Marianne Lombardo on tue 8 oct 02
I'm trying to figure out how people apply underglaze or oxides to
engraved/carved/scraffito areas on pots, and then wipe it off, leaving the
coloring in the engraved/carved areas only.
When I attempt to do this on porcelain bisque, the entire pot is stained
with the colorant. And yet I have *seen* pots that people have done this to
and the sponged away area is nice and white, not streaky and smeary.
Can anyone advise? This is getting frustrating. I keep wrecking nicely
carved work.
I thought of applying the underglaze when the pot is still greenware and
then sponging it off, but I think that will remove a lot of the delicate
detail in the carved areas.
Help, please?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
Jeff Longtin on wed 9 oct 02
Marianne,
Apply a few coats of wax resist to your greenware pots, allow to dry, then
carve your design. Then fill the design with a colorant. Then wipe away the
excess slip/colorant with a wet sponge.
Chances are likely the slip will remain wet on the wax resist but be dry in
the carvied areas. This should make it easy to sponge away the excess slip.
The wax resist does a nice job of protecting the clay surface from the
colorant and it also protects the pot from the water in your sponge (be
careful though).
The wax resist burns out in the bisque so you can glaze as normal.
Have fun.
Jeff Longtin
May Luk on wed 9 oct 02
Hi Marianne;
You might want to try;
1-Lay a coat of wax resist before carving (try it when the clay is very soft
or bone dry depending on your technique)
2-Use slip trailer or a brush to add colour more precisely. Slip trailer is
quite fun cause the solution runs inside the gutter, rotate the piece and
let the colour flow.
3-When the stain is dried, clean up the edges with a knife lightly, if
needed. Do not wipe/brush off the excess. Use a vaccum cleaner so that it
doesn't smear by moving stains around.
4-After bisque fired, different stains behaves differently; I add another
coat carefully if the colours are weak, or I sand away the stained area.
Once again, use the vaccum cleaner to clean up.
I do this with earthenware, hope this help with porcelain.
Best regards
May Luk
London, UK
on 10/9/02 12:58 am, Marianne Lombardo at mlombardo@NEXICOM.NET wrote:
> I'm trying to figure out how people apply underglaze or oxides to
> engraved/carved/scraffito areas on pots, and then wipe it off, leaving the
> coloring in the engraved/carved areas only.
>
> When I attempt to do this on porcelain bisque, the entire pot is stained
> with the colorant. And yet I have *seen* pots that people have done this to
> and the sponged away area is nice and white, not streaky and smeary.
>
> Can anyone advise? This is getting frustrating. I keep wrecking nicely
> carved work.
>
> I thought of applying the underglaze when the pot is still greenware and
> then sponging it off, but I think that will remove a lot of the delicate
> detail in the carved areas.
>
> Help, please?
>
> Marianne Lombardo
> Omemee, Ontario, Canada
> email: mlombardo@nexicom.net
>
>
Paula Sibrack Marian on wed 9 oct 02
Marianne, What you are describing is incised decoration. (Sgrafitto needs to be scratched through an underglaze before bique fire.) Try incising a design in greenware. Then apply undergalze or slip with a small brush or a slip trailer. If any gets on the surface of your porcelain, you can lightly scrap it off. I wouldnn't wash it, as it could begin to slake down the clay surface.Good luck, Paula Sibrack Marian, in the woods of Sherman
Snail Scott on wed 9 oct 02
At 08:58 PM 10/8/02 -0400, you wrote:
>I'm trying to figure out how people apply underglaze or oxides to
>engraved/carved/scraffito areas on pots, and then wipe it off, leaving the
>coloring in the engraved/carved areas only.
>When I attempt to do this on porcelain bisque, the entire pot is stained
>with the colorant...
1- try bisquing higher.
2- try moistening the bisque first.
