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Tips, Techniques, and Questions -- Technical questions or tips

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  #1  
Old 2013-04-09, 1:42pm
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Default Amazing but confused!

I watched a video on U Tube, Gianni Toso with Corning Museum of glass. He was createing a fairy, but I am totally confused, after picing up the fairy he added feet, laid her down worked on hands, picked her up and attached hands. Did not put it in a blanket or anything in between! He was working with morreti (Soft Glass). How is that possible?
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Old 2013-04-09, 2:15pm
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That's how the Italians work on their figural pieces. They work on one area and move on, and never let the old area back in the flame. Then the piece is annealed at the end of the day - kind of a "batch annealing" for a figure.
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Old 2013-04-09, 2:15pm
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I took a class with Loren stump - and he explained that the italians will leave a little 'spike' of glass where they want to return and join on new pieces. That way they can make a separate piece and join them together by heating just the small pieces of glass it works because they are thin enough to heat quickly without shocking. Like sticking a stringer straight into the flame will work but a thick rod would shatter.
Does that help? I'm not sure if I explained that very well.
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Old 2013-04-09, 2:16pm
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Do you have a link for the video? I'd love to see it
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Old 2013-04-09, 2:56pm
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I think if you go to you tube and serch for his name you will find it, the link address at the top just said you tube.
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Old 2013-04-09, 2:57pm
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That is what he was doing, it is so amazing! He does it with a small torch!
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  #7  
Old 2013-04-09, 2:59pm
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The corning video is at
http://www.youtube.com/watch?v=FYEQn...BBC08&index=16

If you want to understand this in detail then get this video from Artco Inc
http://www.artcoinc.com/lucio_bubacco.php
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Old 2013-04-09, 3:01pm
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you can find links to these on cmog web site.
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Old 2013-04-09, 3:04pm
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What's the link Mary Ann? I wanna see!

ETA. Duh. I need to refresh more often; off to check it out!

Alli
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Old 2013-04-09, 3:16pm
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Ok, still need to finish, but I have the same type of questions. How did her arm not pop off when he reintroduced it to the flame?!

Amazing.
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  #11  
Old 2013-04-09, 3:26pm
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There a couple of different techniques that these guys use together to be able to make these sculptures.

The one you'll see right away is that they progress from one end of piece to the other with out going back. What they are doing is gradually moving the heat down the piece so that they slowly cool the area that they just worked, easing it down past the strain point to reduce the stress in the glass.

The shockiness of the glass scales with the section, so the smaller the section the less likely it is to crack when reintroduced into the flame. You can see this principle when you stick a rod into the flame rapidly. The outside surface heats very quickly and expands while the interior is still cool. The resulting expansion mismatch causes the glass to explode. If you pull a stringer of one end of the rod and let it cool you can go back and introduce the rod back into the flame by starting to heat the stringer and working your way back to the larger section of the rod. If you take your time the heat will move up through the stringer slowly heating the glass as you move up the thin end to the rod.

Some of the items are garaged to keep them above the strain point so they can be gently reintroduced into the flame and connected with other parts that are also hot.

In the Lucio video he uses another technique where he uses the head of the figure as a heat sink to radiate heat out to a series of snake heads that he's making for the hair. By keeping the head hot he can keep going back to attach more snakes and at the same time the mass radiates heat out to the appendages to keep them from breaking if they get brushed by the heat as he's building nearby parts - and it also allows him to use bridging.

If you were using colors that are protected by a layer of clear you can flame out and flame back in a number of times before you would have to anneal. When you flame out you evenly heat the piece then slowly reduce the amount of oxygen in the flame until you have a pure propane flame. When carbon deposits on the glass you know that the piece is below the strain point. Likewise you can flame in on a cool piece. Starting with a propane flame you slowly heat the piece and then begin to reintroduce oxygen. When the carbon burns off the piece is above the strain point and you can work in a normal oxy/propane flame. The German montage artists use this technique to make vessels out of 104 Lauscha tubing. You can see that technique on this video http://www.youtube.com/watch?v=6OtXezwd3Go. When Thomas is done with the piece - he's done, no annealing is required.
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  #12  
Old 2013-04-09, 6:38pm
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great reply Talonst! thank you
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Old 2013-04-09, 7:08pm
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Sorry, I'm still confused. I understand your explanation Talonst, but it doesn't seem to apply to what I see in the video.

