Molds for glassblowers

[mfoster]

I have been approached by a glass blower to see if I would turn some molds for him. The idea seems like fun and a bit of a challenge, but was wondering if anyone here has any experience with this. The glass blower says they usually like their molds done in wet fruitwoods. Finding a piece large enough may be a trick (he needs a mold to reproduce a glass lamp bell for Whoopi Goldberg). I would think that a large (12 at it's wideset) mold of fruitwood would be prone to checking and cracking. If anyone has experience with this I would be interested in talking with you, perhaps by phone.

Mike

 

[Richard Baker]

Mike,
Interesting about the "fruitwoods". Did he/she state a reason for that preference? Have always wondered about making one of those large scoop-looking tools that every glass blower seems to have. If turned wet and kept wet (like, in bucket of water) maybe the typical fruitwood checking and cracking is not a problem. Don't they always keep the "scoop" tool in a bucket of water?

Beautiful and amazing work on your website. Your "First Try" looks a lot like mine (Wood Mag article), but I like the shape of your better.

 

[george morris]

Web Site

Mike love your web site! Great work ! G

 

[Steve Worcester]

Mike,
Interesting about the "fruitwoods"....

Has to do with resins in the wood. Evidently fruitwood resins don't advesly effect the glass or glass sticking to the mold.

 

[DMcIvor]

Mike-

I have turned some molds for glass blowing. I used cherry, but also made one small mold out of maple (the last piece of cherry had too much rot, so I had to make a quick substitution).

The blower I made them for provided the green cherry log. He keeps his molds in buckets of water, so they stay saturated. From what I've seen, they appear to degrade from charring before they check or crack.

My mistake initially was in over-engineering the molds. I trade to keep the walls relatively thick, thinking it would increase the life span of the molds. The blower pointed out that the thick walls inhibit his ability to get his blowing rod (can't remember its proper name) properly positioned in the mold.

Don
mcivorwoodworks.com

 

[MichaelMouse]

Remember my tour at Waterford, and they used cherry for their tongs, paddles, molds and so forth. I doubt thickness matters a lot, since they are used wet, and the glass will "ride" on a cushion of steam. Why they don't char but slowly, especially if kept wet.

 

[Steve Worcester]

The blower pointed out that the thick walls inhibit his ability to get his blowing rod (can't remember its proper name) properly positioned in the mold.

Don
mcivorwoodworks.com

Punty is the name of the rod I think

 

[mfoster]

Thanks

Thanks all for the input. I'm a little out my depth with this one, but it may be easier than I thought. The glassblower sent me a couple of images of some molds he has, and I have been back in touch with him. From the pic I show, it looks like they try to keep walls relatively even in thickness, but pretty thick. Cherry may be the wood of choice for this project as the mold he wants needs to be shaped like a Hersheys kiss with the wide part being about 12" in diameter. Fruitwoods may be hard to find in that size. He said that he does not need it to be enclosed on the wide end, which will make turning it far easier.

Thanks Richard and George the comments on the website.

Mike

 

[Joe Greiner]

Probably stating something you already know, but I expect you'll get best results by constructing a two-part blank with well-matched contact surfaces, hinges pre-attached, and temporary (or permanent) outboard clamps for turning the inside. This should minimize seam lines in the glass products.

 

[MichaelMouse]

Probably stating something you already know, but I expect you'll get best results by constructing a two-part blank with well-matched contact surfaces, hinges pre-attached, and temporary (or permanent) outboard clamps for turning the inside. This should minimize seam lines in the glass products.

Glass blowers of the non-mechanical type swirl as they inflate the bubble, so it may not be as big a problem as with a machine-blowing mold.

 

[Joe Greiner]

Glass blowers of the non-mechanical type swirl as they inflate the bubble, so it may not be as big a problem as with a machine-blowing mold.

... until they stop swirling.

 

[john lucas]

I've only seen the 2 part molds used to form a more or less finished piece. The single part ladle is what all the glass blowers I know use to shape the bubble on the end of the blow pipe. It's used many times during the process of enlarging the vessel.
I may be wrong but I think Punty is what they call the glass they first put on the blow pipe to start the whole process.

 

[Joe Greiner]

My memory aid (Google) says "parison" is the blob before molding; also used for plastic pre-forms in machine blow-molding. And the same reports "punty" for the rod, aka "pontil."

 

[john lucas]

I talked to one of the glass blowers yesterday and she said the thing you are wanting to make is called a Block. She's going to see if they have instructions on how to make one.
The Punty is the solid steel bar that they charge with glass to transfer the blown piece from the blow pipe to this one.

 

[mfoster]

Thanks for the follow up John. I am expecting a visit from the glassblower here to discuss his needs and will let everyone know what I learn from that.

Mike