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sand mesh for cracking claybody

updated tue 20 nov 07

 

mshelomith on sun 11 nov 07


Hey, Tracy...

I had to laugh, having dealt with techs that leave me, after a desperate
call, feeling that I had just
had a conversation with a box of rocks.

Maybe, I hope, you'll get lucky...



Miriam
On the way out the door for the last dog walk of this day with the gang of
10. They take me along
because I hold the leashes.

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Tracy Bradford
Sent: Sunday, November 11, 2007 7:29 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: sand mesh for cracking claybody

Dan and Miriam,
No, I haven't called the techs. I know I should but to tell you the
truth I've called them in the past and they've never really impressed
me as being helpful. But, you never know, maybe others have indeed
had the same problem and they've found a solution. Perhaps tomorrow
I'll give them a ring....
T

Tracy Bradford on sun 11 nov 07


I've been having major problems with my claybody cracking since about
August of this summer. I've been trying every conceivable idea to
manage and fix the problem all to no avail. I've slow dried, med.
dried, fast dried. I've trimmed, compressed, humidified,
de-humidified. I've begged, pleaded and cried and still those gosh
durn s-cracks greet me when I enter the studio.

I should mention I've been using this same clay body for quite awhile
with absolutely no s-crack problems. Its just been these clay pallets
I've ordered this summer that are giving me the hard time (all with
the same batch number). The clay is Miller 510. Stoneware.

So, I've decided I'm just going to follow someone's recommendation of
adding sand to the 75 lb. batches I put in my pugmill. Could someone
please giving me a starting point for what size mesh sand I should get
and ..... what would be a good percentage to start with for a 75 lb
batch? These are wheel thrown pots I make.

Tracy

Dan Semler on sun 11 nov 07


Hi Tracy,

If you've used this body for a while without problems, with the
same processes, and this batch is giving problems, I would ask the
manufacturer of the body about it. Have they changed anything,
substituted a material or something like that ? If you have asked
them, what did they say ?

Thx
D

Marek & Pauline Drzazga-Donaldson on sun 11 nov 07


Dear Tracy,

I use kiln dried sand - sand usually used for filling the gaps between =
patio tiles. I do not sieve it and add it to my clay damp (for better =
mixing) and depending on what thickness (from bricks to slabs for tiles) =
, from 15% - up to 40% +. For all my thrown work I use a minimum of 15% =
going up to 30% for the thicker pieces.

happy potting Marek



Hand made Architectural Ceramics from No9 Studio UK www.no9uk.com
Fully Residential Pottery Courses and more at Mole Cottage =
www.moleys.com
"Tips and Time Travel from a Vernacular Potter" reviews on =
www.keramix.com
an irreverent point of view after 35 years in the game Marek =
Drzazga-Donaldson =20
Assemble a dragon finial at www.dragonfinials.co.uk
Free Works and Mole Cottage DVD's and Video content on all the sites
Drzazga Video Promotions at www.drzazga.co.uk Submit address for DVD

Tracy Bradford on sun 11 nov 07


Dan and Miriam,
No, I haven't called the techs. I know I should but to tell you the
truth I've called them in the past and they've never really impressed
me as being helpful. But, you never know, maybe others have indeed
had the same problem and they've found a solution. Perhaps tomorrow
I'll give them a ring....
T

Tracy Bradford on sun 11 nov 07


Thank you Marek, very helpful!
T

On 11/11/07, Marek & Pauline Drzazga-Donaldson wrote:
> Dear Tracy,
>
> I use kiln dried sand - sand usually used for filling the gaps between patio tiles. I do not sieve it and add it to my clay damp (for better mixing) and depending on what thickness (from bricks to slabs for tiles) , from 15% - up to 40% +. For all my thrown work I use a minimum of 15% going up to 30% for the thicker pieces.
>
> happy potting Marek
>
>
>
> Hand made Architectural Ceramics from No9 Studio UK www.no9uk.com
> Fully Residential Pottery Courses and more at Mole Cottage www.moleys.com
> "Tips and Time Travel from a Vernacular Potter" reviews on www.keramix.com
> an irreverent point of view after 35 years in the game Marek Drzazga-Donaldson
> Assemble a dragon finial at www.dragonfinials.co.uk
> Free Works and Mole Cottage DVD's and Video content on all the sites
> Drzazga Video Promotions at www.drzazga.co.uk Submit address for DVD
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
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>
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>

Paul Borian on mon 12 nov 07


you should really make some test bars and measure the shrinkage and
compare it to what the stated shrinkage rate is, according to the
manufacturer. At one point i had some cracking problems with the clay body
i mix when i was not using enough non-plastics - certain items would crack
while others would not so it was a little tricky to troubleshoot. But as
soon as i started increasing the non-plastics (in my case, mullite and
kyanite) they went away for good so i know the cracks were caused by
excessive shrinkage and my guess is that is your problem as well (assuming
that you are taking care to even out the drying process).
I would not buy any more of that clay until you figure out what is going
on because it sounds to me like you are not getting the same product you
once were.

Paul

Ron Roy on mon 19 nov 07


This is mesage from last week that never got distributed - RR

Hi Tracy,

It might be there was a mistake made when mixing that clay - certainly call
the manufacturer and ask if they have tested it or had other complaints.

Some clay companies will do the right thing and at least replace the clay.

If you want to test to see what the plasticity is I can send the
instructions. Clay can crack because there is too much platicity or too
little.

RR

>I've been having major problems with my claybody cracking since about
>August of this summer. I've been trying every conceivable idea to
>manage and fix the problem all to no avail. I've slow dried, med.
>dried, fast dried. I've trimmed, compressed, humidified,
>de-humidified. I've begged, pleaded and cried and still those gosh
>durn s-cracks greet me when I enter the studio.
>
>I should mention I've been using this same clay body for quite awhile
>with absolutely no s-crack problems. Its just been these clay pallets
>I've ordered this summer that are giving me the hard time (all with
>the same batch number). The clay is Miller 510. Stoneware.
>
>So, I've decided I'm just going to follow someone's recommendation of
>adding sand to the 75 lb. batches I put in my pugmill. Could someone
>please giving me a starting point for what size mesh sand I should get
>and ..... what would be a good percentage to start with for a 75 lb
>batch? These are wheel thrown pots I make.
>
>Tracy

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0