Ellen Currans on sun 28 nov 04
Dear Kate,
Two thirds of my production is slab work using molds. I have only two
plaster molds I made myself - heavy, hard to turn, take up a lot of room in storage.
Since I moved to slab work to take the strain off arthritic joints, etc, it
doesn't make sense to handle a lot of heavy plaster molds. The molds I use
are old (metal, glass, ceramic,wood) trays, platters, bowls, etc. bought cheap
at Goodwill or paid dearly for at fine Kitchen stores. Most of them are
absolutely plain - just forms to hold the clay which has impressed designs or foam
rubber stamped on-glaze decoration. They are square, rectangular, oval,
oblong, round and range from 6 inches square to
32 inches long.
If you make your own plaster molds you will probably start with a purchased
or ready made form, so the idea that it is not very creative to use old forms
directly doesn't apply here. The 18th C. shapes you want are pretty standard
and pretty universal. Just backgrounds for your slip work.
The same restrictions on plaster molds (no sharp corners or reverse angles)
apply to glass, wood, metal or ceramic. There are a great many wonderful old
discarded tray shapes and other forms out there. Some work better than
others but you have to figure that out by trying them. (I find that too flat
shapes don't work, or those with too vertical rims, or anything too fussy, cutesy,
etc.)
The trick is to spread a fine coat of WD-40 over the form before you lay the
clay on it. It must be completely covered (clay will stick to dry spots). You
can try this for the first time with a small spray bottle of WD-40 but I
prefer to buy it by the gallon and use a foam brush so there isn't spray in the
air. One of the advantages of this method is that if your piece has a texture
or design on it, you can slide it around on the form to get it placed right.
It won't slide on plaster. I trim against the rim with a wire cheese cutter,
but if you like something more uneven you can cut it anyway you want. You can
often use either the top or bottom of the form for two different effects.
Lay a newspaper over them and leave them to firm enough to handle without
distortion. Turn out and finish the back edges, and go on with your decoration.
In your case, perhaps the decoration (slip trailing) went on before the clay
went on the form or just after it was made. I dry mine in a plastic covered
shelving unit, slowly, and use all the usual tricks of handling to avoid
warping.
Try this with a simple old pyrex pie pan to see how it works.
Ellen Currans
In Dundee, Oregon
Where I had to build special shelving behind the slab roller to hold over 500
recycled old platters, plates, oblong plastic bowls, etc. I can't imagine
where I would store that many plaster molds!
Kate Johnson on mon 29 nov 04
> Dear Kate,
>
> Two thirds of my production is slab work using molds. I have only two
> plaster molds I made myself - heavy, hard to turn, take up a lot of room
> in storage.
> Since I moved to slab work to take the strain off arthritic joints, etc,
> it
> doesn't make sense to handle a lot of heavy plaster molds.
Hi Ellen! You make good points here--part of the reason I've gone to
handbuilding is the arthritis in hands and right shoulder, never thought
about the _weight_ of plaster molds...though I would still like to make a
matched set to construct some of my smallish flasks...
The molds I use
> are old (metal, glass, ceramic,wood) trays, platters, bowls, etc. bought
> cheap
> at Goodwill or paid dearly for at fine Kitchen stores. Most of them are
> absolutely plain - just forms to hold the clay which has impressed designs
> or foam
> rubber stamped on-glaze decoration. They are square, rectangular, oval,
> oblong, round and range from 6 inches square to 32 inches long.
Ta DAH, me too, at present! I have pie plates, baking pans,
bowls,casseroles, and one platter that I've used just that way, and OH yeah
thrift stores are dandy places for this. I thoroughly dislike Melamine, but
I found a matched pair of small bowls that work great for my small flasks!
I have a small Pyrex individual casserole that works wonderfully for one
half of a press-mold flask, but I really need two--otherwise there's the
possibility of uneven drying between the sides.
Must. Go. Thrifting...
>
> If you make your own plaster molds you will probably start with a
> purchased
> or ready made form, so the idea that it is not very creative to use old
> forms
> directly doesn't apply here. The 18th C. shapes you want are pretty
> standard
> and pretty universal. Just backgrounds for your slip work.
Yep, they are VERY basic. What I'm wanting at the moment is something like
the wonderful rounded rectangular servers...I tried something similar by
draping near-leather-hard clay over the back of a Pyrex loaf pan, and it
looks lovely, but not quite there...
Some of my stuff is simpler still, just redware with transparent glaze, as
you can see here--
http://pg.photos.yahoo.com/ph/graphicartepsi/album?.dir=/4870 . There are a
couple of Revolutionary War era bakers I'm hoping to make following that
idea, too...so the shape is everything in that case.
