Jeanie Campbell on mon 23 jun 03
I went with a friend to a "ceramist show" which is primarily molded
ceramics, china painting, dolls, etc. One of the exhibitors had a molding
material that is flexible after it sets, yet holds details. BUT, it was
very pricy. ($22 for about a pint--Yeow!)
Has anyone used anything similar but cheaper, or are we best off using
plaster?
Jeanie
John Rodgers on tue 24 jun 03
Jeanie, you post was not very clear to me. I work a lot with molds and
"molded ceramics". That is plaster molds into which one slipcasts clay
slip - to get the form. I'm not sure what you were looking at. What were
the molded ceramics. Were they actually a ceramics material, molded
(slipcast) fired to bisque, china painted and fired again? In which case
they become inflexible, or were they of some other material that can be
molded, painted and not fired, to maintain the flexibility? I can't
imagine any material retaining flexibility and color through a kiln
firing. Would like to know about this if that is the way it really works.
There are flexible mold materials that are used for making plaster
casts, which are often painted, but plaster casts are never fired. They
would blow apart, and they are rigid when the plaster sets.
Would appreciate more information please.
Thanks,
John Rodgers
Birmingham, AL
Jeanie Campbell wrote:
>I went with a friend to a "ceramist show" which is primarily molded
>ceramics, china painting, dolls, etc. One of the exhibitors had a molding
>material that is flexible after it sets, yet holds details. BUT, it was
>very pricy. ($22 for about a pint--Yeow!)
>
>Has anyone used anything similar but cheaper, or are we best off using
>plaster?
>
>Jeanie
>
>______________________________________________________________________________
>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.
>
>
>
Longtin, Jeff on tue 24 jun 03
Jeanie,
The product you're referring to is probably a polyurethane rubber. That
sounds a tad expensive but, for the most part, the stuff is not cheap.
It is a very useful product if you're molding a complex, and delicate(?)
form. If you're just molding a pot, or some other basic round shape, plaster
should do the trick.
Generally I use urethane when a sculptor brings me a delicate scuplture,
i.e. made with oil base clay, with thin appendages, etc., and I need to
reproduce the form in plaster before I try casting a mold. It greatly
increases the cost but if the original is a "once-in-a-lifetime" creation,
or otherwise took a long time to create, than it is the safest way to go.
Good luck
Jeff Longtin
-----Original Message-----
From: Jeanie Campbell [mailto:seanjeanie@MSN.COM]
Sent: Monday, June 23, 2003 8:02 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Molding material?
I went with a friend to a "ceramist show" which is primarily molded
ceramics, china painting, dolls, etc. One of the exhibitors had a molding
material that is flexible after it sets, yet holds details. BUT, it was
very pricy. ($22 for about a pint--Yeow!)
Has anyone used anything similar but cheaper, or are we best off using
plaster?
Jeanie
____________________________________________________________________________
__
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.
Jeanie Campbell on tue 24 jun 03
Thanks, Jeff. That's helpful. I've made a large area tile backsplash fo=
r a sink counter, and it has a relief design. I'd like to be able to rep=
roduce it without all the work. Each tile is about 9.5x9.5 and each uniq=
ue. I'm looking for something easier than plaster, and perhaps taking le=
ss storage space.
Jeanie
----- Original Message -----
From: Longtin, Jeff
Sent: Tuesday, June 24, 2003 8:26 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Molding material?
Jeanie,
The product you're referring to is probably a polyurethane rubber. That
sounds a tad expensive but, for the most part, the stuff is not cheap.
It is a very useful product if you're molding a complex, and delicate(?)
form. If you're just molding a pot, or some other basic round shape, plas=
ter
should do the trick.
Generally I use urethane when a sculptor brings me a delicate scuplture,
i.e. made with oil base clay, with thin appendages, etc., and I need to
reproduce the form in plaster before I try casting a mold. It greatly
increases the cost but if the original is a "once-in-a-lifetime" creation=
,
or otherwise took a long time to create, than it is the safest way to go.
