Dear Sirs
Hi I am looking for some info on glass molds for blowing.
I work for a large Lamp Co in Miami Fl one of our dept is a glass
blowing and slumping.Myself I only know a little about glass as my
background is mold making ceramic, silicone and the like. Even thou I
helped set up the glass dept and build the glass tanks and use to
charge the glass at night before leaving that is about as far as my
knowledge goes. When we first started to do glass we were melting
marbles in side our ceramic kilns. I was making the one use waste molds
for the glass out of plaster EPK and vermiculite some one found the mix
in a glass book. That guy is long gone and I don't have the formula
any more it has been like 9 years since we needed molds like that. The
glass dept moved on to machined Graphite molds and metal molds. So my
hands have been out of the glass for around 6 years.
Do you have any idea were I can find the formula? (plaster EPK and
vermiculite mix) Book web site or do you know of it and can please you
share it.

Next they are looking at the cost of the metal molds we have to have
made 2 to 3 thousands dollars each and they are looking to find a cheep
way to make the molds so I was ask to look for fast easy ways to make
the molds. I have some ideas and I am wondering if they will work or if
you or any one you know has tried them. All the ideas relate to glass
blowing molds. All molds will be from 1 to 4 parts.

1.Ceramic molds like used in slumping the mold will be in 3 to 4 parts.
Because of undercuts.
2.Refractory like ZerCar can it be molded and will it last for say 50
blows.
3.Plaster EPK vermiculite mold.
4.Polyurethane mixed with metal powder
5.Epoxy mixed with metal powder
6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.
7.Do you have any ideas that may be of help.


Thank You
Rodney Rock
Master Mold Maker / Design
Fine Art Lamps
Miami Lakes Florida
Phone 305-821-1055 EX 3065
Work Email
Home Email
Web Address www.fineartlamps.com

wrote in message
ups.com...
Do you have any idea were I can find the formula? (plaster EPK and
vermiculite mix) Book web site or do you know of it and can please you
share it.

The thing about mixes is there isn't a magic thing where it will work, as
opposed to one ounce off and it will suddenly shatter exactly three hours
into setting.

I've never heard of the mix, but gee, just grab some plaster, clay and
vermiculite and start mixing.

I don't know what the requirements are, but personally I'd drop the clay:
it's only going to cause shrinkage on trying.

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

When I worked at the former RCA Laboratories as a co-op student, I hung
around a lot in their glass shop. They mostly produced vacuum tube
envolopes, but these have a great deal of similarity to light bulb
envelopes.

They used machined graphite molds for their blown envelopes, and
graphic templates to shape those turned on a glass lathe.

The tube headers and stems were purchased from an outside vendor, so I
don't know how these were made.

Harry C.

In article . com,
wrote:
Dear Sirs
Hi I am looking for some info on glass molds for blowing.
I work for a large Lamp Co in Miami Fl one of our dept is a glass
blowing and slumping.Myself I only know a little about glass as my
background is mold making ceramic, silicone and the like. Even thou I
helped set up the glass dept and build the glass tanks and use to
charge the glass at night before leaving that is about as far as my
knowledge goes.

In which case, you should probably tone back part of your .sig
for a while -- the part which reads:


================================================== ====================
Master Mold Maker
================================================== ====================

:-)

Actually -- what little I know about glass blowing was done
without molds, and was in chem lab class -- just a bit of starting
glasswork.

1.Ceramic molds like used in slumping the mold will be in 3 to 4 parts.
Because of undercuts.
2.Refractory like ZerCar can it be molded and will it last for say 50
blows.
3.Plaster EPK vermiculite mold.

4.Polyurethane mixed with metal powder

Do you *know* that this is used? It strikes me that the
temperatures would be way too high for something like this to be any
more than a single-shot mold.

5.Epoxy mixed with metal powder

Similar feelings about these -- except that they might handle
two or three -- depending on how well cooled the mold is.

6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.