-Snail
Maid O'Mud on wed 9 oct 02
May Luk said in part:
3-When the stain is dried, clean up the edges with a knife lightly, if
needed. Do not wipe/brush off the excess. Use a vaccum cleaner so that =
it
doesn't smear by moving stains around.
DON'T VACUUM dry clay ever!! You will spread micro silica particles =
all over. This IS dangerous.
sam
Marianne Lombardo on thu 10 oct 02
Thanks to all who responded about trying to remove colorant from bisque,
after washing with underglaze. Someone suggested firing the bisque higher
and I haven't tried that yet. So far, taking the bisque outdoors and
lightly sanding it seems to work, but it's time-consuming and somewhat
messy. I think I'll finish the ones I have started and then abandon this
until later.
This isn't carving, but a nice technique for slab dishes is to take some
tiny delicate cedar branches (I think it's cedar, flat green needles) and
lay them out on a slab and roll them in. Then take the end of a brush and
press in some groupings of "berries", add a few curly squiggles with a
scraffito tool. Freeform drape it over something shallow, add a foot with
slip. Looks nice and kind of wintry/Christmasy, even though I guess cedars
don't really have berries (who cares, artistic license ).
This is one of the pots I wanted to rub green underglaze into the
depressions and color the berries red, leaving the rest of the pot white.
Unfortunately, I want white, not green smeared white. Oh well. I guess
I'll have to sand these to get what I want.
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
Culling on thu 10 oct 02
> I thought of applying the underglaze when the pot is still greenware and
> then sponging it off, but I think that will remove a lot of the delicate
> detail in the carved areas.
I do my carving by painting the design on with shellac and then wiping
back - etching the surface, add more shellac to resist more and get
different depths etc thn it's imple to put on and wipe off underglaze at he
end (all done at leather hard) maybe if you put shellac on before you
carve?...
Steph
Warm dry North West Western Oz
Susan Giddings on fri 11 oct 02
Marianne,
I read the other responses to this dilemma and when you described what
you wanted to do, I thought I would share this with you. It may be easier.
But first of all, let me say that it is a somewhat time consuming process
but the results, I think will satisfy what you're looking for.
The technique I learned from a workshop I took with Mary Barringer 3-4
years ago.
Make your slab and impress whatever design you want. (The cedar branches,
twigs, berries and leaf curlyques.)
Let it dry to pretty firm leather hard.
Mix mason stains to slip of the same clay body (in this case porcelain but
it really doesn't matter) Mix to color by eye. You can also use coloring
oxides but these can't be mixed "by eye" and expect to achieve the right
color!
Brush colored slip over and into the impressed design.
Let this dry until firm leather hard again.
Using a stainless steel thin, flexible rib, carefully scrape over the
designs. The angle of the rib is a key - you want it to be pretty shallow -
not necessarily 90 degree direct vertical. The more vertical it is, the
more careful you have to be about gouging the slab. However, if the slab is
really dry, you may find that a more vertical angle will give you the best
results. Use the flexibility of the rib to help you scrape the slip off.
If the design you've impressed is very deep, you may need to add more
layers of colored slip. You don't need to add more over the WHOLE piece if
only one area needs it. Just add more where it is needed.
I have found that I can scrape a 12"- 14" sqaure slab (porcelain -
stoneware with grog seems to take a bit longer) in less than 1/2 hour but
it really has to be very firm leather hard. If it's too soft, the colored
slip will smear. NOT TO WORRY IF IT DOES - just wait until it's a bit drier
and scrape it off then.
This is actually very easy to do and not at all really time consuming if
the slab is at the right state of dryness and the impressed design is
fairly straightforward. Sometimes I've used a big wooden rib to start with
to get the worst of the overslip off, then resorted to the flexible
stainless steel rib to finish the cleanup. I'd encourage you to play around
with this technique a bit to check it out before you give up on your idea
(which to my of thinking sounds postively delightful!)
Hope this helps...
Susan
Expressions Pottery Workshop
East Granby, CT
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