Paul Borian on tue 19 jan 10
i stopped by the studio i used to work at yesterday and was watching a
potter put large handles on some really interesting pitchers, and i was
surprised that he did not use any scoring lines - he just put some slip on
there and attached the handles. I would have thought for these kinds of pot=
s
it would be worth it to score them just so the handles don't come off so i
asked him why he did not do so.
Now, a little bit about this guy - they basically just flagged him down one
day when he was walking down the sidewalk in front of the studio during a
busy time when some extra help was needed. He spoke almost no english at al=
l
but there was someone else working there who just happened to know spanish
so they started talking and gave him a temporary job doing unskilled work
around the studio. So, he came with no experience and no pre-conceived
notions about pottery and this evidently works to his favor because now he
is an excellent potter.
So, as far as the handles go, i think he basically just did not understand
why you would have to use score lines so he didn't use them. He did for a
while because the owner told him to when he was learning but then one day h=
e
stopped and never went back, and his handles never come off.
Now i think i should learn from this guy because it would save me a lot of
time so i will start testing this method out.
Just wondering if anyone else works this way? Maybe scoring was just a
habit i learned because all the other potters i was around were doing it so
it just seemed like the "correct" technique to use?
N. Gallagher on tue 19 jan 10
My instructor doesn't score or use slip. Plain water only. He does
all sorts of handles this way.
I've only been brave enough to try and attach mug handles like this
so far, but as long as your clay isn't too dry, it works great! Let
the water dry just until the sheen disappears and voila - the handle
attaches firmly with no cracking.
Nancy
Bob Johnson on tue 19 jan 10
In a recent workshop with Steven Hill, he told us that scoring was
unnecessary when attaching two pieces of clay in which the clay platelets o=
n
both pieces have been made parallel by pulling or throwing. Both processes
align the clay particles parallel to the surface, and so they can form a
strong bond without scoring. However, when a handle is butted to the vessel=
,
the clay particles are aligned in different (perpendicular) directions, so
they need a scored junction, if the handle is to be strong. Extruded or sla=
b
sections also need scoring.
Bob
Roseburg, Oregon
steve graber on tue 19 jan 10
i don't do larger handle things, but for mugs=3DA0if/when the mug is semi-w=
et=3D
, early leather,=3DA0i skip scoring.=3DA0 when leather or harder leather i =
have=3D
to score it.=3DA0 maybe he adds handles when the pots are still pretty wet=
?=3D
=3DA0 is this a high humidity climate?=3DA0 =3D0A=3DA0Steve Graber, Graber'=
s Potter=3D
y, Inc=3D0AClaremont, California USA=3D0AThe Steve Tool - for awesome textu=
re o=3D
n pots! =3D0Awww.graberspottery.com steve@graberspottery.com =3D0A=3D0A=3D0=
AOn Lagu=3D
na Clay's website=3D0Ahttp://www.lagunaclay.com/blogs/ =3D0A=3D0A=3D0A=3D0A=
----- Orig=3D
inal Message ----=3D0A> From: Paul Borian =3D0A> To=
: Cl=3D
ayart@LSV.CERAMICS.ORG=3D0A> Sent: Tue, January 19, 2010 11:18:47 AM=3D0A> =
Subj=3D
ect: anyone attaching handles without scoring lines?=3D0A> =3D0A> i stopped=
by =3D
the studio i used to work at yesterday and was watching a=3D0A> potter put =
la=3D
rge handles on some really interesting pitchers, and i was=3D0A> surprised =
th=3D
at he did not use any scoring lines - he just put some slip on=3D0A> there =
an=3D
d attached the handles. I would have thought for these kinds of pots=3D0A> =
it=3D
would be worth it to score them just so the handles don't come off so i=3D=
0A=3D
> asked him why he did not do so.=3D0A> Now, a little bit about this guy - =
th=3D
ey basically just flagged him down one=3D0A> day when he was walking down t=
he=3D
sidewalk in front of the studio during a=3D0A> busy time when some extra h=
el=3D
p was needed. He spoke almost no english at all=3D0A> but there was someone=
e=3D
lse working there who just happened to know spanish=3D0A> so they started t=
al=3D
king and gave him a temporary job doing unskilled work=3D0A> around the stu=
di=3D
o. So, he came with no experience and no pre-conceived=3D0A> notions about =
po=3D
ttery and this evidently works to his favor because now he=3D0A> is an exce=
ll=3D
ent potter.=3D0A> So, as far as the handles go, i think he basically just d=
id=3D
not understand=3D0A> why you would have to use score lines so he didn't us=
e =3D
them. He did for a=3D0A> while because the owner told him to when he was le=
ar=3D
ning but then one day he=3D0A> stopped and never went back, and his handles=
n=3D
ever come off.=3D0A> Now i think i should learn from this guy because it wo=
ul=3D
d save me a lot of=3D0A> time so i will start testing this method out.=3D0A=
> Ju=3D
st wondering if anyone else works this way? Maybe scoring was just a=3D0A> =
ha=3D
bit i learned because all the other potters i was around were doing it so=
=3D
=3D0A> it just seemed like the "correct" technique to use?=3D0A=3D0A=3D0A=
=3D0A
Craig Edwards on tue 19 jan 10
Hi Paul: I don't score handles and it works just fine.
