Glass blowing molds

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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
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

Re: Glass blowing molds
 Looking at your list, I have start with
 Are you blowing the molds per your title or in line 6, you say you want to
  What are you making?  Shades?  Parts?  How big.
  The plaster, EPK, vermiculite should be a very low use mold.  The EPK
would make it more clay like while the vermiculite is usually an insulator.
 Graphite is used for pour and press molds.
 Iron would give more multiple uses per mold but requires special
  Epoxy or polyurethane won't work, will burn.
  Because ceramic shrinks, you will have to work to scale - casting
oversized, shrink on drying and firing, but you probably know that.
Mike Firth
   Hot Glass Bits Furnace Working Website
We've slightly trimmed the long signature. Click to see the full one.
Re: Glass blowing molds
We are blowing glass. What thay are looking for a cheep way to make the
blowing  molds.As the metal molds we are using now are very costly. 99%
of our glass parts are brand new so  molds need to be made One type of
part is a small shade to very large 2' to 3' tall and very fat. this is
but one style at the link below.I will take some photos at work and
send them to you if that will help.
Thanks So Much
Rodney Rock

Re: Glass blowing molds
should have been.
What thay are looking for is a cheep way to make the glass blowing

Re: Glass blowing molds

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Why couldn't that particular mold be wooden?  Fruitwood?  2 part hinged mold
with an open top, be blown "upside down" from the picture.  I'm just
guessing, asking myself also.


Re: Glass blowing molds
Thay are looking for real  cheep mold alturnatives.

Re: Glass blowing molds

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Looking at that, I don't see why you don't try wet wood as a mould.
Two part and it drops down into a water bath between blows.
Terry Harper
URL: /

Re: Glass blowing molds
Molds for blowing do not have to be from steel, aluminum works fine. If your
looking for precision molds though you will have to have a mold  maker
familiar with the glass blowing process fabricate the model and then have
the blow mold cast. Nothing of quality comes cheap though. Obviously a 1
part mold is going to be a lot cheaper than say a 4 part mold. The company
your looking for is Steinert Industries in Kent, Ohio. . As far as waste molds are concerned you
can use 1:1 plaster/silica 200 mesh by weight. This type of waste mold has
been used since the 19 century. The formula your looking at is used for
bronze casting. Slump molds can be fabricated from most any type of clay and
then bisque fired. Keep in mind though you cannot make the clay excessively
thick. Clay slump molds are usually less than 1/2 thick. I would not
recommend blowing into Zircar as you really cannot put a great deal of
pressure into the blow because the Zircar is really not a rigid product.
Zircar is good for multiple castings if you do not have any undercuts.
Graphite is not bad for pour molds but cannot be used for casting that
requires you to put the graphite in the annealer and leave it there for the
extent of the annealing and cooling cycle. The graphite binder will
deteriorate and the mold will fall apart in short order. .

Re: Glass blowing molds
 Go with Henry's advice - he knows more about casting than any other 9
people likely to be on here.

Mike Firth
   Hot Glass Bits Furnace Working Website
We've slightly trimmed the long signature. Click to see the full one.
Re: Glass blowing molds
Wow you guys are really helpful this the kind of feed back I need I
will be getting the book Glassnotes.Thanks for all you reples please
keep them coming

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