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Can You Make A Plaster Mold Of Glass?


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#1 Magnet

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Posted 17 March 2017 - 07:33 PM

My subject says it all. I've done it with plastic and of course ceramic, but I'd like to make a one-part mold of a glass that I have. Simple cup, no undercut. If it were plastic I'm sure it would work perfectly.

I've made many molds before, just never out of glass -- so I'm hoping that someone has experience with this so I won't waste time on an unfruitful endeavor.

I'd appreciate any experienced advice. Thanks!

#2 oldlady

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Posted 17 March 2017 - 07:48 PM

my attempt  was unsuccessful.  mostly because i could not find a separating agent that worked.  that attempt was to put the plaster inside the glass baking dish.  i may have used a glass dish with a slight undercut as well.  not a good experience.  

 

later, i used a handmade glass form for a slump mold.  it worked well but the handmade nature of the glass form was uneven and i was not happy with the final plate.  good luck.


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#3 Infinite

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Posted 18 March 2017 - 02:17 AM

I've made serveral plaster molds of glass cups and they were fine. So I think you should definitely give it a try.


Form is the possibility of structure -tractatus logico; Ludwig Wittgenstein-


#4 Chilly

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Posted 18 March 2017 - 02:41 AM

Yes.

gallery_59202_704_28309.jpg

Taken from Lark Ceramic's "The Essential Guide to Mold Making & Slip Casting".


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#5 Sputty

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Posted 18 March 2017 - 03:29 AM

Ann - that is a very useful table! Thanks for reproducing it here.

Have you ever seen a source for oil clay in the UK (or elsewhere in Europe)?

(I admit to not looking very hard, and also to being lazy...)

 

 

EDIT: -------------------------------------------------------

 

To answer my own question, pottery suppliers are not the place to look; art suppliers are. Found loads of sources, most of whom deal with sculpture rather than ceramics per se.

 

See. Not so lazy after all.



#6 Magnet

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Posted 18 March 2017 - 07:39 AM

Sweet! Thanks a heap for the considered answers and that excellent chart.
Now, to the plaster!

#7 Marcia Selsor

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Posted 18 March 2017 - 07:44 AM

I have made molds of large glass convex light shades. I used vaseline and another time WD-40.
Marcia
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#8 High Bridge Pottery

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Posted 18 March 2017 - 08:01 AM

Ann - that is a very useful table! Thanks for reproducing it here.

Have you ever seen a source for oil clay in the UK (or elsewhere in Europe)?

(I admit to not looking very hard, and also to being lazy...)

 

 

EDIT: -------------------------------------------------------

 

To answer my own question, pottery suppliers are not the place to look; art suppliers are. Found loads of sources, most of whom deal with sculpture rather than ceramics per se.

 

See. Not so lazy after all.

 

Isn't oil clay just called Plasticine?

 

I have made one parts using a glass. Few mistakes I made, first time the glass was full of air and when I poured plaster it came unstuck from the base. Now I made that mistake the glass was full of plaster so no air pocket to lift up the glass any more so you win and lose. Make sure to add soap otherwise it is impossible to get the glass out. 


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#9 Sputty

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Posted 18 March 2017 - 08:41 AM

 

Isn't oil clay just called Plasticine?

 

 

I think Plasticine might be considered to be an oil clay, but oil clay is not necessarily Plasticine (as we know it from our extended childhoods).

The 'serious' stuff is a bit more refined, I think. But I might be wrong; it has been known.

 

NSP Professional Oil Based Clay



#10 Mark C.

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Posted 18 March 2017 - 11:20 AM

glass is easy to make a mold from-just get a good release.


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www.liscomhillpottery.com

#11 Stone Spiral

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Posted 20 March 2017 - 11:14 PM

What would you use as "soapy release"? I am going to try this this week - I have a large, gorgeous glazed porcelain bowl that I would like to make a mold of. I want to make sure I put the right release agent on it, so that I don't damage the beautiful bowl in the separation process.


~* Roxy *~


#12 Chilly

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Posted 21 March 2017 - 02:28 AM

What would you use as "soapy release"? I am going to try this this week - I have a large, gorgeous glazed porcelain bowl that I would like to make a mold of. I want to make sure I put the right release agent on it, so that I don't damage the beautiful bowl in the separation process.

 

I bought mine from a pottery supply place.  It's like jelly, and needs mixing 50:50 with water.  

 

I've read that you can use Murphy's Oil Soap? but not found that in the UK.  Also heard of people using dishwashing liquid, but you need it to be quite thick.

 

Found this through good old google:  https://books.google...release&f=false


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#13 Mark C.

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Posted 21 March 2017 - 10:18 AM

http://www.axner.com/pure-lube.aspx


Mark Cortright
www.liscomhillpottery.com




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