Good luck
Jeff Longtin
-----Original Message-----
From: Jeanie Campbell [mailto:seanjeanie@MSN.COM]
Sent: Monday, June 23, 2003 8:02 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Molding material?
I went with a friend to a "ceramist show" which is primarily molded
ceramics, china painting, dolls, etc. One of the exhibitors had a moldin=
g
material that is flexible after it sets, yet holds details. BUT, it was
very pricy. ($22 for about a pint--Yeow!)
Has anyone used anything similar but cheaper, or are we best off using
plaster?
Jeanie
_________________________________________________________________________=
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melpots@pclink.com.
_________________________________________________________________________=
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Snail Scott on tue 24 jun 03
At 06:02 PM 6/23/03 -0700, you wrote:
>...molded
>ceramics...One of the exhibitors had a molding
>material that is flexible after it sets, yet holds details...
Was this an absorbent material, then, if it was used for
slip-casting? I've never heard of a flexible yet absorbent
mold material.
Many folks are beginning to use 'rubber' (latex, silicone or
urethane) molds for clay, but it work best for press-molding,
where absorbency is not required. (Nan Smith is one of the
noted users of that techique.) It's terrific stuff, but none
of the varieties is cheap. My favorite, a urethane, runs
$95 for a two-gallon batch, not counting shipping.
Even if it were possible to cast slip in a flexible mold,
though, it needs to be remembered that the absorbency of
plaster isn't just a surface effect. It requires an optimum
thickness of plaster not just to provide strength to the
mold, but to provide a volume of absorbent material to draw
out the water from the slip. Any flexible mold material
would still require such a volume, unless it were much more
absorbent than plaster, and a mold made of flexible material
would become much more inflexible if it were as thick as a
plaster mold! Many 'rubber' molds use a plaster backing to
provide rigidity, but even if the rubber were absorbent, I
suspect that it could not transfer moisture evenly across
the discontinuity into the plaster jacket.
Slip-casting requires an absorbent mold; thus the standard
use of plaster. If someone is actually slip-casting with a
flexible mold material, I'd be very curious to find out
more.
-Snail
Jeanie Campbell on tue 24 jun 03
Hi, John,
Sorry that I'm not more clear. Sr. moments occur often. =20
The vendor was selling a two-part substance to be blended into one substa=
nce, and used for a flexible mold. There were a lot of porcelain doll ma=
kers there, and my assumption was that the mold plastics (silicones?) wer=
e making small molds for parts of dolls. Or jewelry. The examples of mo=
lds were fairly small. They kept great details of the object molded, and=
did not take up the bulk to store like plaster molds do. What people wo=
uld put into the mold would be porcelain clay (for dolls) or whatever the=
y made their jewelry from (plastics, or porcelain?). =20
To be more clear: What I have made is about 40 9.5"x9.5" relief tiles fo=
r a backsplash. I would like to be able to mold each tile (no repeat des=
igns) and duplicate the backsplash without all the work. If there is a f=
lexible mold that is easy and stores well with less bulk than plaster, I'=
d like to experiment with it. =20
I thought someone probably has already has experience with silicone or ru=
bber molds and could steer me in the right direction, so I don't have to =
do all that work. Not lazy! -- I prefer to think of myself as "efficient=
."
Thanks. Jeanie
----- Original Message -----
From: John Rodgers
Sent: Tuesday, June 24, 2003 8:14 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Molding material?
Jeanie, you post was not very clear to me. I work a lot with molds and
"molded ceramics". That is plaster molds into which one slipcasts clay
slip - to get the form. I'm not sure what you were looking at. What were
the molded ceramics. Were they actually a ceramics material, molded
(slipcast) fired to bisque, china painted and fired again? In which case
they become inflexible, or were they of some other material that can be
molded, painted and not fired, to maintain the flexibility? I can't
imagine any material retaining flexibility and color through a kiln
firing. Would like to know about this if that is the way it really works.
There are flexible mold materials that are used for making plaster
casts, which are often painted, but plaster casts are never fired. They
would blow apart, and they are rigid when the plaster sets.
Would appreciate more information please.
