Julie Milazzo on thu 30 may 02
Hmmm... what about vaseline? I know that it works for
plaster molds of faces... Jules
--- Marianne Lombardo wrote:
> I have two small 3" relief carved disks that I wish
> to pour plaster over to make a negative impression.
> They look like they are made of some sort of very
> hard plaster and rubbed with a painted finish.
>
> My question is, do I need to put anything on them to
> prevent the pottery plaster from sticking forever?
> This is the first time I've tried this and I would
> prefer not to ruin the original pieces.
>
> I thought of dusting with talc first but some of the
> carving is very detailed and the talc might clog it
> up.
>
> Thank-you in advance.
>
> Marianne Lombardo
> Omemee, Ontario, Canada
>
>
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Marianne Lombardo on thu 30 may 02
I have two small 3" relief carved disks that I wish to pour plaster over =
to make a negative impression. They look like they are made of some =
sort of very hard plaster and rubbed with a painted finish.
My question is, do I need to put anything on them to prevent the pottery =
plaster from sticking forever? This is the first time I've tried this =
and I would prefer not to ruin the original pieces.
I thought of dusting with talc first but some of the carving is very =
detailed and the talc might clog it up.
Thank-you in advance.
Marianne Lombardo
Omemee, Ontario, Canada
john hooker on fri 31 may 02
--- Marianne Lombardo wrote:
> Thanks to all that responded to my question about
> plaster molds sticking to
> pottery plaster.
>
> I've been experimenting with it for about 5 hours so
> far. I tried vaseline,
> cooking spray, and butter. I'm almost there. But
> some of the very small
> detail is breaking off when I take the original form
> out of the plaster.
>
> Is it because I am not waiting long enough for the
> plaster to dry? Someone
> had told me to wait only 20 minutes to half hour.
> The plaster is very soft.
>
> At least I've been able to clean it off of the
> original form okay.
>
> Marianne Lombardo
>
> Marianne, 20 minutes is not long enough, when you
first pour your mould the plaster is slightly warm, it
slwly gets hotter and then slowly gets colder. When it
is cold you open it, if you open it to soon it has not
set and is week. Liquid soap is the best releasig
agent. Cheers
Hook________________________________________________________________________
______
> 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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> reached at melpots@pclink.com.
__________________________________________________
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Brian Crocker on fri 31 may 02
Only ever use Soap as a release agent never "any" petroleum based materials.
Regards CROC.
========================
----- Original Message -----
From: "Julie Milazzo"
To:
Sent: Friday, May 31, 2002 12:41 PM
Subject: Re: Plaster Mold Question Re Sticking
> Hmmm... what about vaseline? I know that it works for
> plaster molds of faces... Jules
>
>
> --- Marianne Lombardo wrote:
> > I have two small 3" relief carved disks that I wish
> > to pour plaster over to make a negative impression.
> > They look like they are made of some sort of very
> > hard plaster and rubbed with a painted finish.
> >
> > My question is, do I need to put anything on them to
> > prevent the pottery plaster from sticking forever?
> > This is the first time I've tried this and I would
> > prefer not to ruin the original pieces.
> >
> > I thought of dusting with talc first but some of the
> > carving is very detailed and the talc might clog it
> > up.
> >
> > Thank-you in advance.
> >
> > Marianne Lombardo
> > Omemee, Ontario, Canada
> >
> >
>
____________________________________________________________________________
__
> > 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.
>
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.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.
>
Longtin, Jeff on fri 31 may 02
Marianne,
One bit of advice: Never presume plaster on plaster won't stick to itself
regardless of surface coat. A somewhat simple test to see if the top coat is
porous is to put a drop of water on the surface and watch to see if the
color darkens after a few minutes. If the color darkens, or the drop
disappears, you know defintely the paint is porous and needs sealing. If the
color does not darken you could MAYBE presume it is sealed but I wouldn't
bank on it.
When it comes to molding precious originals I always take the conservative
route.
As Jules mentioned vaseline is a good sealer in such a situation. Its quick.
I might also consider a few coats of Murphy's Oil Soap. You could as well be
extra cautious and spray a few coats of poly-urethane just to be sure
(before you apply any vaseline that is). Its your call on that.
F.Y.I. I always take the cautious route because I'm the guy you're sent to
after the first mold-maker screws up. As such I take the extra step just to
make SURE the piece is not damaged. I charge more than the other guys, of
course, but I've not lost a piece yet!
Sometimes customers will decide to seal the piece themselves to save money.
Sometimes I've trusted that they did what I recommedded. You can guess what
has happened. Now I always calculate sealing time into the price just to be
safe!
I've never heard of using talc as a seperating compound for plaster on
plaster. Talc is used to prevent clay from sticking to the mold surface but
it is never used to prevent plaster from sticking to plaster.
Take care
Jeff Longtin
Complex Molds Made Easy
-----Original Message-----
From: Marianne Lombardo [mailto:mlombardo@NEXICOM.NET]
Sent: Thursday, May 30, 2002 10:37 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Plaster Mold Question Re Sticking
I have two small 3" relief carved disks that I wish to pour plaster over to
make a negative impression. They look like they are made of some sort of
very hard plaster and rubbed with a painted finish.
