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slips and claybodies.

updated fri 17 oct 03

 

Norman van der Sluys on mon 13 oct 03


If ever I start a potter's supply business (not likely) I now have a
name for it :0)

Lee Love wrote:
>
> ----- Original Message -----
> From: "Lee Love"
>
> > fireclay bodies I used back home from MN Clay and Congenital Clay.
>
> *Haha!* Sorry Continental Clay! My spellchecker "hambergered" the name.
> ;^)

--
Norman van der Sluys
Benona Pottery
Near the shore of Lake Michigan still fighting the good fight against
the ladybugs, maybirds, or whatever.

Lee Love on mon 13 oct 03


----- Original Message -----
From: "Ron Roy"

> Beware the suggestion of using an iron slip over a white body - I'm not
> saying it isn't possible but the slip could have cristobalite after firing
> and having a glaze and two kinds of clay fighting each other can be a
> nightmare.

Of course, Ron is speaking "theoretically." :^) In the tens
of thousands of Mashiko pots I've seen fired in the Noborigama: Mashiko nami
tsuchi, with an ocher slip, I've never seen dunting problems.

>Proper fit testing for compatibility of the body, slip and glaze are
mandatory.

Testing is always a good idea, especially when you are working with
non-industrial materials that you cannot be sure of an analysis to put into
a formula or calculation program.

I went to the Osaki Jinja (shrine) flea market with Jean and
Taiko yesterday. I held two fine examples of this type of work made by
Shoji Hamada, some really fine matchawa that are a good example of this
slipped technique. I really get a kick out of these bowls because before
Hamada, nobody ever considered making tea ceremony objects out of lowly
Mashiko clay. I'll put up some photos soon.

The best examples of Hamada's work are often underfired and
never would pass absorption or other test industrially inspired people tell
us we must lock-step to. Sometimes you have to set your priorities. If
you look at the work made by these too approaches you can see the obvious
differences. I will not say that only one way should predominate as
others suggest. But if someone doesn't speak up for the non-industrial
way, it will certainly disappear.

The woman who had this work at her booth, along with my
teacher's work is related to Sudo Sensei, a contemporary of Shoji Hamada's.
There were several great potters: Sudo, Murata Gen, Goda, Kimura and
Sakuma,j working at the same time as Hamada here in Mashiko, but are not
well known back home, because they existed in Hamada's shadow. There is a
substantialness in the work from this time that is pretty much lost today.
I'm not sure how or why the "feeling" has been lost, but I think some of it
is related to a more industrial mindset in modern potters.

Just for clarification: iron bearing slip is not applied to a
white body. This would be a waste of good porcelain or white stoneware.
While Mashiko Nami Tsuchi is light colored, it is not white. It has a high
silica content. Often, the glaze put over the claybody and slip is also of
high silica content, whether it be Nuka or Kaki glaze, but ocher slip is
also use with the standard nami shiro (half ash, half ball clay) and also
with temmoku, or kuro ame (an Ame, amber glaze that has iron added to make
it black My teacher's black is kuro ame.) There is no problems with
either type of glazes, or, when there are "technical problems", they are
esthetically desired. Hamada's museum is full of these "technically
flawed" esthetic beauties!

Slip applications are usually pretty thin, thinner than glaze
applications. You are more likely to have a cristobalite problem related
to the thickness of an iron bearing glaze than you are an iron bearing slip.
And the traditional slip here in Mashiko is 100% ocher clay, nothing else
added, unlike what I used back home which was only 10% ocher added to a base
slip. It burns very metallic where it is bare.

For my own slip, I've added some of my hakame slip to cut the
ocher. Also, what I mention about coating the foot and doing inlay in on
the wirecut bottoms: I use a slip made of an iron bearing clay body (it is
made of my teacher's clay body, some that was being thrown out because of
some iron spotting it was doing, which is not acceptable for his zogan
inlay.) His iron clay body is similar in color to the iron colored
fireclay bodies I used back home from MN Clay and Congenital Clay.

--
Lee In Mashiko, Japan
http://Mashiko.org
Web Log (click on recent date):
http://www.livejournal.com/users/togeika/calendar

Lee Love on mon 13 oct 03


----- Original Message -----
From: "Lee Love"

> fireclay bodies I used back home from MN Clay and Congenital Clay.

