Stephani Stephenson on tue 1 aug 06
Wendy:
2 suggestions/questions:
1. think the reverse of suction,i.e. forced air...compressed air
tease air nozzle around the line where the model meets the mold
i.e. direct a stream of air in the crack between the two and it should
pop out.
Of course, any undercuts may
prevent the model from releasing from the mold
2. not sure of the shape you are using , but have you thought of using
the polymer clay without baking it?
It holds its shape pretty well , releases from plaster and is flexible.
3. other release agents include vaseline , WD-40 , mold soap, cheap
dish soap,and professioanl grade release agents...
but if one of the first 2 suggestions work...shouldn't need a release
agent
cheers!
Stephani Stephenson
steph@revivaltileworks.com
http://www.revivaltileworks.com
Wendy Kelsey on tue 1 aug 06
I have been making some plaster molds and having trouble
with removing my originals. The originals are made from
polymer clay that has been baked to the specifications of
the manufacturer.
I have tried PAM, and Murphys's Soap. The Murphy's soap
leaves bubbles in the mold and the Pam sort of works but I
still can't get the item out without destroying it as I
kind of dig it out.
Has anyone used suction to remove items? All ideas
appreciated.
Thanks all!
Wendy Kelsey
Operations Manager
Martini Ceramics
Custom Tile and Ceramic Arts
1272 Paradise Cove
Ferndale, WA 98248-9469
Telephone: 360-392-8607
Fax: 832-550-4856
Jacqueline Miller on tue 1 aug 06
Wendy: Try putting the Murphy's on in very thin layers. Jackie
On 8/1/06, Wendy Kelsey wrote:
>
> I have been making some plaster molds and having trouble
> with removing my originals. The originals are made from
> polymer clay that has been baked to the specifications of
> the manufacturer.
>
> I have tried PAM, and Murphys's Soap. The Murphy's soap
> leaves bubbles in the mold and the Pam sort of works but I
> still can't get the item out without destroying it as I
> kind of dig it out.
>
> Has anyone used suction to remove items? All ideas
> appreciated.
>
> Thanks all!
>
> Wendy Kelsey
> Operations Manager
> Martini Ceramics
> Custom Tile and Ceramic Arts
> 1272 Paradise Cove
> Ferndale, WA 98248-9469
> Telephone: 360-392-8607
> Fax: 832-550-4856
>
>
> ______________________________________________________________________________
> 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.
>
--
Jackie Miller
JackieAMiller@gmail.com
Snail Scott on tue 1 aug 06
At 07:33 AM 8/1/2006 -0700, you wrote:
>...I
>still can't get the item out without destroying it as I
>kind of dig it out.
It doesn't sound like a failure in the
mold release, honestly. Are you allowing
for sufficient draft? Vertical surfaces
are not technically undercuts, but they
create far too much friction to allow
easy removal from the mold. A few degrees
angle from vertical is necessary. When I
teach moldmaking, I put a paper cup upside-
down on the table, as a visual referent of
how far from vertical it needs to be. Some
purposes may allow a steeper angle, but
the 'dixie cup' rule of thumb has worked
well for me in most cases. It's more
angle than needed some of the time, but
it's never less.
Another 'hang-up' is often at the bottom
edge of the piece. If the pattern has a
slight curvature there, allowing plaster
to creep under the pattern even a tiny bit,
that's still an undercut that will make
it hard to remove the pattern. It's a
frequently overlooked detail. This small
lip can be cut away in the plaster, but
making sure that the lower edge of the
pattern touches the bottom board/tabletop
squarely (better yet, with a few degrees
of draft) is easy.
When you make your pattern, consider adding
a finger-hole or some such, or loops of
string or wire to help pull it loose from
mold.
I'd stick with soap as a mold release. Unlike
greasy release agents like cooking spray, it
won't interfere with the absorbency of the
plaster mold.
-Snail
John Rodgers on tue 1 aug 06
With your models being made of polymer clay, and assuming you have no
undercuts in the model, there are a couple of things you can do.
Spray the model with a polyurethane spray paint to seal the surface. Two
to three thin coats, allowing to dry thoroughly in between each coat.
Depending on the surface, I may use 4-0 steel wool applied gently to
smooth the surface, or worn-out 600 grit wet/dry sand paper. Always use
the wet mode, never sand dry.
Mold release - I have for years used tincture of green soap cut 50-50
with water. I have used many other mold release compounds but green soap
has proved to be the best for me. I apply gently with a
squeezed-out-but-not-dry real sponge or piece there-of. Work a lather on
the surface of the piece. Allow to dry, or mostly dry, then dry brush
with a china/pig bristle brush. Do this process three times. Be sure
that when you brush there are no shiny spots. Shiny spots are soap spots
that are not dry, and they will cause the plaster to curddle. The
cheapo throw-away brushes at the hardware store are usually this type. I
personally use a 3 inch art painting brush - china bristle - costing
about $15 each. I use two of them in the molding process. I make lots of
molds and the brushes last a long time. But the cheapo brushes are good
for small projects. Their only drawback is they tend to shed
bristles.The bristles will build up a residue but they can be cleaned
easily in methanol alcohol and then washed in clean warm. I wash in
alcohol, then water, then clean alcohol again. The last alcohol wash
picks up what water remains in the brush, and eveporates rapidly leaving
a dry brush ready to use in short order.
