Vince Pitelka on thu 27 jun 96
Corinne -
The difference between an engobe and a slip is that an engobe is formulated
with less clay content than a slip. In essence, it is a cross between a slip
and a glaze. With a lower percentage of clay, it has a higher percentage of
silica and flux, and therefore shrinks less in drying on the bone-dry or
bisque-fired pot. A slip, when applied to damp wares, shrinks WITH the wares
as they dry. A slip formulated for application to dry or bisque wares (an
engobe) must not shrink excessively. Also, the higher percentage of flux in an
engobe helps it to bond to the surface in the firing. A slip bonds to the
surface due to the interlocking of the platelates on the interface between the
damp clay and wet slip.
If you have a slip which has also been working as an engobe, chances are that
it is in fact an engobe recipe. Most engobes will work when applied to damp
clay, as well as with bone-dry and bisque-fired clay. If you are using a slip
made from your clay body, then you have been lucky not to have experienced
separation. If you are using your slip quite thin, then it is not so
surprising. But most ordinary slips, if applied thickly to bone-dry or
bisque-fired wares will flake off in the drying or firing.
- Vince
Vince Pitelka - wkp0067@tntech.edu
Appalachian Center for Crafts, Smithville, TN
Valice Raffi on fri 28 jun 96
>----------------------------Original message----------------------------
But most ordinary slips, if applied thickly to bone-dry or
>bisque-fired wares will flake off in the drying or firing.
> - Vince
I am looking for an engobe, or slip recipe that WILL flake. I don't want
all of it to fall off, just some (I go for the "ancient" look!) Can
anybody help?
I use IMCO Sculpture Mix 412, fired To ^6, electric.
TIA, Valice
gail@matra.com.au on sat 29 jun 96
>----------------------------Original message----------------------------
>I am looking for an engobe, or slip recipe that WILL flake. I don't want
>all of it to fall off, just some (I go for the "ancient" look!) Can
>anybody help?
>
>I use IMCO Sculpture Mix 412, fired To ^6, electric.
>
>TIA, Valice
>
>
Valice,
I have developed a range of slips (for application at plastic or leather
hard stage) with just this quality in mind....I like the slip to just begin
to fall off, but not all the way...gives great textural effects in soda firing.
I'd suggest starting with whatever slip you have that already fits your
body, and change the clay content to a less plastic one. eg use kaolin
instead of ball clay. It will take some experimentation, and possibly some
addition of bentonite (if you get too much flaking) to adjust the shrinkage
rate to get just the right degree of "non-fit".
Another alternative is apply your slips at the dry stage (assuming your
present slips fit well at leather hard stage). If you spray the slip onto
dry ware, allowing the slip to dry slightly between coats, you will actually
see fine crack lines appearing in the slip surface. This usually means
you've reached the desired thickness of application for the slip to begin to
peel off during firing.
..............................................................
Gail Nichols gail@matra.com.au
SODA GLAZE CERAMICS http://www.matra.com.au/~gail/
Sydney, Australia
..............................................................
Denise Philipbar on mon 14 jan 02
Martin,
Slip is actual clay mixed or not with colorants. The Engobes I use are
generally halfway between slip and glaze. I use them as both =
underglazes
and overglazes. I can use slip on the bottom of a pot without worrying =
that
it will stick to the kiln shelf, but engobes flux more and will stick.
However, engobes don't flux enough to be used on their own without a
glaze...they tend to have a more matte surface than a glaze but not as =
matte
as a slip. =20
I think that the same engobe I use at ^10 may really be a slip at a =
lower
temperature.
I hope this helps,
Denise
-----Original Message-----
From: Martin Rice [mailto:martin@rice-family.org]
Sent: Monday, January 14, 2002 2:09 PM
To: CLAYART@lsv.ceramics.org
Subject: Slip vs Engobe
Hi,
I just joined this list today and am a rank beginner. I live in the =
jungle
in Costa Rica and am going to have to be completely self taught. I just
bought an ancient kick-wheel in San Jos=E9 where the only kind of wheel =
and
kiln one can buy is used (it would cost way too much for me to import =
them)
and I used it for the first time just a little while ago.
I'm more than willing to pay my dues while learning -- I always have. =
So
I'll keep consulting the books I've bought and plug ahead.