*Pour* it? Graphite is a crystalline form of carbon. According
to my old copy of the _Handbook of Chemistry and Physics_, carbon's
melting point is 1350 C, and it *sublimes* (that is goes straight from
solid to vapor form) above 1300 C, so if you were to melt it to pour
(neglecting whether it would form the right crystal form on cooling,
instead of diamond or some amorphous form), you would need to do so in
an inert atmosphere, at some significant pressure. The specific gravity
(and thus relative density) is:

amorphous 1.88
graphite 2.25
diamond 3.51

so my guess would be that it would be some variant of amorphous without
a very carefully controlled pattern of temperature and pressure.

Just to put it into perspective, that melting point, which was
given in degrees C (1350) translates to 2462 F -- well above what I can
reach (1850 F) in my metal hardening oven.

In contrast, glass has a temperature of fusion (close enough to
a melting point for our purposes) of 1100 C (2012 F). And, of course,
different glasses will have differing melting points -- but this is
probably close enough to make my point, and it was what I could easily
look up.

Obviously, if glass melted above the melting point of carbon
(graphite) it would be of little use to you as a mold.

7.Do you have any ideas that may be of help.

For the shaping of the graphite molds, you will want to start
with sold blocks of graphite, and machine away parts to make your mold.
You may be able to do it with a lathe, but a milling machine would be
a better choice -- and a CNC milling machine would probably be the best
choice to get precise shapes. This will require someone to learn how to
run and to program one.

You *could* use a burr in a die grinder to cut the shapes by
hand, but this would make it more difficult to make the halves (or more
parts) of the mold meet properly. This might be reasonable for an
experiment, but not for production.

And since carbon dust from the machining can be rather abrasive,
depending on how pure the graphite is, you may want to get a CNC milling
machine which is nearly worn out anyway (which will reduce the
acquisition cost, if not that of maintenance).

And they could be used to machine the metal molds as well (and
they would probably live longer doing that.)

I don't know what metals are a proper choice for glass molds,
but it would have to be something which could run at a temperature near
that of the molten glass, so you don't get a sudden cooling and
fracture your workpiece.

Good Luck
DoN.


--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote in message
...
5.Epoxy mixed with metal powder

Similar feelings about these -- except that they might handle
two or three -- depending on how well cooled the mold is.

If they are indeed used, I would suspect the binder burns out (*cough*) on
the surface, leaving a somewhat temp-resistant layer of filler.

6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.

*Pour* it? Graphite is a crystalline form of carbon. According
to my old copy of the _Handbook of Chemistry and Physics_, carbon's
melting point is 1350 C

Whoa! You missed a rather large factor there, DoN. ;-)

Next closest thing I see on my periodic table is either terbium, dysprosium
or silicon. The latter makes the most sense since it's right below carbon.

As for carbon itself, it melts/sublimes (nearly the same at 1atm pressure)
somewhere around 4000°C, or about 7150°F. Just a *little* bit hard to
cast...

(neglecting whether it would form the right crystal form on cooling,
instead of diamond or some amorphous form)

Would be neat if molten carbon crystallized into diamonds, but unfortunately
that takes a lot of pressure, AFAIK. Although I think they've been getting
around the extreme pressure or temperature things with CVD (chemical vapor
deposition), I should read up on the current tech (if it isn't a total trade
secret).

Just to put it into perspective, that melting point, which was
given in degrees C (1350) translates to 2462 F -- well above what I can
reach (1850 F) in my metal hardening oven.

Within reach of a good foundry furnace, though. My graphite-based crucibles
aren't falling apart in the heat, so I think you grabbed the wrong number
;-)

And since carbon dust from the machining can be rather abrasive,
depending on how pure the graphite is

Actually, I'm not sure if purity is the cause. IIRC, "graphite" is made
artificially by heaping ground charcoal or coke, lampblack, other junk and
pitch together into an electric furnace. The pitch decomposes to either
amorphous or graphitic carbon, binding together the mass; the other material
is recrystallized by the intense temperature, forming a polycrystalline
block. I've heard the structure described as nodules, globs, flakes and
other junk. It's still graphite, but it's kinda random I guess, and that's
why it's abrasive.