A very light mist of polyurethane mold release agent as used with
molding rubber compounds might be used to enhance separation. I have
done it, but found that the first casting in the mold is usually toast
and you must through it away. Those being done later are fine.
Alternative mold release. Depending on what you are molding, you can use
Murphy's Oil Soap, PAM, vaseline. These may be used if the mold being
produced is not to be a slip casting mold. These don't work well for
slip casting molds.
Mold Separation: - The point to the mold soap is to make a dry soap seal
over the model and when ready, the dry soap will allow the model and the
new mold to release. The optimum time to remove a mold from the model -
or vice sersa - is when the mold has reached the highest temperature of
hydration. This is the heat generated by the chemical reaction of the
lime in the plaster to the water that it is mixed into. When the mold is
very warm, the soap seal will soften, and moisture from the plaster will
further soften it, and allow an easy release. You can separate them
later, but it's easiest and best done when the mold is warm.
Sometimes compressed air can be applied right at the seam and the two
pieces will separate. Sometimes not. And then you get out the rubber
mallet and some wooden wedges, it just all depends on the circumstances.
I have made models with holes in them so I could force compressed air
through the holes to get the mold to separate. Some times it has been
the other way around. The mold had the holes. You just try different ways.
Good luck.
John Rodgers
Chelsea, Al
Wendy Kelsey wrote:
> I have been making some plaster molds and having trouble
> with removing my originals. The originals are made from
> polymer clay that has been baked to the specifications of
> the manufacturer.
>
> I have tried PAM, and Murphys's Soap. The Murphy's soap
> leaves bubbles in the mold and the Pam sort of works but I
> still can't get the item out without destroying it as I
> kind of dig it out.
>
> Has anyone used suction to remove items? All ideas
> appreciated.
>
> Thanks all!
>
> Wendy Kelsey
> Operations Manager
> Martini Ceramics
> Custom Tile and Ceramic Arts
> 1272 Paradise Cove
> Ferndale, WA 98248-9469
> Telephone: 360-392-8607
> Fax: 832-550-4856
>
> ______________________________________________________________________________
> 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.
>
>
>
Cindy Gatto on tue 1 aug 06
Get mold soap from any ceramic supply house That is what it is made for.
That is the only thing we use It always works we have never had a problem
Cindy Gatto & Mark Petrin
The Mudpit
228 Manhattan Ave
Brooklyn, NY 11206
718-218-9424
_www.mudpitnyc.com_ (http://www.mudpitnyc.com/)
mudpitnyc@aol.com
Cindy Gatto on tue 1 aug 06
Another thing you can try is spraying the model with polyurethane. I have
never casted polymer clay but your problem could be the piece not being sealed
It doesn't show up on anything it just seals the piece so it's worth the try.
Make sure the polyurethane is dry before casting. Then use mold soap. Sorry I
thought of this after I hit the send button on the first post.Good luck
Cindy Gatto & Mark Petrin
The Mudpit
228 Manhattan Ave
Brooklyn, NY 11206
718-218-9424
_www.mudpitnyc.com_ (http://www.mudpitnyc.com/)
mudpitnyc@aol.com
Jean Cochran on tue 1 aug 06
Hi Ya'll,
My plaster molds release because plaster absorbs the moisture from the clay
and it shrinks away from the plaster. Putting a mold release on it, seems
to me to defeat the purpose
Jean Wadsworth Cochran
www.foxhollowpottery.com
www.kycraft.ky.gov/craftcgi-bin/index.cgi?busid=186
marianne kuiper milks on wed 2 aug 06
Well, a mixture of water and bleach is said to release the mold.
Sorry - couldn't 'resist".
Hope you find a good outcome, or just let it go. :-[)
Marianne
Thermometer on our little mountain at 101º. Keep all windows covered, doors shut, fan toward the ceiling. We have no AC but our solid stone's house temp was about 78º all day. Quite comfortable. Fill the tub and jump in.
Wendy Kelsey wrote: I have been making some plaster molds and having trouble
with removing my originals. The originals are made from
polymer clay that has been baked to the specifications of
the manufacturer.
I have tried PAM, and Murphys's Soap. The Murphy's soap
leaves bubbles in the mold and the Pam sort of works but I
still can't get the item out without destroying it as I
kind of dig it out.
Has anyone used suction to remove items? All ideas
appreciated.
Thanks all!
Wendy Kelsey
Operations Manager
Martini Ceramics
Custom Tile and Ceramic Arts
1272 Paradise Cove
Ferndale, WA 98248-9469
Telephone: 360-392-8607
Fax: 832-550-4856
______________________________________________________________________________
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.
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