My immediate question, however, has to do with slip and engobe. The =
books
I'm reading are in Spanish and, although I'm a linguist by trade, I've =
only
been working with Spanish for about a year. I thought that I had it all
figured out: slip in English =3D engobe in Spanish. Then, today looking =
at
some material on the web, I saw both slip and engobe referred to on an
English language site.
I'd really appreciate it if someone could explain the difference =
between
them and their respective purposes for me.
Thanks so much,
Martin
________________________________________________________________________=
____
__
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You may look at the archives for the list or change your subscription
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Moderator of the list is Mel Jacobson who may be reached at
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Anne Wellings on thu 17 jan 02
I have found that slip and engobe recipes will flux more according to the
colorant and amount of colorant added, because the coloring oxides can act
as fluxes, especially red iron oxide and cobalt oxide, and maybe manganese.
I have a ^6 black slip (or engobe) recipe with cobalt and manganese that
fluxes so much that it looks like a glaze. Maybe it is the manganese that
is doing it and not the cobalt. It is very attractive with sgraffito
decorating. If anyone wants it, I will post it.
I have been getting my Clayart Index a few days late on a regular basis,
for the last 2 weeks or so. So my responses to posts may be out of date.
Juno has not been of any help on this. Is anyone else having this problem?
If it keeps up, I will switch my clayart to a Yahoo mailbox. My Clayart is
the only mail that I am having this trouble with. Weird.
Anne
On Mon, 14 Jan 2002 17:11:05 -0700, Denise Philipbar
wrote:
>Martin,
>
>Slip is actual clay mixed or not with colorants. The Engobes I use are
>generally halfway between slip and glaze. I use them as both underglazes
>and overglazes. I can use slip on the bottom of a pot without worrying
that
>it will stick to the kiln shelf, but engobes flux more and will stick.
>However, engobes don't flux enough to be used on their own without a
>glaze...they tend to have a more matte surface than a glaze but not as
matte
>as a slip.
>
>I think that the same engobe I use at ^10 may really be a slip at a lower
>temperature.
>
>I hope this helps,
>Denise
>
>
>-----Original Message-----
>From: Martin Rice [mailto:martin@rice-family.org]
>Sent: Monday, January 14, 2002 2:09 PM
>To: CLAYART@lsv.ceramics.org
>Subject: Slip vs Engobe
>
>
>Hi,
>
>I just joined this list today and am a rank beginner. I live in the jungle
>in Costa Rica and am going to have to be completely self taught. I just
>bought an ancient kick-wheel in San Jos=E9 where the only kind of wheel and=
>kiln one can buy is used (it would cost way too much for me to import them)=
>and I used it for the first time just a little while ago.
>
>I'm more than willing to pay my dues while learning -- I always have. So
>I'll keep consulting the books I've bought and plug ahead.
>
>My immediate question, however, has to do with slip and engobe. The books
>I'm reading are in Spanish and, although I'm a linguist by trade, I've only=
>been working with Spanish for about a year. I thought that I had it all
>figured out: slip in English =3D engobe in Spanish. Then, today looking at
>some material on the web, I saw both slip and engobe referred to on an
>English language site.
>
>I'd really appreciate it if someone could explain the difference between
>them and their respective purposes for me.
>
>Thanks so much,
>Martin
>
>___________________________________________________________________________=
_
>__
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
>
>___________________________________________________________________________=
___
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Kate Johnson on fri 18 jan 02
Anne wrote:
I have found that slip and engobe recipes will flux more according to the
colorant and amount of colorant added, because the coloring oxides can act
as fluxes, especially red iron oxide and cobalt oxide, and maybe manganese.
I have a ^6 black slip (or engobe) recipe with cobalt and manganese that
fluxes so much that it looks like a glaze. Maybe it is the manganese that
is doing it and not the cobalt. It is very attractive with sgraffito
decorating. If anyone wants it, I will post it.
And yes, please, I'd like very much to see it...I am a newborn baby when it
comes to glazes/slips/engobes but this sounds lovely. I've been very
interested in sgraffito and slip trailing but haven't tried it yet--other
than one experiment of scratching through a commercial glaze. It was just
marginally successful enough to make me want to do more.
Thanks!
Best--
Kate
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