--
Make Good Pots
~Craig
New London MN
http://woodfiredpottery.blogspot.com/
Kiln building workshop October 15-22
Taku, Japan
karatsupots-workshop.blogspot.com/
On Tue, Jan 19, 2010 at 1:18 PM, Paul Borian wrote=
:
> i stopped by the studio i used to work at yesterday and was watching a
> potter put large handles on some really interesting pitchers, and i was
> surprised that he did not use any scoring lines - he just put some slip o=
n
> there and attached the handles. I would have thought for these kinds of
> pots
> it would be worth it to score them just so the handles don't come off so =
i
> asked him why he did not do so.
> Now, a little bit about this guy - they basically just flagged him down o=
ne
> day when he was walking down the sidewalk in front of the studio during a
> busy time when some extra help was needed. He spoke almost no english at
> all
> but there was someone else working there who just happened to know spanis=
h
> so they started talking and gave him a temporary job doing unskilled work
> around the studio. So, he came with no experience and no pre-conceived
> notions about pottery and this evidently works to his favor because now h=
e
> is an excellent potter.
> So, as far as the handles go, i think he basically just did not understan=
d
> why you would have to use score lines so he didn't use them. He did for a
> while because the owner told him to when he was learning but then one day
> he
> stopped and never went back, and his handles never come off.
> Now i think i should learn from this guy because it would save me a lot o=
f
> time so i will start testing this method out.
> Just wondering if anyone else works this way? Maybe scoring was just a
> habit i learned because all the other potters i was around were doing it =
so
> it just seemed like the "correct" technique to use?
>
--
Make Good Pots
~Craig
New London MN
http://woodfiredpottery.blogspot.com/
Kiln building workshop October 15-22
Taku, Japan
karatsupots-workshop.blogspot.com/
Steve Mills on tue 19 jan 10
When I was at college my natural inclination was (and still is) to *not* do
what I was told I *must* do.
That's the way we all learn how to live, make, and love; Pavlovian Response=
!
As George Bernard Shaw said: "The Golden Rule is, there are NO Golden Rules=
"
Steve M
2010/1/19 Paul Borian
> i stopped by the studio i used to work at yesterday and was watching a
> potter put large handles on some really interesting pitchers, and i was
> surprised that he did not use any scoring lines - he just put some slip o=
n
> there and attached the handles. I would have thought for these kinds of
> pots
> it would be worth it to score them just so the handles don't come off so =
i
> asked him why he did not do so.
>
--
Steve
Bath
UK
www.mudslinger.me.uk
Marcia Selsor on tue 19 jan 10
I think Robin Hopper doesn't score handles.=3D20
Whatever works for you...
Marcia Selsor
On Jan 19, 2010, at 1:18 PM, Paul Borian wrote:
> i stopped by the studio i used to work at yesterday and was watching a
> potter put large handles on some really interesting pitchers, and i =3D
was
> surprised that he did not use any scoring lines - he just put some =3D
slip on
> there and attached the handles. I would have thought for these kinds =3D
of pots
> it would be worth it to score them just so the handles don't come off =3D
so i
> asked him why he did not do so.