Thanks,
John Rodgers
Birmingham, AL
Jeanie Campbell wrote:
>I went with a friend to a "ceramist show" which is primarily molded
>ceramics, china painting, dolls, etc. One of the exhibitors had a moldi=
ng
>material that is flexible after it sets, yet holds details. BUT, it was
>very pricy. ($22 for about a pint--Yeow!)
>
>Has anyone used anything similar but cheaper, or are we best off using
>plaster?
>
>Jeanie
>
>________________________________________________________________________=
______
>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@pcli=
nk.com.
>
>
>
_________________________________________________________________________=
_____
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/
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r.msn.com
Ababi on tue 24 jun 03
If this is the same polyurethane that being used for isolation; Be aware. when contact
with fire releases cyanide!
ababi
---------- Original Message ----------
>Jeanie,
>The product you're referring to is probably a polyurethane rubber.
Longtin, Jeff on tue 24 jun 03
Jeanie,
A thought: I've tended to use the urethane when molding something like
you've described. It does come in a brushable format so you don't have to
buy alot, but it does take awhile to build up a durable layer. (You would
then "mother mold" the subsequent rubber layer with plaster.)
Not too long ago I spoke with someone who liked to use silicone chaulking
instead of the commercial stuff. It is roughly the same substance so that's
not an issue but the workability is a little different. He explained that he
applies liquid soap to his fingers and then manually applies the rubber to
his pieces. I see no reason why you couldn't experiment with it yourself. (I
would suggest you wear gloves of some sort however.) If you've never used
the stuff be prepared for one hell of an odor though!
Regardless of which type of rubber you use a mother mold is probably
necessary. You might also try Friendly Plastic, or a similar material, as a
mother mold. (A mother mold is simply a "backing" mold to support the flimsy
thin rubber.)
Plaster is really cheap and easy to use, rubber is relatively expensive and
a bit more difficult but much more convenient in the long run.
take care
Jeff Longtin
Complex Molds Made Easy
minneapolis
-----Original Message-----
From: Jeanie Campbell [mailto:seanjeanie@MSN.COM]
Sent: Tuesday, June 24, 2003 11:15 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Molding material?
Thanks, Jeff. That's helpful. I've made a large area tile backsplash for a
sink counter, and it has a relief design. I'd like to be able to reproduce
it without all the work. Each tile is about 9.5x9.5 and each unique. I'm
looking for something easier than plaster, and perhaps taking less storage
space.
Jeanie
----- Original Message -----
From: Longtin, Jeff
Sent: Tuesday, June 24, 2003 8:26 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Molding material?
Jeanie,
The product you're referring to is probably a polyurethane rubber. That
sounds a tad expensive but, for the most part, the stuff is not cheap.
It is a very useful product if you're molding a complex, and delicate(?)
form. If you're just molding a pot, or some other basic round shape, plaster
should do the trick.
Generally I use urethane when a sculptor brings me a delicate scuplture,
i.e. made with oil base clay, with thin appendages, etc., and I need to
reproduce the form in plaster before I try casting a mold. It greatly
increases the cost but if the original is a "once-in-a-lifetime" creation,
or otherwise took a long time to create, than it is the safest way to go.
Good luck
Jeff Longtin
-----Original Message-----
From: Jeanie Campbell [mailto:seanjeanie@MSN.COM]
Sent: Monday, June 23, 2003 8:02 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Molding material?
I went with a friend to a "ceramist show" which is primarily molded
ceramics, china painting, dolls, etc. One of the exhibitors had a molding
material that is flexible after it sets, yet holds details. BUT, it was
very pricy. ($22 for about a pint--Yeow!)
Has anyone used anything similar but cheaper, or are we best off using
plaster?
Jeanie
____________________________________________________________________________
__
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.