I imagine natural graphite (probably damned expensive) would be wonderful
stock to machine.

I don't know what metals are a proper choice for glass molds,
but it would have to be something which could run at a temperature near
that of the molten glass, so you don't get a sudden cooling and
fracture your workpiece.

Eh- pressed glass is made in warm (dark red heat, probably 1200°F) cast iron
molds. Worked glass is formed with steel and moistened wood tools!
(Lichtenfrost effect, anyone?)

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.

*Pour* it? Graphite is a crystalline form of carbon.
According
to my old copy of the _Handbook of Chemistry and Physics_, carbon's
melting point is 1350 C, and it *sublimes* (that is goes straight from
solid to vapor form) above 1300 C, so if you were to melt it to pour


Don
I don't want to melt it to pour.I am thinking in a cold cast way
Graphite powder mixed with polyurthane,epoxie, or some other type of
binder.
So I would beable to cast the mix have it set up and be able to blow
glass in it.
Snip:
In which case, you should probably tone back part of your .sig
for a while -- the part which reads:
Master Mold Maker
:-)
It took me a lot years to get that title.As well it only relates to
ceramic molds for ceramic castings,Silicone for resin castings and
latex for plaster castings.But you may have a very good point.
thanks
Rodney

In article . com,
Rodney wrote:
6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.

*Pour* it? Graphite is a crystalline form of carbon.
According
to my old copy of the _Handbook of Chemistry and Physics_, carbon's
melting point is 1350 C, and it *sublimes* (that is goes straight from
solid to vapor form) above 1300 C, so if you were to melt it to pour


Don
I don't want to melt it to pour.I am thinking in a cold cast way
Graphite powder mixed with polyurthane,epoxie, or some other type of
binder.
So I would beable to cast the mix have it set up and be able to blow
glass in it.

Hmm ... I really think that something like that would have
serious problems as anything other than perhaps a one-shot mold -- and
even then I would expect the epoxy or poly-whatever to outgas massively
on contact with the hot glass surface -- both cooling it too quickly
(risking shattering), and perhaps deforming the workpiece with bubbles
formed from contact with the mold's surface.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
Tim Williams wrote:
"DoN. Nichols" wrote in message
...
5.Epoxy mixed with metal powder

Similar feelings about these -- except that they might handle
two or three -- depending on how well cooled the mold is.

If they are indeed used, I would suspect the binder burns out (*cough*) on
the surface, leaving a somewhat temp-resistant layer of filler.

6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.

*Pour* it? Graphite is a crystalline form of carbon. According
to my old copy of the _Handbook of Chemistry and Physics_, carbon's
melting point is 1350 C

Whoa! You missed a rather large factor there, DoN. ;-)

You're right. One of the problems of having to put on glasses
to read the small type in the _Handbook_, and having to take them off to
see the screen at about 24" distance from my eyes.

Re-reading I find 3550 C and 3500 C (6422 F and 6332 F
respectively).

Next closest thing I see on my periodic table is either terbium, dysprosium
or silicon. The latter makes the most sense since it's right below carbon.

As for carbon itself, it melts/sublimes (nearly the same at 1atm pressure)
somewhere around 4000°C, or about 7150°F. Just a *little* bit hard to
cast...

I mentioned the problem of it subliming below the melting point.
And, it looks as though you used one of the extended ASCII characters
for degrees, which displays as '\260' on my screen -- one reason for
avoiding using *any* extended ASCII character -- not everybody sees them
the same.

And we still have a disagreement of melting points (though not
as extreme as before). Mine is from the _Handbook of Chemistry and
Physics, 43rd edition_, (1961-1962). "(Description of) The Elements",
starting page 405, with Carbon on page 410-411. The first few lines
read:

"Carbon (L. icarbo/i, charcoal), C; at. Wt. 12.001; at. no.
6; m.p. 3550 deg C, sublimes above 3500 deg C; b.p. 4200 deg C;
sp. gr. amorphous 1.88, graphite 2.25, diamond 3.51; valence 3,
3, o4 4."