My question is, do I need to put anything on them to prevent the pottery
plaster from sticking forever? This is the first time I've tried this and I
would prefer not to ruin the original pieces.
I thought of dusting with talc first but some of the carving is very
detailed and the talc might clog it up.
Thank-you in advance.
Marianne Lombardo
Omemee, Ontario, Canada
____________________________________________________________________________
__
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.
Marianne Lombardo on fri 31 may 02
Thanks to all that responded to my question about plaster molds sticking to
pottery plaster.
I've been experimenting with it for about 5 hours so far. I tried vaseline,
cooking spray, and butter. I'm almost there. But some of the very small
detail is breaking off when I take the original form out of the plaster.
Is it because I am not waiting long enough for the plaster to dry? Someone
had told me to wait only 20 minutes to half hour. The plaster is very soft.
At least I've been able to clean it off of the original form okay.
Marianne Lombardo
Suzanne Tourtillott on mon 3 jun 02
Try Murphy's Oil Soap on the object you wish to cast in plaster.
Suzanne
Longtin, Jeff on mon 3 jun 02
Hey Marianne,
Hope your adventures in Plasterland were successful!
I'll just toss you some thoughts on why the detail could be breaking for
future reference.
It could be related to set time, yes, it could also be related to other
factors as well.
With fine detail its really important to brush off, and allow to dry, your
parting compound. Sometimes the parting compound lather can remain in small
crevices so its really important to check this before you pour. Excess or
wet lather residue can contaminate the top layer of plaster and make it
prone breakage and/or softness.
Water temperature can sometimes play a factor. Especially during winters
here in Minnesota normal cold tap water can be quite cold. Cold water slows
down your set times. Warm water,conversely, speeds up set times. I find
tepid water best. If you are forced to use cold water than you need to
lengthen your set times.
Probably a more likely cause of breakage could have been inadequate mixing.
Its really important to mix the plaster at least 2 minutes.
The mix cycle I use: 1) sift plaster into water-allow to sit 2 minutes
2) mix agressively for 2 minutes
3) allow to sit 1 minute.
After this 5 minute period I check consistency. If the mix is still rather
thin/watery I swirl the plaster around in the bucket for a couple of
minutes. I like to pour when the mix has a somewhat thickened quality to it,
(similar to heavy cream). This assures a nice strong mold. Good detail, no
chipping. New plaster, by the way, tends to set more slowly than old
plaster.
Sometimes if I'm mixing large quanities of new plaster, 5 gallons or more, I
may extend the mix cycle to as much as 10 minutes. The more you mix the
stronger the mold.
Sometimes with a small amount of plaster, a quart or less, its hard to mix
aggressively, hence more breakage.
Good Luck
Jeff Longtin
Complex Molds Made Easy
-----Original Message-----
From: Marianne Lombardo [mailto:mlombardo@NEXICOM.NET]
Sent: Friday, May 31, 2002 12:41 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Plaster Mold Question Re Sticking
Thanks to all that responded to my question about plaster molds sticking to
pottery plaster.
I've been experimenting with it for about 5 hours so far. I tried vaseline,
cooking spray, and butter. I'm almost there. But some of the very small
detail is breaking off when I take the original form out of the plaster.
Is it because I am not waiting long enough for the plaster to dry? Someone
had told me to wait only 20 minutes to half hour. The plaster is very soft.
At least I've been able to clean it off of the original form okay.
Marianne Lombardo
____________________________________________________________________________
__
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.
Rob House on tue 4 jun 02
When making a plaster mold, first make sure the object is draftable or
figure out how to construct your mold so it can be removed.
Wet plaster will absorb the talc.
Vaseline is good, but will tend to clog up details.
I like using Murphy's Oil Soap as a mold-release.
Brush / spray it on thin, but with complete coverage.
It forms a nice plaster resistant layer.
Don't pour plaster over anything that won't come back out (e.g. undercuts,
loops). Consider altering any such features in your original with
plasticine (i.e. make it draftable)
Lemme know if you've any further questions.
ENJOY - - - - Rob House
www.robhouse.com
__________________________________________________________
On Thu, 30 May 2002 20:11:23 -0700, Julie Milazzo
wrote:
>Hmmm... what about vaseline? I know that it works for
>plaster molds of faces... Jules
>
>
>--- Marianne Lombardo wrote:
>> I have two small 3" relief carved disks that I wish
>> to pour plaster over to make a negative impression.
>> They look like they are made of some sort of very
>> hard plaster and rubbed with a painted finish.
>>
>> My question is, do I need to put anything on them to
>> prevent the pottery plaster from sticking forever?
>> This is the first time I've tried this and I would
>> prefer not to ruin the original pieces.
>>
>> I thought of dusting with talc first but some of the
>> carving is very detailed and the talc might clog it
>> up.
>>
>> Thank-you in advance.
>>
>> Marianne Lombardo
>> Omemee, Ontario, Canada
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