David Woof on mon 6 sep 10
Hi Curtis=3D2C
As always my first "helpful opinion"=3D2C as you say=3D2C is to suggest tha=
t yo=3D
u educate yourself about the materials you are using. Now I know we all ta=
=3D
ke short cuts in our busy lives and asking on Clayart is good because it he=
=3D
lps others as well so....=3D20
=3D20
Kyanite is a form of silica and has a crystalline structure like "pointy ne=
=3D
edles" (layperson's term to be sure) which help lace and interlock the clay=
=3D
body materials together adding strength in the plastic wet and green dryin=
=3D
g phases of the pot or sculpture's construction and handling. Anything coa=
=3D
rser than 90/100 mesh will feel like throwing with clay laced with tiny nee=
=3D
dles=3D2C and more than 12% in this 100 mesh range in a clay body starts to=
c=3D
ause two problems=3D3B loss of plasticity vs. adding more plastic materials=
a=3D
nd getting the feeling you are throwing with snot=3D2C and/or having drying=
w=3D
arpage/excessive shrinkage problems.
=3D20
Based on what I've told you do you think you should leave the kyanite in th=
=3D
e slip? In this application it functions as a mineral fiber not unlike th=
=3D
e wood fibers from the paper pulp. Easy test: try a small batch of each=
=3D
=3D3B with and w/out the kyanite. Myself I would leave it in and get on w=
it=3D
h it. Let us know what you did and how it worked for you.
=3D20
David Woof....Clarkdale=3D2C Arizona......P.S. less opinions and more facts=
w=3D
ould be on par with replacing guns with dictionaries.
________________________________________________________________________
1a. Paper Clay Slip
Posted by: "Curtis Nelson" curtn@EARTHLINK.NET=3D20
Date: Mon Sep 6=3D2C 2010 4:23 pm ((PDT))
I use paper clay slip that I make from commercial raku clay mixed with hous=
=3D
e
insulation for the cellulose. I use it successfully in hand building for
joining slabs anywhere from approaching leather hard up to pretty stiff sla=
=3D
bs.
Now I have a nearly finished sculpture with a lot of hours in it already. I=
=3D
t
cries out for mending three cleanly broken-off parts. I knocked them off
when everything was bone dry.
Reading about P'clay leads me to believe that P'slip does a super job of
rejoining bone dry parts.
The question is should the kyanite in my raku clay (12%) be sieved out for
mending bone dry to bone dry. I believe grogged slip is less successful tha=
=3D
n
with the grog removed. True?
So I used a 120 mesh sieve to get the kyanite out of a 1/2 cup or so of
P'slip. The result feels and looks so smooth that I wonder if I've
inadvertently removed the paper fibers=3D2C leaving the slip too clean (no
kyanite=3D2C no paper fiber) to do its job as a mender.
Any helpful opinions out there?
=3D20
=3D20
=3D
Snail Scott on mon 6 sep 10
On Sep 6, 2010, at 3:11 PM, Curtis Nelson wrote:
> The question is should the kyanite in my raku clay (12%) be sieved
> out for
> mending bone dry to bone dry. I believe grogged slip is less
> successful than
> with the grog removed...
The ideal slip joint (repair joint or original
construction) is strongest when the minimum
necessary amount of slip is present after
attachment and not more. Slip has more water than
clay, and thus shrinks more, so why put a big 'ol layer
of shrinky stuff in the middle of a critical connection?
You should use just enough to fill any gaps, and just
enough extra to squish out a bit and ensure that
there was indeed enough. So...
Having coarse grog in your 'original construction'
slip is no big deal, since the softer clay will
accommodate it OK, but when repairing bone-dry
or bisque clay, coarse grog will just keep the joint
open by the diameter of the grog instead of letting
it be as tight together as possible. When a joint is
caused by breakage, the parts usually fit perfectly,
so you want to mess that up as little as you can.
Using paper in the joining slip helps reduce the
shrinkage due to water, so that's one reason for
its value (the other is tensile strength), but why
ask it to work harder by making a joint that's all
full of chunks and thus thicker than needed?
I agree with your suspicion that screening the slip
after mixing may remove a fair amount of paper, but
I'll bet a lot of it comes through, if it is truly well mixed.
In an ideal paper slip there will be no chunks, but
rather, individual tiny strands of paper fiber each
surrounded by a coating of slip. Screening _may_
remove some paper but better blend the remainder.
I'm not sure, though, so your own experience must
be the test. If the results of the screening don't serve,
however, do it otherwise. I make paper slip by drying
my clay, crushing it it, screen out the grog (if it's
large), and then add it to the damp paper pulp. (I
use vinegar for the liquid.)
-Snail
Curtis Nelson on mon 6 sep 10
I use paper clay slip that I make from commercial raku clay mixed with ho=
=3D
use
insulation for the cellulose. I use it successfully in hand building for
joining slabs anywhere from approaching leather hard up to pretty stiff s=
=3D
labs.
Now I have a nearly finished sculpture with a lot of hours in it already.=
=3D
It
cries out for mending three cleanly broken-off parts. I knocked them off
when everything was bone dry.