Prior to making the hands he was adding the feet to the fairy, so he was not working on the arms last. He then puts the fairy down for 5 minutes while he makes the hands; the fairy lays with the arms in the air, not on anything which retains heat. So the arms appear to me to be completely cooled, especially the way he handles the upper body as he is working on the feet. Also, The width of the arm he places the hand on is approx the width of the cane he used to make it, which seems to be...7-8 mm; it's not thin stringer. How does this not crack when he puts it back in the flame? I see he keeps his rods heated, but why not the fairy?

So confuzzled!

Alli
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Old 2013-04-10, 5:17am
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What's confusing is that he's working on 2 figures in the video. For the first 12 1/2 minutes he's making the hands and feet on an already completed figure that has been run through a complete annealing cycle and is completely cold. The annealing has removed all the stress from the glass so he can go back and reheat the thin appendage stubs at the feet and hands without fear of the glass cracking - he's a master too which doesn't hurt )
From there on the video shows him building a second figure. Each time he builds a section of the fairy he puts it in the propane fire "garage" on his right (left of the screen) where it is kept warm while he's working on the next section of the figure. He starts with the head and garages it while he's working on the torso and arms. He then takes the head out of the garage and fuses to the body and then garages the entire piece while he preps the wings and so on. You'll notice at the end of the video the figure has no hands or feet, that's because the entire piece needs to be completely annealed to remove the stress. You can see him put the figure on the wood paddle to put it into the kiln. After some number of hours in the kiln and after complete cooling he would then be able to make the hands and feet for this second figure.

Make sense?

BTW the use of the wooden paddle is interesting because it doesn't steal the heat from the piece like carbon would, so that's another way that you avoid cracking in soft glass. You'll often see them using wooden holders like clothespins instead of carbon or metal.

When I was at the International Flameworking Conference a few weeks back Vittorio Costantini did a soft glass sculptural demo where he used a bunsen burner running off to the side of his oxy propane torch (a midrange plus). When he was making a large sculptural element (in this case part of a sea horse) he would occasional bathe it in the heat of the bunsen burner. Since its only a propane flame it will not aggressively heat the glass like an oxy/propane flame will so is less likely to crack the glass. This brings the large section back up to temp evenly, similar to garaging, and then he could continue working in the oxy propane torch.

Did you notice that Gianni is using a national torch? Those are typically used for boro - kinda puts the theory that you can't work soft glass in a premix torch to rest. It's likely that he's using a lower than typical setting for his oxy regulator pressure - perhaps 5 psi - that's a guess though

Last edited by Talonst; 2013-04-10 at 9:24am.
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Old 2013-04-10, 6:49am
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I did watch the whole video and what Alli said is confusing me also. He works on the feet with the first fairy and set her down to create the hands, why did the feet not crack. I understand the fairy not being stressed and the small part of the arm or leg being reheated to attach feet and hands. After the feet being attached and laying down for several minutes is whats confusing.
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Old 2013-04-10, 7:11am
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When he's working on the feet he's starting with an annealed figurine -so there shouldn't be any stress in the piece to begin with. He heats the stub where the ankle will be and begins adding glass to make the ankle and the foot. He's always working away from the ankle towards the toes. He never reheats the previously worked area. Since he's always moving farther away from where he started the areas that he worked first are cooling slowly. Slow even heating and slow even cooling equal low stress in the glass. When he's done with the feet he puts the figure down and the glass continues to cool - presumably he's worked it in such a way that the thicker section at the ankle and through the top of the foot were essentially flame annealed - that is brought down below the strain point of the glass - before he stops working on them. There is still stress in the glass, but not enough to break it. Once he's done with the hands it goes back in the kiln to erase any remaining stress in the hands and feet and their connections to body.
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Old 2013-04-10, 7:54am
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Wow did not know that could be done!
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Old 2013-04-10, 9:40pm
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Quote:
Originally Posted by allicat View Post
Sorry, I'm still confused. I understand your explanation Talonst, but it doesn't seem to apply to what I see in the video.

Prior to making the hands he was adding the feet to the fairy, so he was not working on the arms last. He then puts the fairy down for 5 minutes while he makes the hands; the fairy lays with the arms in the air, not on anything which retains heat. So the arms appear to me to be completely cooled, especially the way he handles the upper body as he is working on the feet. Also, The width of the arm he places the hand on is approx the width of the cane he used to make it, which seems to be...7-8 mm; it's not thin stringer. How does this not crack when he puts it back in the flame? I see he keeps his rods heated, but why not the fairy?

