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removing slips from greenware design features

updated sun 13 oct 02


Martin Howard on wed 9 oct 02

A similar problem to the one of removing colorant from bisque
is that of how to remove unwanted slip from the area of greenware
surrounding impressed detailed, such as letters.

I have spent many hours scraping (with mask on!) dry slip with a potters
knife around impressed lettering. It is never really successful.

Have you other ideas? I make cat bowls in red earthenware fired at cone 1-3;
I impress the name at leather hard with lead printers letters; slip trail or
dip in slip and when leather hard again, scrape away ... and away ...

Martin Howard
Webbs Cottage Pottery
Woolpits Road, Great Saling
01371 850 423
Updated 6th July 2002

Roger Graham on thu 10 oct 02

For Martin Howard, asking about removing excess slip from around impressed
designs on greenware. I also became disenchanted with slow fiddly scraping
with a knife blade. Found a better way. Let the pot dry completely, and rub
it back with steel wool.

Works so well! But I didn't like the little fragments of steel wool
escaping, so tried the same method using a stiff nylon (?) pot scouring pad.
Sold in the kitchen department of a hardware store, these things look rather
like a post-card sized piece of towelling, but made of stiff plastic fibrous
stuff. Works just as well as steel wool, but without the escaping fragments.

Don't all jump on me and yell about clay dust. I know, I know. Find a way to
do it safely, without scattering the dust about.

Roger Graham, near Gerringong, Australia.

Bobbruch1@AOL.COM on fri 11 oct 02

After drawing your designs with a sharp edged tool, you could try carving the
designs into the clay. If you use a glaze which changes considerably where
it pools, the glaze will tend to pool in the carved areas. Korean celadons of
over 600 years ago would provide excellent examples of that method.

If significant color differentiation is important, you could paint your
colorant into the carved areas and scrape away any excess colorant from the
surface of the pot while it is still green. You may need to do some sanding
after the bisque, which is one disadvantage of that method. The other is that
it will be difficult to get the loose feeling that would result from the wax
resist method or by just painting the design directly on the pots. It also is
a little more labor intensive than the other methods and may not yield a
satisfactory economic return if that is a goal. If economic viability isn't
at all relevant, you could consider filling some/all of the carved areas with
colored clay (has to have the same shrinkage and dryness as the clay used in
the pot to avoid cracking) and scrapping it away to achieve an even surface,
i.e., Mishima (SP) ware, another early Korean method. The scraping will
produce "some" of the loose feeling that you would obtain from a brush. A
local museum might have examples of these Korean and similar Japanese pots,
or you should be able to find them in books.

Hope this helps,

Bob Bruch

Elizabeth Hunt on fri 11 oct 02


I used to do quite a bit of mishima, or slip-inlaid
incised designs, and like Roger Graham, "sanded" the
excess slip away from the bone dry pot with steel wool
or scouring pads. As one who HATES wearing masks while
I work (yes, shame on me!), I tried something that
worked well and produced a great deal less dust.

After the pot and slip become bone dry, I take a bowl
of water and a sponge and wet-wipe about 99% of the
excess slip off, rinsing out the sponge frequently. If
you are using a darker clay body than the inlaid slip,
the clay colour will smear onto the slip design, but
it's just a thin residue that will come off easily
with a very light buffing with the steel wool or
scouring pad.....and voila...much less dust and clean,
crisp inlay. Also, I found that the wet sponge also
takes a lot less elbow grease than solely rubbing with
steel wool.

Hope this helps.
Elizabeth Hunt
in rural Eastern Shore of Virginia where much needed
rain is hatching more mosquitos and making for slow
drying pots...but then again, everything is slow here
on the Eastern Shore

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