Glass Casting Experiments... Advice needed (I'm out of the office Monday, January 31st but I will be back on Tuesday, February 1st. )

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Laura L Dawson

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Jan 29, 2000, 3:00:00 AM1/29/00
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Hello :)

My name is Heather and I live in South West England... I am an artist
designer and I am thinking of experimenting with melting glass...

I do a fair bit of pottery and am thinking of taking glass pieces and
melting them in my kiln... the idea being that the glass pieces would be
placed in fragments in an open topped mould and as the glass melts it
would fill the mould... (the mould would be some simple design like a
leaf or fish shape with simple decoration)... the mould I plant to make
from stoneware clay...
I am planning to use bottle glass, from white, blue, brown and green
wine bottles as the glass to use...


Now I have some thoughts here for you clever people who know all about
glass things :) :)...

1.
would the glass melt and stick to the clay because it would get very hot
and runny and might boil and would not be able to separate from the
clay?

2.
would the glass melt as I want, slide into the mould and then as it
cools, separate from the clay mould leaving me with a glass fish shaped
pendant?

3.
how would moltern glass behave in a pottery kiln?
what kind of temperature would I need to create the effect I want where
the glass might melt and not stick to the clay?
My average pottery firings are anything between 1050 and 1250 degree's.
Pretty hot ugh :) but I can go lower to suit glass.

4.
Am I a completely mad scatterbrained blonde woman who is wasting her
time? :)

Any feedback on my crazy experimental idea would be interesting!

Thanks folks :)


***********************************************************

"Dream the surreal... then with wisdom go out and live it!"

<Heather Coleman Dec. 1999>

***********************************************************

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Laura L Dawson

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Heather Coleman wrote in message ...


>
>1.
>would the glass melt and stick to the clay because it would get very hot
>and runny and might boil and would not be able to separate from the
>clay?
>
>2.
>would the glass melt as I want, slide into the mould and then as it
>cools, separate from the clay mould leaving me with a glass fish shaped
>pendant?
>
>3.
>how would moltern glass behave in a pottery kiln?
>what kind of temperature would I need to create the effect I want where
>the glass might melt and not stick to the clay?
>My average pottery firings are anything between 1050 and 1250 degree's.
>Pretty hot ugh :) but I can go lower to suit glass.
>

Heather, your first problem is that the glass will almost certainly wet the
clay mould, like a glaze does, and you will not be able to separate them.
Depending on the glass chemistry, you may also get release of dissolved
gases as you heat up the glass. Like with glazes, you can get lots of bubble
formed due to reboil. The risk is highest with amber.

The glass will start to soften at about 650C and is normally formed by
blowing or pressing at temperatures in the range of 1050-1200C, depending on
the process and size of the object being formed.

You may do better to use a metal mould, and possibly think of melting the
glass in your kiln, then pouring it from a small pot into the mould, or even
pressing it with a simple mould. You would need refractory pots to do this
re-melting, and tongs to lift them out of your kiln. 1250C may just be
enough to get a decent melt, which needs time and temperature. If you are
pouring or pressing, that may be a good working temperature for a small
article, but cooler may be better.

Give me a call if you like.
--
Terry Harper, Web Co-ordinator, The Omnibus Society
http://www.omnibussoc.org
E-mail: terry....@btinternet.com
URL: http://www.btinternet.com/~terry.harper/


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Laura L Dawson

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>>> "rec.craf...@list.deja.com" 01/22/00 18:21 >>>

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In article <ZzhHnEAc...@dawnmist.demon.co.uk>,


Heather Coleman <hea...@dawnmist.demon.co.uk> wrote:
>
> Hello :)
>
> My name is Heather and I live in South West England... I am an artist
> designer and I am thinking of experimenting with melting glass...
>
> I do a fair bit of pottery and am thinking of taking glass pieces and
> melting them in my kiln... the idea being that the glass pieces would
be
> placed in fragments in an open topped mould and as the glass melts it
> would fill the mould... (the mould would be some simple design like a
> leaf or fish shape with simple decoration)... the mould I plant to
make
> from stoneware clay...
> I am planning to use bottle glass, from white, blue, brown and green
> wine bottles as the glass to use...
>
> Now I have some thoughts here for you clever people who know all about
> glass things :) :)...
>