> Now, a little bit about this guy - they basically just flagged him =3D
down one
> day when he was walking down the sidewalk in front of the studio =3D
during a
> busy time when some extra help was needed. He spoke almost no english =3D
at all
> but there was someone else working there who just happened to know =3D
spanish
> so they started talking and gave him a temporary job doing unskilled =3D
work
> around the studio. So, he came with no experience and no pre-conceived
> notions about pottery and this evidently works to his favor because =3D
now he
> is an excellent potter.
> So, as far as the handles go, i think he basically just did not =3D
understand
> why you would have to use score lines so he didn't use them. He did =3D
for a
> while because the owner told him to when he was learning but then one =3D
day he
> stopped and never went back, and his handles never come off.
> Now i think i should learn from this guy because it would save me a =3D
lot of
> time so i will start testing this method out.
> Just wondering if anyone else works this way? Maybe scoring was just a
> habit i learned because all the other potters i was around were doing =3D
it so
> it just seemed like the "correct" technique to use?
>=3D20
Marcia Selsor
http://www.marciaselsor.com
ivor & olive lewis on wed 20 jan 10
Dear Paul Borian,
Handles on mugs and pitchers, collets for spigots and taps, spouts and lugs
on teapots, I would never consider scoring the clay. No need. Wastes time.
Is there a good technical argument for scoring?
Best regards,
Ivor Lewis,
Redhill,
South Australia
Mike on wed 20 jan 10
Hi Paul,
There are probably quite a few factors involved, but I usually find
scoring unnecessary. Just slip, stick, and wiggle ('til I can feel the 2
parts 'stick' nicely).
Sometimes, if I've let the cups get too dry, and the clay is quite fine,
I'll rough up the surface a bit, just in case.
Your mileage may vary,
Mike
Mike
in Taku, Japan
http://karatsupots.com
http://karatsupots.blogspot.com
Kiln Building Workshop, Oct. 15 - 22
http://karatsupots.com/workshop2010/workshop2010.html
http://karatsupots-workshop.blogspot.com/
>
> ----- Original Message ----
>
>> From: Paul Borian
>> To: Clayart@LSV.CERAMICS.ORG
>> Sent: Tue, January 19, 2010 11:18:47 AM
>> Subject: anyone attaching handles without scoring lines?
>>
>> i stopped by the studio i used to work at yesterday and was watching a
>> potter put large handles on some really interesting pitchers, and i was
>> surprised that he did not use any scoring lines - he just put some slip =
on
>> there and attached the handles. I would have thought for these kinds of =
pots
>> it would be worth it to score them just so the handles don't come off so=
i
>> asked him why he did not do so.
>> Now, a little bit about this guy - they basically just flagged him down =
one
>> day when he was walking down the sidewalk in front of the studio during =
a
>> busy time when some extra help was needed. He spoke almost no english at=
all
>> but there was someone else working there who just happened to know spani=
sh
>> so they started talking and gave him a temporary job doing unskilled wor=
k
>> around the studio. So, he came with no experience and no pre-conceived
>> notions about pottery and this evidently works to his favor because now =
he
>> is an excellent potter.
>> So, as far as the handles go, i think he basically just did not understa=
nd
>> why you would have to use score lines so he didn't use them. He did for =
a
>> while because the owner told him to when he was learning but then one da=
y he
>> stopped and never went back, and his handles never come off.
>> Now i think i should learn from this guy because it would save me a lot =
of
>> time so i will start testing this method out.
>> Just wondering if anyone else works this way? Maybe scoring was just a
>> habit i learned because all the other potters i was around were doing it=
so
>> it just seemed like the "correct" technique to use?
>>
>
>
>
>
>
>
Maurice Weitman on wed 20 jan 10
Tom Coleman told me that he hasn't scored in years.
Neither have I.
Sad.
Regards,
Maurice
Snail Scott on wed 20 jan 10
On Jan 19, 2010, at 1:18 PM, Paul Borian wrote:
> ...Maybe scoring was just a
> habit i learned because all the other potters i was around were
> doing it so
> it just seemed like the "correct" technique to use?
I do see many people who seem to score as though
it were a religious ritual, deriving its efficacy from
adherence to tradition or fossilized wishful thinking
instead of empirical evidence or personal experience.
They don't know why they do it; only that they've been
told it's the only way to work. Ironically, most of them
don't score in a very useful way because they never
stopped to think about how or why it works. It's magic;
best not to inquire too closely!
