Author Topic: Owl and skull paperweights: how were they made?  (Read 1753 times)

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Offline Wuff

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Owl and skull paperweights: how were they made?
« on: April 10, 2011, 07:10:02 AM »
This Owl paperweight is on auction at ebay right now (images with seller's permission): upon enquiry the seller confirmed that a dent could be felt through the felt, i.e. an opening to a cavity. How was this cavity created? My interest in this weight arouse from a similar paperweight in my collection - due to the number of images allowed per posting I will post my images in the next post.
Wolf Seelentag, St.Gallen
Interested in any aspect of Scottish glass? Have a look at Scotland's Glass.


Offline Wuff

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Re: Owl and skull paperweights: how were they made?
« Reply #1 on: April 10, 2011, 07:21:12 AM »
So, here's my skull paperweight, based on computertomographic (CT) images of an actual human being. The last image was taken through the opening in the base. Base diameter is 90 mm, height 65 mm, and weight 696 g.

Which technique was used? The "lost wax technique" (or more general "investment casting") has been mentioned to me. Now checking books and the internet on these I understand how this works for outside shapes, or simple inside shapes (like some vases), where the cast can be pulled out. Just pulling out will obviously not work, however, for a structure like the skull, where glass would fill in sort of ducts within the cast.

I know from medical applications that 3D models can be built from 3D data sets (like CT images): is there some material for this, which is sufficiently heat resistant to be used as mold for glass - and then be dissolved chemically?
Wolf Seelentag, St.Gallen
Interested in any aspect of Scottish glass? Have a look at Scotland's Glass.


Offline chopin-liszt

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Re: Owl and skull paperweights: how were they made?
« Reply #2 on: April 10, 2011, 11:34:10 AM »
 :huh:
I thought that using the lost wax technique, the wax melts and runs out - but I can't quite see how in these fascinating bits - there doesn't seem to be anywhere for the melted wax to go, but I'm thinking about things from having watched bronze casting....
(I'm really not good at turning things around in my head - I always turn a map around to be in the correct direction for where I'm facing. It's a gender thing.)
You'd start with a model of the shape, then make a "negative" of it in plaster to include the final shape of the weight. Then you "cast" that from the negative in wax...... and now I'm afraid my fogged brain has refused to work out where we are, but I think it would work - there might be one stage more used for glass than for bronze......
Cheers, Sue (M)

“All things are subject to interpretation. Whichever interpretation prevails at a given time is a function of power and not truth.” Friedrich Nietzsche


Offline chopin-liszt

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Re: Owl and skull paperweights: how were they made?
« Reply #3 on: April 10, 2011, 12:51:53 PM »
 :hi:
Still tying my brain in knots, but I think what you need to end up with is an inflammable outer thing containing a solid wax effigy of the weight as it should be when finished, and a space to pour the hot glass into it, to melt and remove the wax. The inflammable outer thing is then chipped off to reveal the weight.
Cheers, Sue (M)

“All things are subject to interpretation. Whichever interpretation prevails at a given time is a function of power and not truth.” Friedrich Nietzsche


Offline Wuff

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Re: Owl and skull paperweights: how were they made?
« Reply #4 on: April 10, 2011, 12:59:29 PM »
There is a beautifully illustrated description of the lost wax technique to produce a Lalique whisky bottle - but only describing (unless I miss something) how to produce the bottle. The stopper looks somewhat similar to the two paperweights above - but I don't find a description how this is actually done.
Wolf Seelentag, St.Gallen
Interested in any aspect of Scottish glass? Have a look at Scotland's Glass.


Offline chopin-liszt

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Re: Owl and skull paperweights: how were they made?
« Reply #5 on: April 10, 2011, 04:37:30 PM »
Thanks very, very much for posting that link Wuff - fascinating!
(and the Macallan is, of course, completely worthy of the glass; the time, the trouble and the expense. :sc: )
Cheers, Sue (M)

“All things are subject to interpretation. Whichever interpretation prevails at a given time is a function of power and not truth.” Friedrich Nietzsche


Offline Wuff

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Re: Owl and skull paperweights: how were they made?
« Reply #6 on: April 11, 2011, 06:54:30 AM »
There is a beautifully illustrated description of the lost wax technique to produce a Lalique whisky bottle - but only describing (unless I miss something) how to produce the bottle. The stopper looks somewhat similar to the two paperweights above - but I don't find a description how this is actually done.
I was just informed by the site author that the building in the stopper was cut. Could the owl also have been cut? The structure looks much less complicated than the skull - I'll have a closer look when the owl arrives at its new home ;).
Wolf Seelentag, St.Gallen
Interested in any aspect of Scottish glass? Have a look at Scotland's Glass.


Offline Larry Thornhill

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Re: Owl and skull paperweights: how were they made?
« Reply #7 on: April 13, 2011, 01:34:00 PM »
It's very hard to tell from a picture, but I don't believe these paperweights were produced using a "lost wax" technique.  Generally, a lost wax process will yield a "positive" image when working with glass or metal.  These appear to be negative images.  I believe they were produced by reverse sand carving a solid glass blank.  That's only a guess though as I wasn't able to find any other examples on the web.

Regards, Larry


Offline Martyn K

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Re: Owl and skull paperweights: how were they made?
« Reply #8 on: April 13, 2011, 02:41:10 PM »
Could laser etching be a possibility? they're usually not hollow, but the detail on the skull reminds me of that a little.


Offline Wuff

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Re: Owl and skull paperweights: how were they made?
« Reply #9 on: April 30, 2011, 10:15:29 AM »
I was just informed by the site author that the building in the stopper was cut. Could the owl also have been cut? The structure looks much less complicated than the skull - I'll have a closer look when the owl arrives at its new home ;).
The owl has now been sitting on my desk for a while - but I'm still not sure about the production method. I feel it could well have been cut or by reverse sand carving (as suggested by Larry) - but not laser etched (too much material removed - which also applies to the skull).

I still have no clue about the skull, as the detail proves to me that the actual CT images were used for some sort of computerized production method. Any further comments welcome!
Wolf Seelentag, St.Gallen
Interested in any aspect of Scottish glass? Have a look at Scotland's Glass.

 

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