> 1.
> would the glass melt and stick to the clay because it would get very
hot
> and runny and might boil and would not be able to separate from the
> clay?
>
> 2.
> would the glass melt as I want, slide into the mould and then as it
> cools, separate from the clay mould leaving me with a glass fish
shaped
> pendant?
>
> 3.
> how would moltern glass behave in a pottery kiln?
> what kind of temperature would I need to create the effect I want
where
> the glass might melt and not stick to the clay?
> My average pottery firings are anything between 1050 and 1250
degree's.
> Pretty hot ugh :) but I can go lower to suit glass.
>

> 4.
> Am I a completely mad scatterbrained blonde woman who is wasting her
> time? :)
>
> Any feedback on my crazy experimental idea would be interesting!
>
> Thanks folks :)
>
> ***********************************************************
>
> "Dream the surreal... then with wisdom go out and live it!"
>
> <Heather Coleman Dec. 1999>
>
> ***********************************************************

No offense, you seem like a nice lady, but... I think most who post to
this group would agree, you need to read a few books, maybe take a
class, do some experiments, then write back with specific questions.
people will be glad to help you. In general, what you have envisioned is
possible. but the range of processes is vast and techically involved
making them impossible to explain to a person with zero kno


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Laura L Dawson

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Jan 29, 2000, 3:00:00 AM1/29/00
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>>> "rec.craf...@list.deja.com" 01/22/00 20:50 >>>

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Well, Terry, the problem is that if you had read her post, although she
talks about molten
glass, what she wants to do is nothing more than ordinary fusing,
putting pieces of glass in
a mold and melting them together.
It is done every day by hundreds of people and lots of them are using
clay molds, which work
fine as long as the glass is not incredibly hot and they are coated with
kiln wash like Paragon
sells.
This is not a major interest of mine, but if you glance that this page
http://ourworld.compuserve.com/homepages/MikeFirth/mfgl.htm of my web
site, you will see in the middle of the first picture, a fused piece
made by placing pieces of bottle glass on a clay mold covered with kiln
wash separator. The mold was made by pressing thin rolled potters white
clay into an aluminum tea cookies mold and letting it dry, then firing
it above the temp for the fusing (fusing about 1500F, firing to about
1800F)
I recommended Boyce Lundstroms books to her.
Warm Glass, as a category, is hot right now, and slumping, fusing,
pate d'verre, and kiln casting are all possible without turning the
glass molten in advance, which is glass casting and is a whole lot
tougher on the pocket book, like furnace glassblowing.

Terry wrote


<<Heather, your first problem is that the glass will almost certainly
wet the

clay mould, like a glaze does, and you will not be able to separate


them.
Depending on the glass chemistry, you may also get release of dissolved
gases as you heat up the glass. Like with glazes, you can get lots of
bubble
formed due to reboil. The risk is highest with amber.

The glass will start to soften at about 650C and is normally formed by
blowing or pressing at temperatures in the range of 1050-1200C,
depending on
the process and size of the object being formed.

You may do better to use a metal mould, and possibly think of melting
the
glass in your kiln, then pouring it from a small pot into the mould, or
even
pressing it with a simple mould. You would need refractory pots to do
this
re-melting, and tongs to lift them out of your kiln. 1250C may just be
enough to get a decent melt, which needs time and temperature.>>

--

Mike Firth
Hot Glass Bits newsletter and furnace glass information web site
http://ourworld.compuserve.com/homepages/MikeFirth/

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Laura L Dawson

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Jan 29, 2000, 3:00:00 AM1/29/00
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>>> "rec.craf...@list.deja.com" 01/22/00 21:26 >>>

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In article <ZzhHnEAc...@dawnmist.demon.co.uk>, Heather Coleman
<hea...@dawnmist.demon.co.uk> wrote:


>
> Hello :)
>
> My name is Heather and I live in South West England... I am an artist
> designer and I am thinking of experimenting with melting glass...
>
> I do a fair bit of pottery and am thinking of taking glass pieces and
> melting them in my kiln... the idea being that the glass pieces would be
> placed in fragments in an open topped mould and as the glass melts it
> would fill the mould... (the mould would be some simple design like a
> leaf or fish shape with simple decoration)... the mould I plant to make
> from stoneware clay...
> I am planning to use bottle glass, from white, blue, brown and green
> wine bottles as the glass to use...
>
>
> Now I have some thoughts here for you clever people who know all about
> glass things :) :)...
>
> 1.
> would the glass melt and stick to the clay because it would get very hot

> and runny and might boil and would not be able to separate from the
> clay?

You need a kiln wash or glass seperator. It needs to be applied freshly
before each firing to fusing temperatures. 80% flour of alumina hydrate 20%
kaolin. I don't know the maximum temperature this works at. I do know it
works at 1500*F.

>
> 2.
> would the glass melt as I want, slide into the mould and then as it
> cools, separate from the clay mould leaving me with a glass fish shaped
> pendant?

Glass shrinks more than clay. Most kiln casters use a plaster based
investment to cast in.


>
> 3.
> how would moltern glass behave in a pottery kiln?
> what kind of temperature would I need to create the effect I want where
> the glass might melt and not stick to the clay?
> My average pottery firings are anything between 1050 and 1250 degree's.
> Pretty hot ugh :) but I can go lower to suit glass.

You will find bottle glass to be very difficult to get a good looking
result. Generally kiln casting is done with either lead crystal or highly
fluxed casting glass. These glasses melt at a lower temperature than bottle
glass and flow much easier. Get a book. like Boyce Lundstrom's "Glass
Casting and Mold Making"

Go for it.

Bert

Bert Weiss Art Glass
http://www.customartglass.com
Furniture Sculpture Lighting Tableware
Architectural Commissions
Collaborative Art Glass Projects

>
> 4.
> Am I a completely mad scatterbrained blonde woman who is wasting her
> time? :)
>
> Any feedback on my crazy experimental idea would be interesting!
>
> Thanks folks :)
>
>
> ***********************************************************
>
> "Dream the surreal... then with wisdom go out and live it!"
>
> <Heather Coleman Dec. 1999>
>
> ***********************************************************

_____________________________________________________________


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Smith

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Jan 29, 2000, 3:00:00 AM1/29/00
to
Heather -

It is refreshing to hear from someone that is in the "Experimenting
Mode" What you
have described, I have seen done, and with very good results I might add.
As with what
one of the other posters said, a book on Kilm Casting would be of a great
benefit if you
want to pursue this beyond this experiment stage. Please see notes below.

> Hello :)
> My name is Heather and I live in South West England... I am an artist
> designer and I am thinking of experimenting with melting glass...
> I do a fair bit of pottery and am thinking of taking glass pieces and
> melting them in my kiln... the idea being that the glass pieces would be
> placed in fragments in an open topped mould and as the glass melts it
> would fill the mould... (the mould would be some simple design like a
> leaf or fish shape with simple decoration)... the mould I plant to make
> from stoneware clay...
> I am planning to use bottle glass, from white, blue, brown and green
> wine bottles as the glass to use...

----- Try to use the same types of glass from the same "Brand" of wine if
you will.
Mixing the different glasses will result most likely in failure as they tend
to be
very incompatible with each other. Different glasses from different
container
manufactuerers are as different as the wine that is in each. Keep greens
with
greens, blues with blues, etc.

> Now I have some thoughts here for you clever people who know all about
> glass things :) :)...
> 1.
> would the glass melt and stick to the clay because it would get very hot
> and runny and might boil and would not be able to separate from the
> clay?