In my experience, the big factor is the nature of the
clay. I can't point to a single factor, but one correlation
I have observed is that clay bodies with a high clay
content tend to be more forgiving of joining techniques.
I seldom if ever score between pieces of similar
dampness when using my regular stoneware, which
is insanely groggy and short. I also seldom score when
using the college's body which is quite plastic and fine.
The clay at the art center, a fairly plastic but slightly
grittier earthenware, requires meticulous joining with
scoring-and-slipping or else separation is inevitable.
Stonewares in general seem to join with less trouble
than earthenwares, but this doesn't apply to every
example. It's also just my perception based on my
own experience with perhaps two dozen clay bodies.
Some folks have mentioned a 'wiggle' as part of their
joining technique, with or without scoring. This, in my
mind, is the most important part, squishing out excess
slip and air (if any), and forcing the clay particles to
mingle.
Although the effects of scoring are, I suspect, at least
partly (or almost entirely entirely) microscopic in scale, I
use a mental model of Velcro when thinking about joining.
Platelets laid side-by-side, as with just pushing one
piece of clay against another, are mainly held together
by the surface tension of the water between them.
When the water evaporates...no more stickiness. (Or
not enough to hold for long). Platelets of clay that are
raked up can interlock with those of another clay piece
pushed into them. This is the purpose of scoring - to
make those 'velcro' teeth happen. Scoring doesn't
have to be deep; it's better if it isn't, since deep cuts
just become weakening air pockets if the slip doesn't
fill them. Besides (and more importantly), it only needs
to be a surface effect. The particles within that piece of
clay are already stuck together; nothing is gained by
ripping them apart with deep mark-making. The best
scoring is very shallow, but covers the whole surface
of the contact area. What's the point of a few cuts across
it? That's just a few percent of the surface area, and the
benefit is minimal. Needle tools are the worst possible
way to score - hard not to go deep, the mark is sharp-
bottomed (and thus doesn't fill well), and it takes a
while to cover a large area. A fork is my beginners'
tool of choice, a serrated rib is better, and a toothbrush
is golden for this: shallow, with maximum raising up
of the surface particles.
Slip is not an adhesive, but a filler, and serves only to
prevent air pockets which might make for a weaker
joint. The less slip, the better. We all know that
unequal rates of shrinkage cause stresses between
damper and drier parts of a piece; adding very damp
clay (slip) right in the middle of a joint is no way to
make it stronger unless it's just enough to fill tiny gaps.
More slip than that is working at cross-purposes.
Bad scoring-and-slipping is worse than none.
The 'shimmy' is all-important because it forces out
excess air and slip, but it also (when no slip is used)
works the particles of soft clay into one another. If
the clay is soft enough, that's sufficient, since only the
outermost surface layer of clay particles is concerned
in the joint. Get them bonded, and nothing else is
necessary. Slippery clays (in my experience, this
includes most talc bodies) and stiff clays seem to have
trouble with this because the clays don't really get
a grip on each other to create that particle interlock.
For these, scoring and slipping may be essential.
But it's far from necessary for every clay joint. It all
comes down to your working methods (soft or stiff)
and, most importantly, your clay body.
Not sure of the reasons for the correlation between
clay content in a clay body and ease of joining, but
I suspect it's an entirely different phenomenon than
just the physical interlock of particles. (Ionic, maybe?)
Just a guess, though.
All of this is purely my own opinion based on personal
experience; I offer it into the general information pool
of Clayart. The experiences of others will inevitably
vary, adding further to our shared knowledge base.
-Snail
Ron Roy on wed 20 jan 10
My understanding is - if the clay gets too hard - scoring helps to re
wet it. The scoring should be wiped out before joining - no point in
having air in the joint.
RR
Quoting ivor & olive lewis :
> Dear Paul Borian,
>
> Handles on mugs and pitchers, collets for spigots and taps, spouts and lu=
gs
> on teapots, I would never consider scoring the clay. No need. Wastes time=
.
>
> Is there a good technical argument for scoring?