I don't think that the characteristics of Carbon, or our
knowledge of them, have changed that much since 1961. :-)

Forgive me for the use of HTML tags in there, but I was not sure
of any way to show italics to everyone -- some newsreaders may actually
*display* that as italics -- the rest will cue the reader that they
should be italics.

So -- what is the source for *your* figures, now that I have
corrected mine?

(neglecting whether it would form the right crystal form on cooling,
instead of diamond or some amorphous form)

Would be neat if molten carbon crystallized into diamonds, but unfortunately
that takes a lot of pressure, AFAIK.

Yep -- sometimes achieved by surrounding the carbon with steel
which shrinks in the chilling, generating the forces necessary -- but
only for very small diamonds.

Although I think they've been getting
around the extreme pressure or temperature things with CVD (chemical vapor
deposition), I should read up on the current tech (if it isn't a total trade
secret).

That would be interesting. I wonder what happens with vapor
deposition -- assuming that the "boats" can get hot enough to evaporate
carbon. If you started depositing it on a seed diamond, and on
something with a matching crystal lattice, the crystal might grow
nicely.

Just to put it into perspective, that melting point, which was
given in degrees C (1350) translates to 2462 F -- well above what I can
reach (1850 F) in my metal hardening oven.

Within reach of a good foundry furnace, though. My graphite-based crucibles
aren't falling apart in the heat, so I think you grabbed the wrong number
;-)

I did -- or at least typed the wrong one.

And since carbon dust from the machining can be rather abrasive,
depending on how pure the graphite is

Actually, I'm not sure if purity is the cause. IIRC, "graphite" is made
artificially by heaping ground charcoal or coke, lampblack, other junk and
pitch together into an electric furnace. The pitch decomposes to either
amorphous or graphitic carbon, binding together the mass; the other material
is recrystallized by the intense temperature, forming a polycrystalline
block. I've heard the structure described as nodules, globs, flakes and
other junk. It's still graphite, but it's kinda random I guess, and that's
why it's abrasive.

O.K.

I imagine natural graphite (probably damned expensive) would be wonderful
stock to machine.

I suspect so.

I don't know what metals are a proper choice for glass molds,
but it would have to be something which could run at a temperature near
that of the molten glass, so you don't get a sudden cooling and
fracture your workpiece.

Eh- pressed glass is made in warm (dark red heat, probably 1200°F) cast iron
molds. Worked glass is formed with steel and moistened wood tools!
(Lichtenfrost effect, anyone?)

You mean floating the glass above the wood on a film of steam?

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 17 Apr 2005 20:32:37 -0400, (DoN. Nichols)
wrote:



You're right. One of the problems of having to put on glasses
to read the small type in the _Handbook_, and having to take them off to
see the screen at about 24" distance from my eyes.

My Optometrist set me up with a set of glasses recommended for data
entry people.They are basically upside down bi-focals with the small
mid range lenses in the upper portion. It took me a couple weeks to
get used to them, but they work great for me and I even use them when
reading in bed.
Gerry :-)}
London, Canada

In article ,
Gerald Miller wrote:
On 17 Apr 2005 20:32:37 -0400, (DoN. Nichols)
wrote:



You're right. One of the problems of having to put on glasses
to read the small type in the _Handbook_, and having to take them off to
see the screen at about 24" distance from my eyes.

My Optometrist set me up with a set of glasses recommended for data
entry people.They are basically upside down bi-focals with the small
mid range lenses in the upper portion. It took me a couple weeks to
get used to them, but they work great for me and I even use them when
reading in bed.

Well -- I've got bifocals, too -- but I work with the screen far
enough away so I don't need the glasses for that. The close work inset
is on the bottom, for detail work, and the main parts are tuned for the
distance to my lathe chuck while standing. They *are* true safety
glasses, for this very reason.

