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getting rid off hairline cracks.

updated tue 26 feb 08

 

asim mahmood on thu 21 feb 08


From: asim_mahmood55@msn.comTo: clayart@lsv.ceramics.orgSubject: RE: Text o=
n a glazeDate: Thu, 21 Feb 2008 17:43:49 -0500



While joining the handles with teapots I always ensure for their =
slow drying to avoid hairline cracks at the joints. Last weekend despite al=
l the precautions I did get those cracks on some of the teapots and tried t=
o cover them up by rubbing gently the effected area with my thumb at bone d=
ry stage and was happy to note their disappearance. After the bisque firing=
I could see again the appearance of those hairline cracks at the joints bu=
t in lesser intensity. I am sure that the cracks are just on the outer surf=
ace / superficial as the slip used for joining was a bit thin but deep insi=
de the joints are firm.
=20
These teapots are in dark stoneware body and their outer surface=
s in the joints areas are to be kept glaze free but still these have to und=
er go glaze firing at cone 6 oxidation. Now my question is as to how can I =
save and retrieve these 9 teapots by getting rid off those cracks? Can I st=
ill fill them with something other than the glaze? I have to do the next fi=
ring on 02/22/2006. I need your advice but next time I will be extremely ca=
reful.
Thanks in advance, Asim Mahmood.

Connect and share in new ways with Windows Live. Get it now!=20
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Need to know the score, the latest news, or you need your Hotmail=AE-get yo=
ur "fix".
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Victoria E. Hamilton on fri 22 feb 08


Asim -

I have found some success using a thick paperclay slip to repair join cracks
and divots at the leather hard or even bone dry stages.

Use bone dry clay trimmings and shredded toilet paper (2 to 1) slaked in
water to cover by 1 inch. When the clay/paper material is completely
saturated (may take a day or so) pour off as much water as you can easily,
then mix with a small kitchen mixer or run it through a blender. It should
be very thick. You could also use vinegar as part of the water solution.
This mixture can get pretty fragrant and the vinegar helps to combat some of
that.

Good luck and take care.

Vicki Hamilton
Millennia Antica Pottery
Seattle, WA

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of asim mahmood
Sent: Thursday, February 21, 2008 2:46 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Getting rid off hairline cracks.

From: asim_mahmood55@msn.comTo: clayart@lsv.ceramics.orgSubject: RE: Text on
a glazeDate: Thu, 21 Feb 2008 17:43:49 -0500



While joining the handles with teapots I always ensure for their
slow drying to avoid hairline cracks at the joints. Last weekend despite all
the precautions I did get those cracks on some of the teapots and tried to
cover them up by rubbing gently the effected area with my thumb at bone dry
stage and was happy to note their disappearance. After the bisque firing I
could see again the appearance of those hairline cracks at the joints but in
lesser intensity. I am sure that the cracks are just on the outer surface /
superficial as the slip used for joining was a bit thin but deep inside the
joints are firm.

These teapots are in dark stoneware body and their outer surfaces
in the joints areas are to be kept glaze free but still these have to under
go glaze firing at cone 6 oxidation. Now my question is as to how can I save
and retrieve these 9 teapots by getting rid off those cracks? Can I still
fill them with something other than the glaze? I have to do the next firing
on 02/22/2006. I need your advice but next time I will be extremely careful.
Thanks in advance, Asim Mahmood.

Connect and share in new ways with Windows Live. Get it now!
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__
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Bobbie Fenton on fri 22 feb 08


Asim-

I've had some luck with filling the bisque cracks with mud dry as I could work it with damp fingertips and refiring. When it dries, smooth it in just as you did in the bone dry stage. Helps is you can add a little finely powdered grog (grind up a piece of broken bisque with a hammer) so it won't shrink much. It's not a 100% cure, but have done it successfully.

Also, when you have cracks in your dry greenware, rub FINE bone dry powder from cleaning your ware (usually in the bottom of your pan is the best place to find it) into the cracks - push with tips of your nails or anything with a fine edge - BE CAREFUL not to push too hard so you don't crack it more, but pack it tightly. Wet lightly with sponge, but don't soak it. You just want to dampen the top of the clay. Rub dry powder again when it's dry to build up anything that may have sunk from drying. If it's a larger crack, you can use mud as dry as you can still work with damp fingertips, mix with small pebbles of dry mud - then wet once you pack it in. Spritz lightly and cover with a plastic bag and let dry very slowly. This is very tricky and you have to have a LOT of patience and a light touch and my success has been far more limited, but I have done it. If you low fire your 'problem children' first - you can build it (your repair) up and sand it down after the firing.
It's a lot of trouble - but if you have something you have a lot of time in - it is worth the effort.

Another technique - though this takes forever - is rewetting your ware and pressing in clay that is of the same, or a hair dryer consistency. Put it in a plastic bag, spray the ware lightly with water and the inside of the bag - keeping doing this daily until the ware is wet again - but don't spray so much that the bottom of the bag accumulates water or the bottom will melt out and you'll have a bigger problem. This is another of those really tricky cures - but it can work. Take your ware out when it is dehydrated - using a tool with a round or blunt point, push around the cracks so that they give once again and 'forget' about being a crack - push mud of the same consistency into the crack and smoosh it into the crack so that it joins, preferably built up just a little more and over the existing ware. Put it back in the bag and tie lightly, allow to dry in the bag very slowly.

Some folks swear using vinegar instead of water for repairs works better, but I've never tried it. There were a lot of posts here recently on the subject - so you might check those out as it could increase your success.

