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: re: underglaze

updated tue 13 may 03

 

iandol on sat 10 may 03


Dear Friends,

I am becoming confused about the descriptions which are being given for =
various ways of applying stains and colouring oxides. Ababi has just =
given us his recipe and technique for creating Majolica decoration =
suggesting that the colourant be mixed with a high proportion of Gerstly =
Borate. Perhaps I am missing the point but this is a rather reactive =
flux. I would predict that it will have had a negative effect on the =
opaque glaze on which the stains were being used, causing excessive flow =
which will destroy the clarity of the image which was intended on the =
surface of the clay.

If the colour has to be diluted to one quarter of its strength, why =
cannot the supportive glaze be used? If pale tones are needed, then =
using an adhesive organic vehicle which suspends the pigment seems to be =
the most appropriate carrier. So we fall back on plant gums for adhesion =
and Glycerine to improve flow from the brush

Alternatively. If it is Underglaze decoration we are discussing, I would =
not use such a strong flux which has such a low fusion point to create =
an image which will be visible through a transparent glaze. The effect =
here is to seal the clay with an impervious layer which will prevent the =
glaze from adhering to the pot. The underglaze image has to remain =
porous so that glaze will suck onto the bisque when it is applied. If =
glaze is prevented from adhering there will be bare patches on the work. =
In this case, if a dilutant is needed then slip with the same =
constituents as the underlying clay will suffice.=20

Best regards,

Ivor Lewis.

OWLPOTTER@AOL.COM on mon 12 may 03


In a message dated 5/11/2003 10:57:19 PM, iandol@TELL.NET.AU writes:

<< I am becoming confused about the descriptions which are being given for
various ways of applying stains and colouring oxides. Ababi has just given us
his recipe and technique for creating Majolica decoration suggesting that the
colourant be mixed with a high proportion of Gerstly Borate. Perhaps I am
missing the point but this is a rather reactive flux. I would predict that it
will have had a negative effect on the opaque glaze on which the stains were
being used, causing excessive flow which will destroy the clarity of the
image which was intended on the surface of the clay... Ivor Lewis.>>

I use Mason Stains and OLD Gerstley Borate (60:40 ratio) mixed with water to
a milk consistancy, then add a few drops of glycerin (from the drug store.)

I use this mixture to paint over a white unfired glaze, using a Sumi-e brush
technique learned in a oriental painting class.

I then fire the pots to cone 8 or 9 in my electric kilns.

I find that there is no negative effect on my opaque glaze. No flow
whatsoever.

What I really love about this technique (which Ababi says is "Majolica") is
that the color of the stain mixture in the jar is the exact color I get on
the pots. And these colors can be blended (before applying) to get any
shade I want, so the pallette is endless.

See examples of my work at Chris's website:
http://www.lightonecandle.com/clayartgallery.html

and at my old website: geocities.com/owlartstudio

-Carolynn Palmer, Somerset Center, Michigan