But you know -- back when that book was new (1961), the type was
a *lot* larger than it is now. :-)

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

The binder would probably have to be clay or refractory. I just had an idea.
What about ceramic shell molds modified to do what you want? They probably
would have to be heated.
Karl

"Rodney" wrote in message
ups.com...
6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.

*Pour* it? Graphite is a crystalline form of carbon.
According
to my old copy of the _Handbook of Chemistry and Physics_, carbon's
melting point is 1350 C, and it *sublimes* (that is goes straight from
solid to vapor form) above 1300 C, so if you were to melt it to pour


Don
I don't want to melt it to pour.I am thinking in a cold cast way
Graphite powder mixed with polyurthane,epoxie, or some other type of
binder.
So I would beable to cast the mix have it set up and be able to blow
glass in it.
Snip:
In which case, you should probably tone back part of your .sig
for a while -- the part which reads:
Master Mold Maker
:-)
It took me a lot years to get that title.As well it only relates to
ceramic molds for ceramic castings,Silicone for resin castings and
latex for plaster castings.But you may have a very good point.
thanks
Rodney

http://www.weartech.com.au is an Australian foundry that has developed a
specialised high temperature steel for glass molds.

Drop them an email and see if they can help in your application.

Hope this helps,
Peter

wrote in message
ups.com...
Dear Sirs
Hi I am looking for some info on glass molds for blowing.
I work for a large Lamp Co in Miami Fl one of our dept is a glass
blowing and slumping.Myself I only know a little about glass as my
background is mold making ceramic, silicone and the like. Even thou I
helped set up the glass dept and build the glass tanks and use to
charge the glass at night before leaving that is about as far as my
knowledge goes. When we first started to do glass we were melting
marbles in side our ceramic kilns. I was making the one use waste molds
for the glass out of plaster EPK and vermiculite some one found the mix
in a glass book. That guy is long gone and I don't have the formula
any more it has been like 9 years since we needed molds like that. The
glass dept moved on to machined Graphite molds and metal molds. So my
hands have been out of the glass for around 6 years.
Do you have any idea were I can find the formula? (plaster EPK and
vermiculite mix) Book web site or do you know of it and can please you
share it.

Next they are looking at the cost of the metal molds we have to have
made 2 to 3 thousands dollars each and they are looking to find a cheep
way to make the molds so I was ask to look for fast easy ways to make
the molds. I have some ideas and I am wondering if they will work or if
you or any one you know has tried them. All the ideas relate to glass
blowing molds. All molds will be from 1 to 4 parts.

1.Ceramic molds like used in slumping the mold will be in 3 to 4 parts.
Because of undercuts.
2.Refractory like ZerCar can it be molded and will it last for say 50
blows.
3.Plaster EPK vermiculite mold.
4.Polyurethane mixed with metal powder
5.Epoxy mixed with metal powder
6.Graphite molds is there a way for me to make mold using it. I Would
like able to pour it.
7.Do you have any ideas that may be of help.


Thank You
Rodney Rock
Master Mold Maker / Design
Fine Art Lamps
Miami Lakes Florida
Phone 305-821-1055 EX 3065
Work Email
Home Email
Web Address www.fineartlamps.com

"DoN. Nichols" wrote in message
...
I mentioned the problem of it subliming below the melting point.
And, it looks as though you used one of the extended ASCII characters
for degrees, which displays as '\260' on my screen -- one reason for
avoiding using *any* extended ASCII character -- not everybody sees them
the same.

Yeah, but you're using that weird Unix thing that nobody else ever uses.
BG

AFAIK, most any windows or Linux reader displays ALT+0248 at the degree
symbol, so I'm reaching most of my audience properly, and you, the minority,
must cope. :-p

And we still have a disagreement of melting points (though not
as extreme as before).