So confuzzled!

Alli
Maybe I missed it somewhere, but maybe this is boro and not soft glass?? I played it with the sound off.

Edited: in the comments it says Effetre and he's using a "hushed" tip, but the reason I questioned it in the first place is because National torches are generally not used for soft glass. That would be quite a blast of heat.
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Old 2013-04-11, 4:24am
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Quote:
Originally Posted by Talonst View Post
What's confusing is that he's working on 2 figures in the video. For the first 12 1/2 minutes he's making the hands and feet on an already completed figure that has been run through a complete annealing cycle and is completely cold. The annealing has removed all the stress from the glass so he can go back and reheat the thin appendage stubs at the feet and hands without fear of the glass cracking - he's a master too which doesn't hurt )
Ok, I admit it. I'm thick.

I understood the construction sequence on the 2nd figure and how it kept the figure from cracking. It's that first one that still throws me. What you say makes perfect sense to me (annealed, thin appendage stubs, being a master LOL) except that's not what I see in the video in regards to the thin appendage stubs; I obviously don't know for sure if it's annealed just by looking! But, I do not see thin stubs for the arms or legs; they are the width of the rods to my amateur eye (and again, the rods for the trans blue has got to be 7-8 mm thick). In fact, he does pops them right into the flame to pull off some glass and the glass doesn't react.

I run a HH, which as we all know has a cooler flame than the dual torches. The way I interpret your explanation is I can anneal a thinnish piece of glass, let it cool and pop it into my flame without it exploding. Is that correct? I have reworked pieces that have gone blooey, but by bringing them slowly back up to temp; I've never tried annealing them and going back to them cold. Can I (knowing that I am about as far away from master as one can get and still have some experience melting glass!)?

I totally appreciate your extensive responses Talonst - thank you!

Alli
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Old 2013-04-11, 6:09am
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I don't think you're thick allicat, I just think you're seeing something that you're finding hard to believe because it doesn't mate up with your own experience.

The way to resolve this disconnect is to try out what you're seeing on your own torch. Trying to make a complete figurine, like what's in the video, from the start is just too complex and would likely lead to too much frustration. Since you're focused on the arm/hand joint why no try to work on that particular problem?

Break the problem down into it's simplest form by trying to make the arm and hand as separate pieces and then joining them together - the arm is just a tapered rod with a bend and the hand can just be a simple gather that you flatten into a lollipop with your mashers. Try to imagine the entire sequence of steps in your head before you're at the torch, then write them down and try them. Now practice it 5, 10, 50 times. Each time you'll learn something new and you can always come back to ask questions. Once you're successful, do it again but now make it twice the size. Once you've retired this set of problems then tackle the next set. Now make a torso with two arms and make the hands on each! In this manner you tackle small problems one at a time and then bring them together into more complex pieces.

Keep in mind the entire time that the shape of the glass, the colors you're using, the way you heat, handle and cool the glass all play into how it's stressed. What may not be working with one color might work fine with another. A particular bend or joint might always break while others never seem to. Making things over and over again is how you become familiar with the nature of glass in general, and the specifics of each individual color. Observing the patterns of what works and what doesn't is how you'll become skilled at making soft glass sculptures.

If you don't have them already I would suggested you pick up copies of Contemporary Lampworking Vol 1, and Kervin's Glass Beadmaking. Both provide detailed explanations of glass behavior, working principles, annealing cycles and so on.

If you can get to Corning NY, for a class Elijah Schwartz teaches a couple of weekend sculptural glass classes each spring and fall which focus entirely on soft glass - well worth the expense.

and here are some links for inspiration and to show what is possible with soft glass
http://www.vittoriocostantini.com/en/galleria.htm
http://www.luciobubacco.com/public/gallery.html
http://www.wesleyfleming.com/
http://www.cmog.org/bio/andr-gutgesell

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Old 2013-04-11, 6:21am
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Also wanted to add Kim Fields to that list. Her birds and the tree branches are made essentially as beads and then connected together using a brass pin - see it between the bird and tree branch? Her work is great and shows another approach to soft glass sculpture, which is to make a series of smaller pieces and assemble them together
http://www.northfiredesigns.com/Gall...ed_Roller.html
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Old 2013-04-11, 6:23am
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Quote:
Originally Posted by allicat View Post
Ok, I admit it. I'm thick.