>
> The same restrictions on plaster molds (no sharp corners or reverse
> angles)
> apply to glass, wood, metal or ceramic. There are a great many wonderful
> old
> discarded tray shapes and other forms out there. Some work better than
> others but you have to figure that out by trying them. (I find that too
> flat
> shapes don't work, or those with too vertical rims, or anything too fussy,
> cutesy,
> etc.)
You're getting me inspired to Shop, and I HATE shopping!
>
> The trick is to spread a fine coat of WD-40 over the form before you lay
> the
> clay on it. It must be completely covered (clay will stick to dry spots).
> You
> can try this for the first time with a small spray bottle of WD-40 but I
> prefer to buy it by the gallon and use a foam brush so there isn't spray
> in the
> air.
Whoa, now THAT is an idea that hadn't occurred to me! REALLY. I wonder if
Armor-All would work, too? It's considerably less stinky. I would worry
about these products making your glaze adhere unevenly--you don't have any
problems with that?
What I use, when I'm not doing a demo at an historic site, that is, is a
very thin, slimpsy layer of a plastic trash bag cut to shape. That
separates the clay from the mold and keeps that wet-clay-suction thing from
happening (learned about THAT the hard way!). I do sometimes have to
deal with the problem of wrinkle marks though. If my clay's not too
groggy, it's not a big deal...wet sponge or metal rib fixes it.
I trim against the rim with a wire cheese cutter,
> but if you like something more uneven you can cut it anyway you want. You
> can
> often use either the top or bottom of the form for two different effects.
I have a wooden box I use both ways, inside and out.
>
> Lay a newspaper over them and leave them to firm enough to handle without
> distortion. Turn out and finish the back edges, and go on with your
> decoration.
> In your case, perhaps the decoration (slip trailing) went on before the
> clay
> went on the form or just after it was made. I dry mine in a plastic
> covered
> shelving unit, slowly, and use all the usual tricks of handling to avoid
> warping.
>
> Try this with a simple old pyrex pie pan to see how it works.
Have done, but now I'm all interested to try your WD-40 idea...many thanks!
God I love new ideas...
Best--
Kate
Marcia Selsor on mon 29 nov 04
You can lighten up molds by using styrofoam cores and coating with
plaster.
Another possibiity is to hold a balloon or ball in the inverted mold
until the plaster solidifies. This really helps lighten up sink molds a
la Linda Blossom. I use draped canvas tied over a garbage can and pour
the plaster into that. It is solid but not a deep form.
For deep dish molds I shape styrofoam and coat with plaster. I also use
wood sandwiches for extended lips off the molds.
Marcia Selsor in COLD Montana
On Nov 29, 2004, at 7:51 AM, Kate Johnson wrote:
>> Dear Kate,
>>
>> Two thirds of my production is slab work using molds. I have only two
>> plaster molds I made myself - heavy, hard to turn, take up a lot of
>> room
>> in storage.
>> Since I moved to slab work to take the strain off arthritic joints,
>> etc,
>> it
>> doesn't make sense to handle a lot of heavy plaster molds.
>
> Hi Ellen! You make good points here--part of the reason I've gone to
> handbuilding is the arthritis in hands and right shoulder, never
> thought
> about the _weight_ of plaster molds...though I would still like to
> make a
> matched set to construct some of my smallish flasks...
>
> The molds I use
>> are old (metal, glass, ceramic,wood) trays, platters, bowls, etc.
>> bought
>> cheap
>> at Goodwill or paid dearly for at fine Kitchen stores. Most of them
>> are
>> absolutely plain - just forms to hold the clay which has impressed
>> designs
>> or foam
>> rubber stamped on-glaze decoration. They are square, rectangular,
>> oval,
>> oblong, round and range from 6 inches square to 32 inches long.
>
> Ta DAH, me too, at present! I have pie plates, baking pans,
> bowls,casseroles, and one platter that I've used just that way, and OH
> yeah
> thrift stores are dandy places for this. I thoroughly dislike
> Melamine, but
> I found a matched pair of small bowls that work great for my small
> flasks!
> I have a small Pyrex individual casserole that works wonderfully for
> one
> half of a press-mold flask, but I really need two--otherwise there's
> the
> possibility of uneven drying between the sides.
>
> Must. Go. Thrifting...
>>
>> If you make your own plaster molds you will probably start with a
>> purchased
>> or ready made form, so the idea that it is not very creative to use
>> old
>> forms
>> directly doesn't apply here. The 18th C. shapes you want are pretty
>> standard
>> and pretty universal. Just backgrounds for your slip work.
>
> Yep, they are VERY basic. What I'm wanting at the moment is something
> like
> the wonderful rounded rectangular servers...I tried something similar
> by
> draping near-leather-hard clay over the back of a Pyrex loaf pan, and
> it
> looks lovely, but not quite there...