----- Use a kilnwash type of release on you molds. Kilnwash will allow the
glass
to release from the mold, however, leaves a somewhat frosty finish on the
glass.
Many of the pieces that I have seen come from a process like this end up
getting
sand blasted/etched anyway. At any rate, your clay moulds will probably
only hold up
a couple of times in this process, and you will have to pitch them.

> 2.
> would the glass melt as I want, slide into the mould and then as it
> cools, separate from the clay mould leaving me with a glass fish shaped
> pendant?

----- Yes, this is the exact process. Some of the moulds that I have seen
have
a funnel on top so as the glass drains into the mould, more glass is added
on top.

> 3.
> how would moltern glass behave in a pottery kiln?
> what kind of temperature would I need to create the effect I want where
> the glass might melt and not stick to the clay?
> My average pottery firings are anything between 1050 and 1250 degree's.
> Pretty hot ugh :) but I can go lower to suit glass.

----- If you can get to 1500 F/840 C, this is ideal for melting the glass.
Once you
get the glass melted and into the mould, then the next series of steps are
to
anneal and cool the glass, which you could have some beginner's luck, or
never
master. This is where that book comes in as it will tell you exactly what
to do,
providing your equipment is capable of doing so. Also using recycled glass
can
complicate this matter as you won't know some of the specific properties of
the
glass: anneal, strain, melting, softening temps.

> 4.
> Am I a completely mad scatterbrained blonde woman who is wasting her
> time? :)

-----All you need to be an inventor is a good imagination and a pile of
junk..... I have more
respect for the fellow with a single idea who gets there than for the fellow
with a
thousand ideas who does nothing.....Nearly every man who develops an idea
works
it up to the point where it looks impossible, and then gets discouraged.
That's not
the place to become discouraged......

......Thomas Edison


Hope this helps.....Good Luck


> Any feedback on my crazy experimental idea would be interesting!
>
> Thanks folks :)
>
>
> ***********************************************************
>
> "Dream the surreal... then with wisdom go out and live it!"
>
> <Heather Coleman Dec. 1999>
>
> ***********************************************************
>
>
>
> _____________________________________________________________
> Deja.com: Before you buy.
> http://www.deja.com/
> * To modify or remove your subscription, go to
> http://www.deja.com/edit_sub.xp?group=rec.crafts.glass
> * Read this thread at
>

http://www.deja.com/thread/%3CZzhHnEAcqgi4IwR%2B%40dawnmist.demon.co.uk%3E

Laura L Dawson

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Jan 29, 2000, 3:00:00 AM1/29/00
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Mike Firth wrote in message
<3254BF5DD4B8B816.5892B2FE...@lp.airnews.net>...


> Well, Terry, the problem is that if you had read her post, although she
>talks about molten
>glass, what she wants to do is nothing more than ordinary fusing,
>putting pieces of glass in
>a mold and melting them together.
> It is done every day by hundreds of people and lots of them are using
>clay molds, which work
>fine as long as the glass is not incredibly hot and they are coated with
>kiln wash like Paragon
>sells.


OK, but that's not how it read.

I bow to those learned in the black art of fusion.


--
Terry Harper, Web Co-ordinator, The Omnibus Society
http://www.omnibussoc.org
E-mail: terry....@btinternet.com
URL: http://www.btinternet.com/~terry.harper/

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Terry Harper

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Jan 31, 2000, 3:00:00 AM1/31/00
to
Smith wrote in message ...

>
>----- Try to use the same types of glass from the same "Brand" of wine if
>you will.
>Mixing the different glasses will result most likely in failure as they
tend
>to be
>very incompatible with each other. Different glasses from different
>container
>manufactuerers are as different as the wine that is in each. Keep greens
>with
>greens, blues with blues, etc.
>
Ideally you would use glass from the same furnace. The punt marks will be a
guide, but not necessarily to the furnace in use. In some cases, like
Beatson Clark or Lewis & Towers, you can be certain that all the amber comes
from the same furnace, because they only have the one. However UG, Rockware
or PLM-Redfearn have more than one furnace on amber.

The glass chemistry may not be the same in different furnaces, because they
may be on different sites in some cases.

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