>
> Best regards,
>
> Ivor Lewis,
> Redhill,
> South Australia
>
Vince Pitelka on wed 20 jan 10
Bob in Roseburg wrote:
"In a recent workshop with Steven Hill, he told us that scoring was
unnecessary when attaching two pieces of clay in which the clay platelets o=
n
both pieces have been made parallel by pulling or throwing. Both processes
align the clay particles parallel to the surface, and so they can form a
strong bond without scoring. However, when a handle is butted to the vessel=
,
the clay particles are aligned in different (perpendicular) directions, so
they need a scored junction, if the handle is to be strong. Extruded or sla=
b
sections also need scoring."
Bob -
I certainly recognize and respect Steven Hill's work and experience, but th=
e
first part above goes against all the logic of joinery. When the platelets
on two surfaces are parallel, it is all the more reason why you need to
score and slurry, unless you are actually working the two surfaces
aggressively together, wiggling and moving it back and forth to intermix th=
e
platelets. Otherwise, if the platelets along the joint are all parallel to
each other, it is a ready-made fracture plane.
When kids with no proper instruction just press two pieces straight togethe=
r
with no wetting or slurry, the clay seems to stick because of its surface
tackiness, but as the piece dries, it pops apart very easily. When clay is
pressed together this way, it flattens out all the platelets along the
joint, so that they are laying parallel, creating an ideal fracture plane.
The same is true with two slab pieces laying face to face - if they are jus=
t
pressed together, there is nothing joining them, and it is a perfect
fracture plane.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Randall Moody on thu 21 jan 10
-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of Jon Pacini
Sent: Thursday, January 21, 2010 3:52 PM
To: Clayart@LSV.CERAMICS.ORG
Subject: anyone attaching handles without scoring lines?
It's not that you can't make a box out of
stapled boards, but the dovetailed and glued one certainly will hold up
better and shows an understanding of craftsmanship. The same is true of sli=
p
and score.
Best regards
Jon Pacini
______
I would have to disagree with this premise. Scoring and slipping does not
mean that the handle will hold up any better and doesn't automatically poin=
t
to an understanding of craftsmanship. In fact it may point to an attitude o=
f
"I do this because I was shown/told to do this." Also, in Japan many of th=
e
old boxes were not glued at all. Granted they had ingenious systems of
joinery and pegging.
--Randall in Atlanta--
paul gerhold on thu 21 jan 10
Vince,
The question of the best way to join clay would make a great research effor=
t
for some college student or group of students. Talk about making a positiv=
e
contribution to clay. should be pretty simple to develop the methodology .
It's the time required that stops me.
Paul
On Wed, Jan 20, 2010 at 8:16 PM, Vince Pitelka wrote:
> Bob in Roseburg wrote:
> "In a recent workshop with Steven Hill, he told us that scoring was
> unnecessary when attaching two pieces of clay in which the clay platelets
> on
> both pieces have been made parallel by pulling or throwing. Both processe=
s
> align the clay particles parallel to the surface, and so they can form a
> strong bond without scoring. However, when a handle is butted to the
> vessel,
> the clay particles are aligned in different (perpendicular) directions, s=
o
> they need a scored junction, if the handle is to be strong. Extruded or
> slab
> sections also need scoring."
>
> Bob -
> I certainly recognize and respect Steven Hill's work and experience, but
> the
> first part above goes against all the logic of joinery. When the platele=
ts
> on two surfaces are parallel, it is all the more reason why you need to
> score and slurry, unless you are actually working the two surfaces
> aggressively together, wiggling and moving it back and forth to intermix
> the
> platelets. Otherwise, if the platelets along the joint are all parallel =
to
> each other, it is a ready-made fracture plane.
>
> When kids with no proper instruction just press two pieces straight
> together
> with no wetting or slurry, the clay seems to stick because of its surface
> tackiness, but as the piece dries, it pops apart very easily. When clay =
is
> pressed together this way, it flattens out all the platelets along the
> joint, so that they are laying parallel, creating an ideal fracture plane=
.
>
> The same is true with two slab pieces laying face to face - if they are
> just
> pressed together, there is nothing joining them, and it is a perfect
> fracture plane.
> - Vince
>
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka@dtccom.net; wpitelka@tntech.edu
> http://iweb.tntech.edu/wpitelka
>
David Finkelnburg on thu 21 jan 10
Paul,
I see you've gotten plenty of testimony that score/slip is not always a
requirement. An intelligent post, as usual, from Snail Scott argues that
score and slip is necessary under CERTAIN (not all) circumstances.
