search  current discussion  categories  kilns & firing - raku 

smoke resist slip for raku

updated thu 29 nov 01

 

Winston J. Taylor on mon 26 nov 01


Fellow potters,
I am looking for a recipe for the slip that when applied to bisque and
fired in raku kiln produces the black smoke trails after the slip is scaled
off. I had such a recipe and lost it.
thanks, Winston J. Taylor

Imzadi D. on tue 27 nov 01


In a message dated 11/26/01 9:04:23 PM Pacific Standard Time,
Not sure if this is what you are looking for, but I found this site that
looks like an interesting process for raku but have not tried it.

http://www.geocities.com/SoHo/Cafe/3755/jadetech.html

Imzadi


Winston_taylor@HOTMAIL.COM writes:

<< Fellow potters,
I am looking for a recipe for the slip that when applied to bisque and
fired in raku kiln produces the black smoke trails after the slip is scaled
off. I had such a recipe and lost it.
thanks, Winston J. Taylor >>

Charlie and Linda Riggs on tue 27 nov 01


Hi Winston,

Here is a formula I first saw used by Gordon Hutchins.

Fire Clay………………. 5 parts
EPK…………………… 3 parts
Alumina Hydrate……… 1-2 parts

More alumina hydrate is used to enable the slip to “stick” to the pot better and is
subtracted from the recipe if you need it to fall off more easily.

The ingredient that seems most crucial for easy slip removal is the type of fire
clay. The secret is that not all fireclays are created equal. Cedar Heights Gold
Art Fire Clay, which is a commonly available fireclay, is a very smooth fine mesh
fire clay, which adds plenty of shrinkage and tends to help the slip fall off the
piece easily. Other fire clays such as North American Fire Clay are non-plastic
and would have the opposite effect.

We revised his recipe as follows using two different fire clays for maximum
adherence to the pot during firing,
yet easy to remove after the post-firing reduction.


Cedar Heights Fire Clay……… 5 parts
Paco Fire Clay………………... 5 parts
EPK…………………………... 6 parts
Alumina Hydrate……………... 4 parts

This recipe takes advantage of the shrinkage of the Cedar Heights fire clay and the
coarse less plastic nature of Paco fireclay.

If you only have Cedar Heights Fire Clay you might try “pre-shrinking” some of the
dry powered clay before adding it to the mix. Just place a portion into a bisque
firing and then substitute a portion of the original fire clay with the pre-fired
or calcined fire clay.

A good starting point might be:

Cedar Heights Fire Clay……………. 4 parts
Cedar Heights Fire Clay (calcined)… 1 part
EPK………………………………… 3 parts
Alumina Hydrate…………………… 2 parts

Note that most everyone will need to make some adjustments to their naked raku
formula. Pots that are not burnished will need a slip that will come off much
easier. Highly burnished pieces will need a formula that will adhere better.

Fire to a maximum of 1600 degree F. Any hotter and the slip will be hard to
remove.

Linda




"Winston J. Taylor" wrote:

> Fellow potters,
> I am looking for a recipe for the slip that when applied to bisque and
> fired in raku kiln produces the black smoke trails after the slip is scaled
> off. I had such a recipe and lost it.
> thanks, Winston J. Taylor
>
> ______________________________________________________________________________
> 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.

WALLY ASSELBERGHS on wed 28 nov 01


Winston,

6 parts kaolin
4 parts flint (or quartz)

or

5 parts fat stoneware clay
3 parts kaolin
2 parts flint (or quartz)

10% cupperoxyde can be added to either of both recipes, if you like the =
feeling
to jump with a blindfold.

I normally use these mixtures as "separation sliplayer" for my "naked =
raku", but they
also give great results with "smoked raku"
First recipe gives more "contrast", sharper edges, second receipt gives =
shady part between
areas covered with slip, and areas left blank.
Be sure to sift them thoroughly through 100mesh-sieve prior to use.

Good luck,
Wally from Flanders, where the last birds have now gone, spreading their =
wings above the
highways to the south.
wally.asselberghs@pi.be

ORIGINAL Message:=20
Date: Mon, 26 Nov 2001 21:02:34 -0500
From: "Winston J. Taylor"
Subject: smoke resist slip for raku
Fellow potters,
I am looking for a recipe for the slip that when applied to bisque and
fired in raku kiln produces the black smoke trails after the slip is =
scaled
off. I had such a recipe and lost it.
thanks, Winston J. Taylor

_________________________________________________________________________=
_____