I understood the construction sequence on the 2nd figure and how it kept the figure from cracking. It's that first one that still throws me. What you say makes perfect sense to me (annealed, thin appendage stubs, being a master LOL) except that's not what I see in the video in regards to the thin appendage stubs; I obviously don't know for sure if it's annealed just by looking! But, I do not see thin stubs for the arms or legs; they are the width of the rods to my amateur eye (and again, the rods for the trans blue has got to be 7-8 mm thick). In fact, he does pops them right into the flame to pull off some glass and the glass doesn't react.

I run a HH, which as we all know has a cooler flame than the dual torches. The way I interpret your explanation is I can anneal a thinnish piece of glass, let it cool and pop it into my flame without it exploding. Is that correct? I have reworked pieces that have gone blooey, but by bringing them slowly back up to temp; I've never tried annealing them and going back to them cold. Can I (knowing that I am about as far away from master as one can get and still have some experience melting glass!)?

I totally appreciate your extensive responses Talonst - thank you!

Alli
It is possible to work the stress out of the glass from one end to the other. I have always called this "stress chasing" (a family term). In other words you do not go back an forth heating and reheating. The figure is made from one end straight through to the other. You must know the steps in making your figurine very well to do this, there is not time for hesitation. If I take a piece of clear rod and heat it in the center and let it cool then examine it under a Polariscope, I will be able to see the stress in the glass. It is not where I have heated the glass but rather on either side of that area where the cool glass and hot glass meet. The wooden tools also help as stated. It is also very important to have the right fuel mixture as well. This can stop a lot of thermal shock to start with. I don't always do this type of thing, sometimes I use a hot plate that is above my torch and uses the heat from the torch to keep things hot for me.
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Old 2013-04-11, 8:20am
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The attached images illustrate hyperT's example.

The first picture here shows a section of glass tubing that has been spot heated and is being viewed under a polariscope to show the resulting stress lines.

The second image shows a series of pictures that illustrate what's happening. In #1 a section of rod is spot heated. In #2 you see a notional heat gradient, where the heat is concentrated on the gather that is being formed as the rod is heated and it's ends pushed together. Because glass is such a poor insulator the heat doesn't travel far from the gather. This sets up a very sharp temperature gradient over a very small distance. #3 shows the notional stress lines that form in the areas between the glass that's hot (in the center) and the glass that's relatively cold (at the edges). As the molten glass cools and begins to solidify the stress between the two regions get's "baked in". If you were to flash this with the flame again it would likely shatter. This drawing also shows that shape impacts the stress. Sharp edges or what's termed recurvate areas increase the stress in the glass dramatically, while soft curves relieve or distribute the stress. Finally, #4 shows that by expanding the temperature gradient over a larger area you can potentially reduce and spread out the stress.

Ultimately the kiln will remove the stress from the glass - but you have to keep in one piece up until that point

I try to visualize the flame as a paint brush. If I just put it on one spot on the glass it's like laying down a thick blob of color. What I want to do is fan it out so that the color fades out to a thin colored wash away from the area I'm working so that I keep the stress in the glass as low as possible.

BTW: This is exactly the same for Boro. You can get away with more initially, but it's still glass. If the pieces are large enough or there are sharp corners you run into exactly the same problems.

Hope this helps
Attached Images
  

Last edited by Talonst; 2013-04-11 at 8:26am.
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Old 2013-04-11, 8:58am
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Talonst and hyperT's thank you so much for all the info, sounds like it would be interesting to watch both of you work!
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Old 2013-04-11, 9:54am
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Quote:
Originally Posted by mz glitz View Post
Talonst and hyperT's thank you so much for all the info, sounds like it would be interesting to watch both of you work!
I don't work anymore I just have fun with glass LOL
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Old 2013-04-11, 9:59am
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Quote:
Originally Posted by Talonst View Post
The attached images illustrate hyperT's example.

The first picture here shows a section of glass tubing that has been spot heated and is being viewed under a polariscope to show the resulting stress lines.