Reading about P'clay leads me to believe that P'slip does a super job of
rejoining bone dry parts.
The question is should the kyanite in my raku clay (12%) be sieved out fo=
=3D
r
mending bone dry to bone dry. I believe grogged slip is less successful t=
=3D
han
with the grog removed. True?
So I used a 120 mesh sieve to get the kyanite out of a 1/2 cup or so of
P'slip. The result feels and looks so smooth that I wonder if I've
inadvertently removed the paper fibers, leaving the slip too clean (no
kyanite, no paper fiber) to do its job as a mender.
Any helpful opinions out there?
Vince Pitelka on mon 6 sep 10
Curtis Nelson wrote:
"Reading about P'clay leads me to believe that P'slip does a super job of
rejoining bone dry parts. The question is should the kyanite in my raku cla=
y
(12%) be sieved out for mending bone dry to bone dry. I believe grogged sli=
p
is less successful than with the grog removed. True?"
Hi Curtis -
I don't think you want to screen out the kyanite. We use a lot of what we
call our "raku body." We don't do much raku anymore, but we use it for
sculpture and for bonfiring. It contains equal parts Goldart, fire clay,
ball clay, and 50M grog. If something important breaks or cracks, I bring
out the paper-clay slurry made from this claybody. It works amazingly well
for joining bone-dry pieces. I make it from equal parts toilet paper pulp
with the water squeezed out of it, and dry crushed claybody, and I add
enough pure vinegar (white or cider) to make a slurry. This stuff works
great. We do not screen out the grog, and this claybody contains 25% grog.
We wet both surfaces with pure vinegar and lightly roughen them with a stif=
f
toothbrush or small wire brush, add the slurry, and join. I also make the
same recipe from other claybodies with equal success. This is something yo=
u
would never want to use on a functional pot, but for sculpture it is great.
If it is a functional pot, recycle the clay and make another one.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Alisa Liskin Clausen on wed 8 sep 10
Hi Kurt
In my studio I have different slips for different applications. Mostly
colored slips, but for mending, I use a mix of Peggy Heer's Pooze and my ow=
n
addition of paper, thus Papooze. I dry out the same clay body as what I am
fixing, crush it finely, add paper pulp, water, vinegar and honey. No fixe=
d
quantities. But if I gave you an order which refers to quantities from
most to least, it would be
clay, paper pulp, water, honey and vinegar. Mix it up, use it thickly. I
do not mix big quantities because it does not keep well due to the food in
it. It works very well to repair cracks and hold broken parts on.
Best regards from Alisa in Denmark
--
Alisa Liskin Clausen
Troldskovvej 42
DK 6200 Aabenraa
Denmark
(45) 20 24 66 40
ivor and olive lewis on wed 8 sep 10
I agree with Snail Scott Devising an adhesive slip is not a difficult thin=
g
to do. But joining bone dry clay parts with an ordinary clay slurry present=
s
some hurdles.
I believe when Paper Clay was introduced to the modern ceramic audience it
was found that a joining slip that had fibres in it proved to be a most
successful way of assembling. parts.
I recall a meeting of the Potters Guild of SA several years ago when Brian
Gartside gave a lecture on the topic of Paper Clay. He told us about packin=
g
parts for a demonstration on another continent,( it may have been at
Aberystwyth). I cannot recall the precise details but the slabs Brian had
prepared for his demo had dried out in transit. He use a paper clay slip to
assemble his construction and demonstrated its strength..
I can see no reason why you should remove Kyanite unless it is coarse enoug=
h
to feel when the clay is smeared between your fingers. I could suggest that
you keep your water content to a minimum. This can be done by adding a
deflocculant such as Darvan or Dispex and allowing the mixture to thicken b=
y
evaporation.. The science behind the technology of this process of making a
good adhesive clay slip is complex, but having the minimum volume of water
in a free flowing slip helps to overcome shrinkage problems that might lead
to serious cracks during drying or firing.
Regards,
Ivor Lewis,
REDHILL,
South Australia
Eleanora Eden on wed 8 sep 10
Hi Alisa,
The recipe I have for Peggy's spooze uses corn syrup, not honey.
It doesn't have a limited shelf life. I also make a paper-clay variety,
in the same manner. I use shredded toilet tissue, letting it soak
for awhile in the vinegar to break it down before proceeding.
Also, I find it works best if I wet the work before applying the goop.
Eleanora
>Hi Kurt
>In my studio I have different slips for different applications. Mostly
>colored slips, but for mending, I use a mix of Peggy Heer's Pooze and my o=
wn
>addition of paper, thus Papooze. I dry out the same clay body as what I a=
m
>fixing, crush it finely, add paper pulp, water, vinegar and honey. No fix=
ed
>quantities. But if I gave you an order which refers to quantities from
>most to least, it would be
>clay, paper pulp, water, honey and vinegar. Mix it up, use it thickly. I
>do not mix big quantities because it does not keep well due to the food in
>it. It works very well to repair cracks and hold broken parts on.
>
>Best regards from Alisa in Denmark
>
--
Bellows Falls Vermont
www.eleanoraeden.com
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