Topic: Quiz: A trial piece / blank - Which technique and who did it?

[chopin-liszt]

It's a gorgeous thing and I'm very, very jealous.   :thup:

[dirk.]

Thank you, Sue!  :kissy:
A short thought: All the ancient pieces seem to have an outurned rim. While the two other
methods won´t require the necessity for this, it´s an almost natural result of the
Wiedmann technique.

[Frank]

Is there no grey amongst this black and white or a space of doubt to be filled
with further thinking I wonder?

Not at all! Once a respected authority opinion becomes accepted opinion, it becomes historical fact. Touch that if you dare. I was roundly criticised before the Scottish glass conference for including a talk on Jacobite engraving, but this time it changed Scottish history receiving almost full acceptance.

Personally, I believe that the Lierke or the Wiedmann approach are the ones that the Romans are most likely to have used. Since 2005 we now have water-jet glass cutting technology which could produce cage cups with the greatest of ease. Could probably even include the tool marks if copying an existing piece   I guess if the Romans had used a second colour for creating the posts the solution would have been different.

You must be very pleased to have obtained this oddity and I am intrigued as to how you found it.

But is your piece made by casting or blowing and inverting to form the double walled vessel... followed by piercing and adding the pillar prunts? Now, how did Wiedmann do that, the principle of creating a double walled vessel can be seen in this post about flashing http://www.glassmessages.com/index.php/topic,1247.msg7855.html#msg7855  having then shaped his vessel he had to pierce it and insert the pillars, prunts. It is possible that this was done at the same time by piercing both envelopes and then adding the dark glass... yet the interior holes do not look like they were done that way. Also, how would he prevent the two walls from touching and fusing together as well at the same time maintaining vessel shape! So presumably the vessel was first cooled and the holes drilled, then coloured glass rod inserted with whole then being reheated to fuse everything together. Nightmarish complicated, moulding might have been easier. Look forward to hearing from you after you read the article. What is the article?

[rosieposie]

And here is the thread that brought the two camps face to face, well not quite...

http://www.glassmessages.com/index.php/topic,1015.0.html

Well I don't feel such a numpty after all....I did read this thread, but couldn't really relate it to the piece you were showing Dirk. 
I also looked up Cage Cups. but again, couldn't see how it was the same as what (to me) looked like a double walled glass cup covered in pointed prunts, even when you explained that they went through to the inner lining.  I could only see caged cups as being carved glass......Oh, I still have so much to learn......I hope I will eventually understand this technique, but at the moment it is making my brain hurt!!
I love these quizzes (quizzi?) they really make me think, and I always learn something.
Thank you Dirk.  :kissy:

[dirk.]

Sorry for not coming back earlier....
Like I said this is an unfinished piece, Rosie. So the outer layer of the vessel was meant to
be cut away to leave that lace-like pattern of a cage cup.
I had a phone call from the previous owner yesterday. Don´t want to be too mysterious...
It´s from the possession of Mr. Günther Hofmann, whose daughter was selling a few bits
and blobs on ebay. I contacted her after I had bought a few things and asked wether she
was absolutely sure about the origin - and so this wonderful connection turned up. Indeed
Mr. Hofmann is the last living of the Gralglas designers, so I need to gather a few questions
for his next call.
So the first hand information about this piece is the following: Karl Wiedmann was successful
with his attempts and several cups were indeed finished, but they turned out to be much less
elaborate than the old examples. In Mr. Hofmann´s opinion the cut from a solid blank theory
is still the most convincing for the making of the old examples.
But - we´ve left out the method of Kristian Klepsch, who makes his examples in the lost form
method, where the outer layer of his cage cups is applied around the earlier made inner vessel
by pate de verre.
Karl Wiedmann however tried this completely blown method. The clear bubble was inverted to
form this double-walled shape and cooled down to a certain temperature, where the inner
vessel was already stable enough to resist the following step. The prunts of hot glass are
applied and remelt the outer layer. Then a very thin piece of glass <1mm is stuck into the
prunt to form the connection between the two vessels and immediately pulled out again.
For the finishing the hollow form is filled with wax to make the thing stable enough for
cutting.
My copy of Karl Wiedmann ´Die Herstellung der römischen Diatretgläser´ has not arrived yet,
Frank, but it will surely add some further info.

[kitty-kat1234]

Please do not take this the wrong way,i am nothing but a lover of glass with no idea really!

When i first saw this piece i wondered if some-one had stuck those fairy stones on to it (sorry) :ooh:
I have just read through all the answers to your thread & have gone back to have another look at it by zooming in.

It is not until you see a piece like this & read through the tech etc to make this piece that you think
 "WOW,HOW TALENTED THESE PEOPLE ARE" IT IS TRUELY AN ART FORM!

As some-one said i am still trying to get my head around how it was made.

Thank-you kat

[dirk.]

Don´t worry, Kat. It wasn´t so different with me... When I first saw this piece, I simply
thought along the same lines: what a wonky, prunty, weird thingie.
But it was advertised as a Diatret trial piece and the name Wiedmann was mentioned plus
it really didn´t cost an awful lot, so I simply bought it. The reaL AHA-effect didn´t happen
before I could lay my hands on it.
And still - from the outside it may simply appear as a prunted beaker, but once you know
where and how to look at it, it reflects such a great creativity and skill.