*Haha!* Sorry Continental Clay! My spellchecker "hambergered" the name.
;^)

--
Lee In Mashiko, Japan
http://Mashiko.org
Web Log (click on recent date):
http://www.livejournal.com/users/togeika/calendar

Ron Roy on wed 15 oct 03


I have made this point before but it is important to keep in mind.
Traditional potters - using local materials have already gone through the
testing phase - they know what works because their ancestors found out the
hard way.

We - on the other hand - are like children in a candy store - an unlimited
supply of materials, clay bodies and glazes. And we usually have no idea
about the expansions of any of them - we simply try what we like and hope
that it works.

Any kind of slip - and especially high fire Iron bearing slips can be a
real nightmare - best to make em into clay and test them with our glazes.
If they work OK with the glazes then you can be pretty sure they will be OK
if those same glazes work on our other clays.

RR

>----- Original Message -----
>From: "Ron Roy"
>
>> Beware the suggestion of using an iron slip over a white body - I'm not
>> saying it isn't possible but the slip could have cristobalite after firing
>> and having a glaze and two kinds of clay fighting each other can be a
>> nightmare.
>
> Of course, Ron is speaking "theoretically." :^) In the tens
>of thousands of Mashiko pots I've seen fired in the Noborigama: Mashiko nami
>tsuchi, with an ocher slip, I've never seen dunting problems.
>
>>Proper fit testing for compatibility of the body, slip and glaze are
>mandatory.
>
> Testing is always a good idea, especially when you are working with
>non-industrial materials that you cannot be sure of an analysis to put into
>a formula or calculation program.

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

Lee Love on wed 15 oct 03


----- Original Message -----
From: "Ron Roy"



> I have made this point before but it is important to keep in mind.
> Traditional potters - using local materials have already gone through the
> testing phase - they know what works because their ancestors found out the
> hard way.

Yes.

> We - on the other hand - are like children in a candy store - an unlimited
> supply of materials, clay bodies and glazes. And we usually have no idea
> about the expansions of any of them - we simply try what we like and hope
> that it works.

We have to make self-imposed limitations, for creative focus. I
feel very fortunate in that I began in a a tradition in Minnesota. Lotsa
groundwork done, begining in the early part of century. If you have good
teachers and the right attitude, you don't have to re-create the wheel.

> Any kind of slip - and especially high fire Iron bearing slips can be a
> real nightmare - best to make em into clay and test them with our glazes.
> If they work OK with the glazes then you can be pretty sure they will be
OK
> if those same glazes work on our other clays.

Back home, what I did for my iron slips was use the iron bearing
claybody I used from Continental Clay or Minnesota Clay. It become really
important for me, when Minnesota Clay stopped making their Minnesota
Indigenous Clay stoneware body. (too many people complained about popouts.
They never effected my work.) They only made test runs and when they
stopped, I bought several boxes worth from a friend who was testing it.
Instead of using it as a clay body, I made it into a slip and coated both my
stoneware body and the raku body I liked to use in woodfire. I still have
a couple boxes back home, in storage. Probably hard as bricks.

But it really is a common sense way to make a slip, use it on the
same body, but without iron, and have a good chance of success. It is much
more versatile than having the iron in the clay body and you end up having
fewer problems, especially firing in a large wood fired kiln. You solve
many problems firing a traditional wood kiln by asking what was
traditionally used in the kiln.

--
Lee In Mashiko, Japan
http://Mashiko.org
Web Log (click on recent date):
http://www.livejournal.com/users/togeika/calendar

Ron Roy on thu 16 oct 03


I was never satisfied with what I "found" - had to make my own to get
satisfaction. Not so much reinventing the wheel but a case of building up
the skills that I needed to get what I wanted.

I don't have to use those skills all the time but it sure is handy to have
em when I need em.

The fact that some materials will go out of production - it happens all the
time - is another argument for being able to duplicate a clay or a glaze.
Not always possible I suppose but that depends on other factors in the long
run.

Creative focus can take many forms - the more forms you have the better the
chances of making it your own.

RR


> We have to make self-imposed limitations, for creative focus. I
>feel very fortunate in that I began in a a tradition in Minnesota. Lotsa
>groundwork done, begining in the early part of century. If you have good
>teachers and the right attitude, you don't have to re-create the wheel.

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513