The second image shows a series of pictures that illustrate what's happening. In #1 a section of rod is spot heated. In #2 you see a notional heat gradient, where the heat is concentrated on the gather that is being formed as the rod is heated and it's ends pushed together. Because glass is such a poor insulator the heat doesn't travel far from the gather. This sets up a very sharp temperature gradient over a very small distance. #3 shows the notional stress lines that form in the areas between the glass that's hot (in the center) and the glass that's relatively cold (at the edges). As the molten glass cools and begins to solidify the stress between the two regions get's "baked in". If you were to flash this with the flame again it would likely shatter. This drawing also shows that shape impacts the stress. Sharp edges or what's termed recurvate areas increase the stress in the glass dramatically, while soft curves relieve or distribute the stress. Finally, #4 shows that by expanding the temperature gradient over a larger area you can potentially reduce and spread out the stress.

Ultimately the kiln will remove the stress from the glass - but you have to keep in one piece up until that point

I try to visualize the flame as a paint brush. If I just put it on one spot on the glass it's like laying down a thick blob of color. What I want to do is fan it out so that the color fades out to a thin colored wash away from the area I'm working so that I keep the stress in the glass as low as possible.

BTW: This is exactly the same for Boro. You can get away with more initially, but it's still glass. If the pieces are large enough or there are sharp corners you run into exactly the same problems.

Hope this helps
Excellent example!
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Old 2013-04-11, 2:09pm
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Someday, I want to be able to say that!
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Old 2013-04-11, 2:09pm
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mz glitz mz glitz is offline
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Originally Posted by hyperT View Post
I don't work anymore I just have fun with glass LOL
To say This!
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Mary Ann
DAUGHTER OF THE KING!
Loving life and Lampworking

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  #29  
Old 2013-04-11, 6:34pm
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I hope you're ok with my fascination with your thread Mary Ann. And if you want to see HyperT in action, check out these threads:
http://www.lampworketc.com/forums/sh...d.php?t=240220
http://www.lampworketc.com/forums/sh...d.php?t=240304
And there is another somewhere as well!

I've started some basic sculptural which is probably why I'm so fascinated with this. Just this week I attempted (somewhat successfully!) Mary Lockwood's dragons, which requires a small number of pieces which must be made separately and then joined to the main piece (ears, tail, head, eyes). All the pieces required me to keep them hot before attaching - for example, I lost the first head (poor thing LOL) when I took too long trying get a good grip on the face so I could attach it by the neck, and it fell apart in the flame. Would I have had a better chance if I had annealed the head first?

And I have a rough understanding of the stresses inherent in worked glass (for example, I'm fascinated with the Prince Rupert drops; one of these days that's going to be one of my projects! Hrmmm, wonder if it can be done with soft glass). I also understand how proper annealing reduces these stresses. But you're right; because my limited experience has always been cool glass cracks when exposed to a certain level of temp, (ask me how many coffee pots I've exploded *sigh*) getting my head around the fact it's not always this way amazes me.

I'm on my iPad ATM, but when I get to my desk top I'll be perusing all those links. Thanx SO much Talon, Hyper!

Alli
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  #30  
Old 2013-04-12, 4:55am
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Quote:
Originally Posted by allicat View Post
I hope you're ok with my fascination with your thread Mary Ann. And if you want to see HyperT in action, check out these threads:
http://www.lampworketc.com/forums/sh...d.php?t=240220
http://www.lampworketc.com/forums/sh...d.php?t=240304
And there is another somewhere as well!

I've started some basic sculptural which is probably why I'm so fascinated with this. Just this week I attempted (somewhat successfully!) Mary Lockwood's dragons, which requires a small number of pieces which must be made separately and then joined to the main piece (ears, tail, head, eyes). All the pieces required me to keep them hot before attaching - for example, I lost the first head (poor thing LOL) when I took too long trying get a good grip on the face so I could attach it by the neck, and it fell apart in the flame. Would I have had a better chance if I had annealed the head first?

And I have a rough understanding of the stresses inherent in worked glass (for example, I'm fascinated with the Prince Rupert drops; one of these days that's going to be one of my projects! Hrmmm, wonder if it can be done with soft glass). I also understand how proper annealing reduces these stresses. But you're right; because my limited experience has always been cool glass cracks when exposed to a certain level of temp, (ask me how many coffee pots I've exploded *sigh*) getting my head around the fact it's not always this way amazes me.

I'm on my iPad ATM, but when I get to my desk top I'll be perusing all those links. Thanx SO much Talon, Hyper!

Alli
Prince Rupert's drops are more a novelty than anything else. Just make sure the droplet is completely cool before you remove it from the water or you can get a pretty violent explosion. This is true anytime you drop hot glass into water. We wouldn't want Prince Rupert's granules in your eye now would we?
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