Hope this helps.
Bobbie
www.mississippistonepottery.com

asim mahmood wrote: From: asim_mahmood55@msn.comTo: clayart@lsv.ceramics.orgSubject: RE: Text on a glazeDate: Thu, 21 Feb 2008 17:43:49 -0500



While joining the handles with teapots I always ensure for their slow drying to avoid hairline cracks at the joints. Last weekend despite all the precautions I did get those cracks on some of the teapots and tried to cover them up by rubbing gently the effected area with my thumb at bone dry stage and was happy to note their disappearance. After the bisque firing I could see again the appearance of those hairline cracks at the joints but in lesser intensity. I am sure that the cracks are just on the outer surface / superficial as the slip used for joining was a bit thin but deep inside the joints are firm.

These teapots are in dark stoneware body and their outer surfaces in the joints areas are to be kept glaze free but still these have to under go glaze firing at cone 6 oxidation. Now my question is as to how can I save and retrieve these 9 teapots by getting rid off those cracks? Can I still fill them with something other than the glaze? I have to do the next firing on 02/22/2006. I need your advice but next time I will be extremely careful.
Thanks in advance, Asim Mahmood.

Connect and share in new ways with Windows Live. Get it now!
_________________________________________________________________
Need to know the score, the latest news, or you need your HotmailŪ-get your "fix".
http://www.msnmobilefix.com/Default.aspx
______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org

You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/

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Dale Cochoy on fri 22 feb 08


Victoria,
Your mixture is very similar to something I used to use, although I didn't
mix with water and let sit. I just mix dry clay ( or slip in a pinch) with
shreaded TP and ad some pancake syrup. The syrup seems to slow down the
drying real well. once in a while I'll coat with wax but not usually. I
often have just painted pancake syrup over the repair to slow it all down
while drying.. This works pretty good for my once-in-a-while needed repair.

BTW, re: using vinegar. I was reading the posts last few days on adding
vinegar. I used to do this in my slip for slab building, years ago. I was
looking for a solution to seam cracks and attached feet falling off. I
stopped using it after I started noticing some dark seams showing where
mold developed on slip while drying/waiting to get fired. The firing left it
darker just at seams?. On unglazed pots this looked BAD. Also, the tubs of
slip I have around all started molding in the tubs. I stopped using vinegar
in anything, slip or otherwise and found NO differences in my seam
reliability. Years ago I discovered it wasn't the vinegar but just using
better techniques to score pieces, better slip made from dried/powdered clay
( less water) and better drying techniques. I RARELY have a seam problem
now.
Regards,
Dale Cochoy
Wild Things Bonsai Studio
Hartville, Ohio Zone 5
www.WildThingsBonsai.com
DCochoy@neo.rr.com


----- Original Message -----
From: "Victoria E. Hamilton" Subject: Re: Getting rid off hairline cracks.


> I have found some success using a thick paperclay slip to repair join
> cracks
> and divots at the leather hard or even bone dry stages.
>
> Use bone dry clay trimmings and shredded toilet paper (2 to 1) slaked in
> water to cover by 1 inch. When the clay/paper material is completely
> saturated (may take a day or so) pour off as much water as you can easily,
> then mix with a small kitchen mixer or run it through a blender. It
> should
> be very thick. You could also use vinegar as part of the water solution.
> This mixture can get pretty fragrant and the vinegar helps to combat some
> of
> that.
>
> Good luck and take care.
>
> Vicki Hamilton
> Millennia Antica Pottery
> Seattle, WA

Ron Roy on mon 25 feb 08


Hi Asim,

I just use vinegar to join handles - you don't need to rough the clay up -
just wet both surfaces and push the clay together, Vinegar is good for
softening handles that get too dry as well - so they will bend without
cracking.

If you must use slip make sure it's deflocculated - the crakes are coming
from the slip shrinking too much as it dries.

RR

>From: asim_mahmood55@msn.comTo: clayart@lsv.ceramics.orgSubject: RE: Text
>on a glazeDate: Thu, 21 Feb 2008 17:43:49 -0500
>
>
>
> While joining the handles with teapots I always ensure for their
>slow drying to avoid hairline cracks at the joints. Last weekend despite
>all the precautions I did get those cracks on some of the teapots and
>tried to cover them up by rubbing gently the effected area with my thumb
>at bone dry stage and was happy to note their disappearance. After the
>bisque firing I could see again the appearance of those hairline cracks at
>the joints but in lesser intensity. I am sure that the cracks are just on
>the outer surface / superficial as the slip used for joining was a bit
>thin but deep inside the joints are firm.
>
> These teapots are in dark stoneware body and their outer
>surfaces in the joints areas are to be kept glaze free but still these
>have to under go glaze firing at cone 6 oxidation. Now my question is as
>to how can I save and retrieve these 9 teapots by getting rid off those
>cracks? Can I still fill them with something other than the glaze? I have
>to do the next firing on 02/22/2006. I need your advice but next time I
>will be extremely careful.
> Thanks in advance, Asim Mahmood.

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

Lee on mon 25 feb 08


I would think twice about rewetting a hairline crack on a handle joint
in greenware. If it is an open clay, it may make the crack worse.
Bisque is more forgiving though.

I find that simple burnishing does the trick.



--
Lee in Mashiko, Tochigi Japan
http://mashikopots.blogspot.com/

"Let the beauty we love be what we do." - Rumi