Bob: Casting Director

The staff here at Belle Mead Hot Glass was on a hunt for a mold. Specifically, a mold for a dreidel. We use these molds to blow some of the classic ornament figures like the snowmen…

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
Hand Blown and painted glass ornament made here at Belle Mead Hot Glass
Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
Hand blown and then painted in. From a mold made here in the shop at Belle Mead Hot Glass

Unfortunately, the only one we’d been able to find was an antique German one from the 1800’s.  It was very expensive, very old and in Germany.  Luckily for us, Bob not only likes to build things, but he shows us how to build things too.  Casting in bronze is not only pretty amazing to work on, but also amazing to see, so we took some pictures to show you how its done…

 

 

 

 

 

 

The first part of the process was shaping a model dreidel.  We did this with a block of plaster of paris.  It was just the same size and shape as the glass ones we make now.  I didn’t take a picture of this because I didn’t know how destroyed it would get in the process…

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
these are the resin parts cast from the plaster model that will eventually become the bronze mold we use here at the shop.

 The plaster mold was split into two pieces from top to bottom and then cast in resin.  The resin is very sturdy and will stand up to the abuse we’ll put it through during the casting process. And now we have a very sturdy reverse of the glass shape we want to end up with.

We use two-part molds for this type of process.  They’re hinged and can swing shut.  As the gaffer hangs a bubble off the end of the pipe, another person traps the bubble in the mold.  The gaffer blows the bubble up to fill the void and take on the shape of the mold.

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
This is a selection of the molds in the shop. See the dreidel in the corner.

 

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
Bob has labeled the parts of the mold

We cast the bronze in sand that is packed into a wooden box.  The box and sand with the shape inside is called a “casting flask” The sand we use is mixed with a few other ingredients and is known as “green clay” or “Delft clay”.  The added ingredients make the clay stick together well so that it will hold the shape of the reverse of the mold.

 

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
Bob works on the mold parts in the hotshop.

Bob carefully packed the sand around the resin dreidel shapes. The sand is packed very hard – it is packed incredibly tightly, as in – it took specially modified power tools and a whole lot of time to get it ready. Then he very carefully lifted the resin pieces out.  Now the casting flask is ready for the bronze.

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
Here is the cope all ready to go – I think it looks happy. See how the drag has been packed with sand too?

In this picture you can see the Sprue, where the bronze will be poured into the mold and the runners that the molten metal will travel down as it fills the hollow.  The risers are the holes in the drag that will allow any steam or overflow to escape safely.

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
This little crucible is ready to go into the reheat oven

This is a little crucible with a few chunks of scrap bronze in it.  normally this would be heated inside of a casting furnace.  We don’t have one, but we do have a giant re-heat oven.  So, for this project we used that instead.

Belle Mead Hot Glass 884 Route 206 Hillsborough, NJ 08844 www.bellemeadhotglass@gmail.com 908.281.5516
The bronze we will be casting melts down in the little crucible inside our giant re-heat oven.

 

 

 

 

 

 

 

Making this mold was definitely a learning experience.  One of the things we learned was that Bob needs a furnace for more casting.

And so…