____________________________________________________________________________
__
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.Get more from the Web. FREE MSN Explorer download :
http://explorer.msn.com
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
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Moderator of the list is Mel Jacobson who may be reached at
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Rick Monteverde on tue 24 jun 03
I've experimented with thin latex skin molds with a plaster back with (very)=
limited success. I suspect an even better choice would be a foam latex=
(needs an autoclave) or flexible foam urethane (no autoclave needed with=
most versions), both of which form only a thin skin that would preserve=
detail while offering a minimal barrier to water transfer. The thicker=
sponge backing would mitigate the problem of an uneven contact to the=
absorbent bulk plaster backing which you mentioned.=20
- Rick
Snail Scott on tue 24 jun 03
At 09:26 AM 6/24/03 -0700, you wrote:
> What I have made is about 40 9.5"x9.5" relief tiles for a backsplash. I
would like to be able to mold each tile (no repeat designs) and duplicate
the backsplash without all the work. If there is a flexible mold that is
easy and stores well with less bulk than plaster, I'd like to experiment
with it.
A flexible 'rubber' mold would work fairly well for
press-molding tiles. It won't save a lot of bulk,
but it will save a little, and weight a lot less.
Typically, the rubber is a thin (1/8" or so) layer
with a rigid backer, usually plaster or fiberglass.
I prefer plaster myself - less nasty to work with.
It's not like a plaster mold, though - not thick
and heavy. Typically such backers are reinforced
with fiber, though as I tell my mold-making students,
that's a bit of a misnomer. In terms of relative
volume, it's not really fiber-reinforced plaster,
but plaster-reinforced fiber: more fiber than plaster;
lightweight and thin, lots of strength.
The rubber (of whichever sort) is expensive, but on
a simple flat object like tile, it'll go a long way.
Don't just get whatever these folks are flogging;
there are a lot of companies that make mold rubbers
of various types...investigate! Two major makers are
Polytek (which I know Jeff likes) and Smooth-on
(which I use). They're both good - ask for the
literature and read up - different formulations are
optimized for different applications. For press-
molding shapes with few undercuts, I would go with
a Shore 60 hardness, so that the detail won't distort
when you press the clay in. Softer rubbers are good
for undercuts, but work better with poured media
(like plastics or wax) where distortion from pressure
is not a issue. I would also suggest a pourable
rubber rather than a brushable one - quicker to
make the mold, usually.
Honestly, though, I don't think you'll save much
space this way, and it will cost a fair amount of
money compared with plaster. You will save weight,
but you will also require more time and labor
compared with a plaster mold. If you decide to go
with the rubber mold option, I'll try to advise, but
I'm not sure I'd go that route myself.
-Snail
Snail Scott on tue 24 jun 03
At 03:16 PM 6/24/03 -0500, you wrote:
>Not too long ago I spoke with someone who liked to use silicone chaulking
>instead of the commercial stuff....he
>applies liquid soap to his fingers and then manually applies the rubber to
>his pieces.(I
>would suggest you wear gloves of some sort however.)...
This method does work, though I'm not sure it's enough
cheaper. Not only are the fumes intense and TOXIC, but
skin contact with silicone caulk is also quite toxic.
A little on your fingers won't kill you, but by the time
you smear forty 10" tiles by hand, you're talking a lot
of exposure, even if the fumes haven't driven you out
of the studio. If you do try this method, wear gloves,
use a brush to apply the contact coat and putty knife to
thicken it up, and LOTS of fresh air!!! You can really
make yourself sick from silicone caulk fumes.
-Snail
Snail Scott on tue 24 jun 03
At 08:37 PM 6/24/03 +0200, you wrote:
>If this is the same polyurethane that being used for isolation; Be aware.
when contact
>with fire releases cyanide!
I think you're thinking of the polycyanurate insulation
foam; urethane rubber mold material is different.
-Snail
John Rodgers on tue 24 jun 03
Jeanie, PolyTek Corporation makes a two-part brushable rubber compound
that is easy to work with. Apply mold release to the surface of your
model, mixt equal parts of the brushable rubber in a bowl, and brush it
onto the model. Once cured, make a "mothor" or support mold for the
rubber. Make it from plaster, moldable plastics, or use twopart
plumbers epoxy. I use this last stuff a lot. Works for me.
Regards,
John Rodgers
Birmingham, AL
Jeanie Campbell wrote:
>I went with a friend to a "ceramist show" which is primarily molded
>ceramics, china painting, dolls, etc. One of the exhibitors had a molding
>material that is flexible after it sets, yet holds details. BUT, it was
>very pricy. ($22 for about a pint--Yeow!)