>
> Some of my stuff is simpler still, just redware with transparent
> glaze, as
> you can see here--
> http://pg.photos.yahoo.com/ph/graphicartepsi/album?.dir=/4870 . There
> are a
> couple of Revolutionary War era bakers I'm hoping to make following
> that
> idea, too...so the shape is everything in that case.
>>
>> The same restrictions on plaster molds (no sharp corners or reverse
>> angles)
>> apply to glass, wood, metal or ceramic. There are a great many
>> wonderful
>> old
>> discarded tray shapes and other forms out there. Some work better
>> than
>> others but you have to figure that out by trying them. (I find that
>> too
>> flat
>> shapes don't work, or those with too vertical rims, or anything too
>> fussy,
>> cutesy,
>> etc.)
>
> You're getting me inspired to Shop, and I HATE shopping!
>>
>> The trick is to spread a fine coat of WD-40 over the form before you
>> lay
>> the
>> clay on it. It must be completely covered (clay will stick to dry
>> spots).
>> You
>> can try this for the first time with a small spray bottle of WD-40
>> but I
>> prefer to buy it by the gallon and use a foam brush so there isn't
>> spray
>> in the
>> air.
>
> Whoa, now THAT is an idea that hadn't occurred to me! REALLY. I
> wonder if
> Armor-All would work, too? It's considerably less stinky. I would
> worry
> about these products making your glaze adhere unevenly--you don't have
> any
> problems with that?
>
> What I use, when I'm not doing a demo at an historic site, that is, is
> a
> very thin, slimpsy layer of a plastic trash bag cut to shape. That
> separates the clay from the mold and keeps that wet-clay-suction thing
> from
> happening (learned about THAT the hard way!). I do sometimes have
> to
> deal with the problem of wrinkle marks though. If my clay's not too
> groggy, it's not a big deal...wet sponge or metal rib fixes it.
>
> I trim against the rim with a wire cheese cutter,
>> but if you like something more uneven you can cut it anyway you want.
>> You
>> can
>> often use either the top or bottom of the form for two different
>> effects.
>
> I have a wooden box I use both ways, inside and out.
>>
>> Lay a newspaper over them and leave them to firm enough to handle
>> without
>> distortion. Turn out and finish the back edges, and go on with your
>> decoration.
>> In your case, perhaps the decoration (slip trailing) went on before
>> the
>> clay
>> went on the form or just after it was made. I dry mine in a plastic
>> covered
>> shelving unit, slowly, and use all the usual tricks of handling to
>> avoid
>> warping.
>>
>> Try this with a simple old pyrex pie pan to see how it works.
>
> Have done, but now I'm all interested to try your WD-40 idea...many
> thanks!
> God I love new ideas...
>
> Best--
> Kate
>
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>
bonnie staffel on tue 30 nov 04
Dear Kate,
When I was recovering from CTS surgery a friend gave me his Styrofoam slump
molds. They worked nicely, but when I was able to work more, I had thrown
bowls and half shapes, even shapes to make lids for my casseroles, where I
could drape the clay slab into or over. When using a bisque bowl, you have
the added advantage of the bisque absorbing moisture so that it releases
right away. To place a slab into a bowl form, cut the slab into a rounded
butterfly 2 wing shape with the cutting of the wings down to approximately
the diameter of the bottom of the bowl. The wings overlap which can be
pressed into one piece. Or you can cut away the excess and slip them
together. You could make your own bisque forms if you don't want to throw
them by using a Styrofoam ball, mold clay over half and duplicate it so you
have two forms. I have used other non-absorptive molds and was frustrated
with waiting for them to dry enough to release. I have made very large
molds (or you could ask another potter to do this for you) or you can use
flower pots for molds. Your imagination has no bounds with this method.
Love it!
You can see examples of this process on the Pottery Gallery page of my web
site, there are two pots second row center and one pot second from the left
on the bottom row. The top two were smoke fired and the bottom one was
porcelain with Barnard Slip inlay fired to Cone 9.
http://webpages.charter.net/bstaffel/potterygallery12.htm
With the bisque mold, you can take it out the pressed form almost
immediately and make a second one to attach to the bottom bowl to make a
round form. The first pot in the upper row was applied with pressed
wads/coils rather than slabs. One gets a whole new pattern to the form, but
while making the porcelain pot I added thin slices of the slipped clay. I
introduced this technique when teaching in Denmark.
The process of throwing is my first love, but I am also drawn to the press
mold forms for a fresh look and new adventures in firing techniques.
Warm regards,
Bonnie Staffel
http://webpages,charter.net/bstaffel
http://vasefinder.com/bstaffelgallery1.html
Potters Council Charter member
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