pugged clay sit before throwing with it or does it need to age at all?
thank-you

1:39 PM  
Blogger tjhspi said...

Hi,
This is an interesting question which would be great to get some opinions on.
We find here that some of our regular customers want the newest, freshest batch right out of the pugger and they swear that is the best.
Others want is as old as we have presuming it hasn't gotten too dry.
The bacteria content of the clay which may be completely unique to your situation, drives subtle changes to the body. So your best bet is to do some trial and error.
The subjective nature and large number of variables working with natural clay will make it a little tough to quantify, but you may see that at 4 weeks, all of a sudden it seems a lot more plastic, but then again it may not change much at all.
Let us know how you make out
TJH

1:48 PM  
Anonymous Anonymous said...

Help please! I am a beginning potter learning on my own right now. Can you tell me why my bowls and things are cracking in the drying process after I make them? I have had success in making some things but now my clay is beginning to crack after I hand build the piece and it is drying waiting to be fired.

7:48 AM  
Blogger tjhspi said...

Hi,
To help you I need some specifics:

What clay are you using?
Are you covering it to dry it?
Is it in a room with forced air heat?
Are you wheel throwing or hand building?

Let me know and I'll try to help..
TJH

6:27 AM  
Anonymous Anonymous said...

Thank you for responding. The clay I purchased at Hobby Lobby and do not have the content info or label any longer but it was a general purpose light gray colored clay. It dries almost white. I am drying these in my house with usual electric furnace heating the whole home. I didn't have this problem before we turned on the furnace actually. They aren't located where air is being blowed directly on them though but the air is dryer. I am hand building and smoothing with some water and then etching also. They are almost a quarter of an inch thick. I have had this clay for several months it is still moist but could it be getting old?

11:23 AM  
Blogger tjhspi said...

There are a couple of things which cause cracking.
First of all be sure to wedge the clay well with the ram's head technique or other.The age of the clay should not be a problem.

If the crack is "S" shaped in the bottom, that is usually related to not coning well if you are throwing on the wheel.


If this are all hand-built things then what is happening is that parts are drying faster next to areas which are drying slower so the piece is shrinking at different rates.
Make sure the bottom has a chance to dry as the sides are drying:
Either set it on plaster which will absorb some of the bottom moisture or try putting them up on a rack: an oven rack will do... just so there is air circulation underneath.
Also cover the whole piece with some thin plastic: grocery bag will do, so that the things dry slower.
This should help give the bottom a chance to keep pace with the rapidly drying sides.
You can even mist it a bit, again so the sides don't get too dry before the rest...
Let me know if this works out...
tim

4:42 AM  
Anonymous Anonymous said...

Thank you very much for your help. I am going to try to do what you said to keep my pieces from breaking. It is wonderful to find some help online. I am in an area where there is no close ceramics shop. I am going to bookmark your blog site.

6:01 AM  
Blogger adrian8806 said...

I was curious if it's necessary to glaze a tobacco pipe for use after baking?

I've already done so without glaze and it seems to be solid. I'd like to know to be certain before use.

I know the clay is labeled as non toxic, it's a clay body type T1 from Sheffield.

Thanks.

2:36 PM  
Blogger tjhspi said...

HI.
You could glaze the outside for some added beauty...
I would leave the inside unglazed though.
tjh
sheffield

5:03 AM  

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