Industry virtually never uses score/slip with porcelain, but does use a
deflocculated attaching slip. With stoneware score and slip may be more
useful, but it's not a guarantee. I have found that if I add handles to
stoneware when it is pretty damp leather hard, almost too soft to hold its
shape while handling, then I don't need to score and I don't. A good
attaching slip is useful. The test, of course, is where the attachment
breaks.
Throw some test cylinders, attach handles, then at bone dry break them
off. If they break so that you see the original join clearly that's bad.
If the handle breaks or part of the cylinder wall pulls away but you can't
get it to break cleanly at the precise point of the join then you have a
good attachment. If your clay body and attaching process let you make those
kind of joins without score/slip then you can spend your time doing
something more fun! :-)
We make and sell an attaching slip. Scroll down at this link to read
about some experiences with it and two independent, unsolicited
evaluations. Pardon our enthusiastic advertising!
http://slipcast.blogspot.com/search/label/Stuck%20Up
A very serviceable attaching slip is made from a dry powder of a clay
body plus water and enough deflocculant to make the slip fluid at minimum
moisture content so shrinkage of the slip is minimized. For any dry clay
body the process is to add water and then deflocculant and mix well until a
minimum viscosity is reached. This is a slow process so be patient. Add a
single drop of deflocculant, mix very well over time to disperse it fully
and observe the result. Record the amount of deflocculant that just begins
to start to thicken the mix again. That is how you know you found the
minimum. Use that recipe for your clay body to make future batches.
Good potting!
Dave Finkelnburg
http://mattanddavesclays.com
From: Paul Borian
i stopped by the studio i used to work at yesterday and was watching a
potter put large handles on some really interesting pitchers, and i was
surprised that he did not use any scoring lines - he just put some slip on
there and attached the handles.....
Neon-Cat on thu 21 jan 10
Joins, cracks, and voids are studied by ceramic archaeologists and
students and there is quite a body of research available. Below is a
link to one research paper. It gives us a sort of backward look from a
microscopic level at the effects construction methods have on finished
work. This paper deals with Native American pottery sherd analysis.
"An Analysis of Voids in Ceramics", David Hill, Wichita State
University, Kansas, 1984, page 7 of document (page 1 of magazine):
http://soar.wichita.edu/dspace/bitstream/10057/1788/1/LAJ_16.1.pdf
Marian
Neon-Cat
Jon Pacini on thu 21 jan 10
Greetings all ---Vince wrote-"but the first part above goes against all the
logic of joinery"
I would like to introduce an analogy with woodworking joinery here---sure
you can staple a couple of boards together and call it a box or you can
dovetail and glue the joints. It's not that you can't make a box out of
stapled boards, but the dovetailed and glued one certainly will hold up
better and shows an understanding of craftsmanship. The same is true of sli=
p
and score.
Best regards
Jon Pacini
In rainy SoCal where I don't need to go white water rafting on the Colorado
with Joe--- I can go on Thompson Creek right here in Claremont today.
Vince Pitelka on fri 22 jan 10
Bob Johnson wrote:
"Vince: I think he assumed that the two pieces of clay to be joined (one of
his large "melon" pitchers and its handle) were of about the same moisture
content--and not too dry. It appeared to work for him.
As I said, I'm not an expert on this, but it seems to me that wet platelets
that are oriented in the same way are more likely to stick together as they
dry than if edges are impinging on flat surfaces. In any event, lots of
people on the list seem to be saying that scoring is not necessary, at leas=
t
under some conditions. But you'll have to talk to Steven to get more detail=
s
on his method and rationale. I'm not trying to dispute your experience or
knowledge, but just to pass on what I was taught at the workshop."
Bob -
Still doesn't make any sense, and at some point I'll ask Steven about it. =
I
recognize that scoring is not always necessary. The most important thing i=
s
to get the platelets to intermingle. Pressing two pieces with parallel
grain structure together is no better or worse than pressing them together
at 90-degree angles, but either will work fine if the platelets are
intermingled to lock the surfaces together. One way or another, that's
gotta happen. If both pieces of clay are very wet, I think that it happens
easily with minimal wiggling.