Yeah, as I was typing I thought 7,000 seemed a bit hot... I always heard it
in the middle 6k range.

Forgive me for the use of HTML tags in there, but I was not sure
of any way to show italics to everyone -- some newsreaders may actually
*display* that as italics -- the rest will cue the reader that they
should be italics.

- Since your post is in plain text format, OE doesn't even try to translate
any HTML, and it gets as ugly as my use of an extended character.

So -- what is the source for *your* figures, now that I have
corrected mine?

Flinn Scientific periodic table, has various data alongside each element. I
might've screwed something up, since it lists temperatures in kelvin, but I
think I subtraced 273 properly, so *shrug*...
FWIW, it says 4188K melting point, which should be 3915C = 7079F - go
figure.
It quotes, for instance, Al M.P. correctly at 933K = 660C = 1220F, dunno if
others might be screwed up.

Yep -- sometimes achieved by surrounding the carbon with steel
which shrinks in the chilling, generating the forces necessary -- but
only for very small diamonds.

I thought the iron was only necessary as a catalyst, by dissolving it at a
lower temperature? High pressure cast iron, anyone?

Eh- pressed glass is made in warm (dark red heat, probably 1200°F) cast
iron
molds. Worked glass is formed with steel and moistened wood tools!
(Lichtenfrost effect, anyone?)

You mean floating the glass above the wood on a film of steam?

Well, come to think of it, the tools have to apply some force, so I'd guess
the heat of vaporization is used instead. That way, only a few thou's of
the surface gets charred, rather than a quarter inch deep and cracked. Less
smoke too, though more steam and cooling.

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

In article ,
Tim Williams wrote:
"DoN. Nichols" wrote in message
...
I mentioned the problem of it subliming below the melting point.
And, it looks as though you used one of the extended ASCII characters
for degrees, which displays as '\260' on my screen -- one reason for
avoiding using *any* extended ASCII character -- not everybody sees them
the same.

Yeah, but you're using that weird Unix thing that nobody else ever uses.
BG

Now remember -- we've been through experiments before, and
differing systems show different characters, in part depending on what
characterset is selected. And while most recent systems have a choice
of charactersets (and I'm using iso8599-15), but there are still people
who don't have a choice.

AFAIK, most any windows or Linux reader displays ALT+0248 at the degree
symbol, so I'm reaching most of my audience properly, and you, the minority,
must cope. :-p

I'll bet that more people than you think will be scratching
their heads at whatever they see on their screens.

And we still have a disagreement of melting points (though not
as extreme as before).

Yeah, as I was typing I thought 7,000 seemed a bit hot... I always heard it
in the middle 6k range.

Forgive me for the use of HTML tags in there, but I was not sure
of any way to show italics to everyone -- some newsreaders may actually
*display* that as italics -- the rest will cue the reader that they
should be italics.

- Since your post is in plain text format, OE doesn't even try to translate
any HTML, and it gets as ugly as my use of an extended character.

Of course -- I was depending on *people* understanding what the
"i/i" pair meant -- especially since I also explained it immediately
following.

So -- what is the source for *your* figures, now that I have
corrected mine?

Flinn Scientific periodic table, has various data alongside each element. I
might've screwed something up, since it lists temperatures in kelvin, but I
think I subtraced 273 properly, so *shrug*...
FWIW, it says 4188K melting point, which should be 3915C = 7079F - go
figure.

Is that specific for graphite, or general for carbon? Mine was
general, with no separate figures given for graphite, so that might be
the difference.

It quotes, for instance, Al M.P. correctly at 933K = 660C = 1220F, dunno if
others might be screwed up.

Yep -- sometimes achieved by surrounding the carbon with steel
which shrinks in the chilling, generating the forces necessary -- but
only for very small diamonds.

I thought the iron was only necessary as a catalyst, by dissolving it at a
lower temperature? High pressure cast iron, anyone?

I think that the shrinkage of the iron helps in the formation --
perhaps just that slight extra boost over what they could get from their
hydraulics.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---