>
>Has anyone used anything similar but cheaper, or are we best off using
>plaster?
>
>Jeanie
>
>______________________________________________________________________________
>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.
>
>
>
Ababi on wed 25 jun 03
You might be right, however here it is called polyurethane.
By the way I helped A scared potter to relax: She was afraid when I gave her a recipe
with Nepheline "Cyanide".
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
---------- Original Message ----------
>At 08:37 PM 6/24/03 +0200, you wrote:
>>If this is the same that being used for isolation; Be aware.
>when contact
>>with fire releases cyanide!
>I think you're thinking of the polycyanurate insulation
>foam; urethane rubber mold material is different.
> -Snail
>______________________________________________________________________________
>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.
Snail Scott on wed 25 jun 03
At 08:18 PM 6/25/03 -0400, you wrote:
>...I use
>urethane as a press mold (with a plaster mother mold), but i loose a
>lot of surface detail this way...
What urethane are you using? Most makers of rubber molds
use a Shore 40 rubber for flexibility, which is nice
when working with poured media like wax or resin, but
isn't intended to resist pressure. For a press-mold, you
need something that won't distort. Try a rubber with at
least a Shore 60 hardness. You should be able to find
one in either a brushable or pourable formulation -
whichever you prefer.
-Snail
Robert Huskey on wed 25 jun 03
Jeanie, I think that I would use a plaster mold ( 40 plaster molds) .
After letting the clay sit in the plaster mold for a few hours, you
can just dump it out. On the other hand, in the rubber or silicone mold the
clay will only dry on the exposed surface. When you pry
the tile out, it will distort and not want to fire flat. Actually, if the
rubber mold doesn't form the sides of the tile; in other words, if
you roll the mold into the slab or the slab onto the mold, and cut the tile
to size afterwards.
Bob Huskey -- Tallahassee, Florida
----- Original Message -----
From: "Jeanie Campbell"
To:
Sent: Tuesday, June 24, 2003 12:26 PM
Subject: Re: Molding material?
Hi, John,
Sorry that I'm not more clear. Sr. moments occur often.
The vendor was selling a two-part substance to be blended into one
substance, and used for a flexible mold. There were a lot of porcelain doll
makers there, and my assumption was that the mold plastics (silicones?) were
making small molds for parts of dolls. Or jewelry. The examples of molds
were fairly small. They kept great details of the object molded, and did
not take up the bulk to store like plaster molds do. What people would put
into the mold would be porcelain clay (for dolls) or whatever they made
their jewelry from (plastics, or porcelain?).
To be more clear: What I have made is about 40 9.5"x9.5" relief tiles for a
backsplash. I would like to be able to mold each tile (no repeat designs)
and duplicate the backsplash without all the work. If there is a flexible
mold that is easy and stores well with less bulk than plaster, I'd like to
experiment with it.
lisa on wed 25 jun 03
On Tuesday, June 24, 2003, at 12:28 PM, Snail Scott wrote:
> If someone is actually slip-casting with a
> flexible mold material, I'd be very curious to find out
> more.
>
> -Snail
>
Yeah, I'd really like to know if this can be done myself. I use
urethane as a press mold (with a plaster mother mold), but i loose a
lot of surface detail this way and have to re-work my pieces after
removing them from the mold. Also, I have to press clay into the open
mold, let it harden to leather-hard, then join the pieces, rather than
just pouring slip into a closed mold.
I do have an acquaintance that uses poured urethane (instead of
painted-on) to make tile molds. He puts the original tile in the bottom
of a little made-to-fit box (his tiles are usually no more than 2"x2")
and pours the urethane in on top, like you would with plaster. He makes
a little block about an inch thick, which gives him enough stiffness to
use the mold as a press mold. Absorbency is not an issue since the
pressed tiles are open to the air and thin enough to stiffen up
sufficiently to be removed from the mold. I guess with large tiles
there would be warping, but worth a try.
Lisa
> _______________________________________________________________________
> _______
> 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/
>
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>
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