As an example, I teach my throwing students to make altered open bakers
where they throw a bottomless wall and set it aside, and then throw a
bottom, and stretch it into an oval. When both pieces are still very fresh=
,
they spray the bottom piece with some water, pick up the bottomless wall by
the close edge and let it distort, and then set it down on the ovaled
bottom. The water allows them to move the wall to the desired location.
Once it is in place, I just pick up the bat and tap it on the surface of th=
e
table a few times. We trim off the excess, and then run a metal rib under
the edges of the bottom piece, so that it presses up against the wall.
These never come apart as long as they are done when the pieces are freshly
thrown. That's about the only place I don't score and slurry, but I readil=
y
admit that my tendency to score and slurry is based on the fact that I was
taught that way, and it has always worked well for me. It takes little
extra time, so I think I'll stick with it.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
ivor & olive lewis on fri 22 jan 10
Dear Bob Johnson,
Accepting your hypothesis that clay becomes laminated through the alignment
of clay particles parallel to the surface of thrown or pulled items, what i=
s
it that ensures adhesion of one part to another ?.
It might be expected that Lawrence and West in their text book "Ceramic
Science for the Potter" (ISBN 0-8019-7155-1) would have an answer but
their diagrams indicate that all of the electrostatic forces that might
ensure adhesion are at the edges of the clay crystals, not across their
faces.
Under the term "Luting" in the Hamer Dictionary they suggest that wetting
the surfaces of leather hard clay re-plasticises the harder clay so that
"...they produce one piece when brought together with suitable pressure..."
Best regards,
Ivor Lewis,
Redhill,
South Australia
Bob Johnson on fri 22 jan 10
Ivor: I don't really have a position on this issue; I was just reporting
what I learned at Steven Hill's workshop. His view made sense to me, but it
could well be wrong.
Perhaps scoring does, in fact, make a stronger transition zone when a handl=
e
and a pot are of different degrees of wetness. Or maybe not. Perhaps it's
really the pressure and the increased plasticity of the joint, perhaps it's
some sort of microscopic entangling of clay particles, perhaps it has to do
with electrostatic forces on the edges of clay particles--or perhaps it's
just pottery lore. As someone suggested earlier, it is really an empirical
question for somebody's master's thesis. My guess, however, is that you
would agree that a pot that is thrown properly--and hence has the particles
aligned in parallel in the walls--will be stronger than a pot made of gobs
of clay that are stuck together without being so aligned.
Bob
-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of ivor & olive
lewis
Sent: Thursday, January 21, 2010 7:37 PM
To: Clayart@LSV.CERAMICS.ORG
Subject: Re: anyone attaching handles without scoring lines?
Dear Bob Johnson,
Accepting your hypothesis that clay becomes laminated through the alignment
of clay particles parallel to the surface of thrown or pulled items, what i=
s
it that ensures adhesion of one part to another ?.
It might be expected that Lawrence and West in their text book "Ceramic
Science for the Potter" (ISBN 0-8019-7155-1) would have an answer but
their diagrams indicate that all of the electrostatic forces that might
ensure adhesion are at the edges of the clay crystals, not across their
faces.
Under the term "Luting" in the Hamer Dictionary they suggest that wetting
the surfaces of leather hard clay re-plasticises the harder clay so that
"...they produce one piece when brought together with suitable pressure..."
Best regards,
Ivor Lewis,
Redhill,
South Australia
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.432 / Virus Database: 271.1.1/2637 - Release Date: 01/21/10
19:34:00
ivor & olive lewis on fri 22 jan 10
Interesting notion Ron. But if clay becomes over dry for the instant, none
scoring, method to be successful then it may pay to re-asses studio
practice.
One of the concepts that comes to light from time to time is that clay is
hydrophobic. It is an idea I have never been able to understand, except in
the sense that clay minerals are insoluble in water.
Good to hear from you again.
Sincere regards,
Ivor
Ivor Lewis,
Redhill,
South Australia
Subject: Re: anyone attaching handles without scoring lines?
My understanding is - if the clay gets too hard - scoring helps to re
wet it. The scoring should be wiped out before joining - no point in
having air in the joint.
RR
Quoting ivor & olive lewis :
> Dear Paul Borian,
> Is there a good technical argument for scoring?
>
> Ivor Lewis,
> Redhill,
> South Australia
ivor & olive lewis on sat 23 jan 10
Dear Bob Johnson,
Yes, some dedicated research would resolve this issue. As you rightly point
out, mechanical work appears to enhance the durability of raw clay objects.
Some rapidly made coiled pots are prone to spontaneously self destruct.
Best regards,
Ivor Lewis,
Redhill,
South Australia
David Woof on sun 24 jan 10
We have this scoring vs/vs topic about once a year. This time ..... There=
=3D
were many persuasive pros and cons=3D2C and a few suppositions based on mi=
s-=3D
applied known science.=3D20
As with so many things=3D2C no definitive answer is readily apparent=3D2C s=
o ea=3D
ch is left to consider and trusted to make an informed ethical decision. It=
=3D
is an important issue and not just from personal preference or technical a=
=3D
rgument. =3D20
=3D20
We better have it right=3D2C especially if we present ourselves as experts =
an=3D
d give information to perhaps new=3D2C naive and trusting souls in workshop=
s =3D
and publications. The buying public becomes the recipient of our research =
=3D
and ultimately the tragedies of our error.
=3D20
What I am left with and always come back to is: I score=3D2C not because I=
a=3D
m blindly and unthinkingly following my first teacher but because I know it=
=3D
works no matter what type and character of clay I happen to be using. =3D2=
0
=3D20
I do not work as a purist out of the bag. I mix it up=3D2C add native clay=
s =3D
for effects=3D2C throw in some of this and that to get the character I am a=
ft=3D
er so "knowing My materials" takes on a different meaning for me.=3D20
=3D20
I will do my best not risk a handle coming off because somewhere someone so=
=3D
aked=3D2C dish washed and micro waved or froze the hell out of it and the s=
ep=3D
aration could be=3D2C by opinion of hired ceramic engineer=3D2C argued as i=
mpro=3D
per attachment. And not of least concern=3D2C my concern for the trusting =
cu=3D
stomer/patron who gets a cupa hot in the lap or on the nursing baby and a d=
=3D
eep feeling of betrayal amid the trauma and scars.
=3D20
Also I like the "love of the process"=3D3B this wee bit of "love play" dia=
lo=3D
gue that goes on with the clay and the whole process of bringing the mug or=
=3D
pouring vessel into being. Slow down and give this vessel=3D2C this form=
=3D2C=3D
this moment=3D2C that intimate individual attention. It may seem just to =
be=3D
an unnecessesary token but it can keep us focused on why we do this at all=
=3D
and the real person-ness of our customers as well as our reputation as a t=
=3D
rusted professional.=3D20
=3D20
I've copied (see below) part of a post James F wrote that I think represent=
=3D
s one of many level headed responses to the information provided in the cur=
=3D
rent run on this topic.=3D20
=3D20
Best to all=3D2C
=3D20
David Woof Clarkdale=3D2C Arizona
=3D20
Ivor=3D2C Rimas=3D2C et alii... from James
In this context=3D2C I believe one must consider the flocculatory effect of=
t=3D
he
acetic acid in the vinegar. It is a common observation that breaks in
greenware repaired with water typically fail=3D2C while breaks repaired wit=
h
vinegar often survive. Vince pointed out (quite correctly) in another post
that a mechanical bond is necessary between joined clay parts. Such bonds
can occur on the microscopic scale between clay platelets (the Velcro
principle)=3D2C or on a macro scale (which is the reason for=3D2C and justi=
fica=3D
tion
of=3D2C scoring). In dried greenware=3D2C or even leatherhard clay=3D2C the=
plate=3D
lets
become more densely packed=3D2C and especially where the surface has been
worked=3D2C are probably approaching a tightly packed "card stack" structur=
e.
Though vinegar is indeed mostly water=3D2C the acid constituent should oper=
at=3D
e
to flocculate the clay at the surface=3D2C giving it a "house of cards" (ra=
nd=3D
om)
structure (see Hamer=3D3B flocculation). This open "house of cards" structu=
re
makes a mechanical interlock between the parts more probable=3D2C and there=
fo=3D
re
makes the join more likely to survive until sintering=3D2C and ultimately t=
he
glassy phase of full temperature firing=3D2C renders the piece monolithic.
Just my thoughts.
=3D20
_________________________________________________________________
Hotmail: Powerful Free email with security by Microsoft.
http://clk.atdmt.com/GBL/go/196390710/direct/01/=3D
| |
|
