Why doesn't it crack?

[Bo Diddles]

I just don't get it. As far as I know, you can get away with acute angles only if they are tooled in and then heated. So what gives with this (http://www.glasspipes.org/Img156309_Saw_tooth_Spune_Img156309_DSC_.asp) awesome piece by salt?
There are acute angles everywhere, that afaict are there because the glass wasn't fully melted. I could never get away with this.
What am I missing? (other than years of experience & talent)

[Mecha]

Acute angles are not guaranteed to crack. They are just weak points that are likely to crack without much provocation, at least, that is how I understand it.

I had all sorts of my newb work survive for years with acute angles at the marble attachments.

Remember Jerome Baker tubes? half of those were literally covered in acute angles.

Salts work may just be so sick as to defy any perceived rule of thumb....

[p.j.]

the glass was molten when he did the work. he made the spoon part, then heated his rods to molten then heated the spoon and laid them on

[menty666]

I don't know, but that thing is simultaneously awesome and creepy. I kind of want a piece of his work just to skeeve people out when it's lying on the table :)

[The Lorax]

as long as you melt it in, then shape it to those sharp angles you should be fine... thats what i've noticed with my small amount of sculpting experience so far.

[Glass Grimoire]

Hmm this is actually quite a tricky subject, i would say learn to follow the rules first so that you can break them later. Basically Good connections are a must, anywhere that you have a bad connection you create a stress point, if you create more stress the liklyhood of cracking goes way up, not to mention that the connection is more likly to break all together. With that said come the exception. So With the Piece of salt's that was illistrated, all the conections are much cleaner that you gave them credit for, what you see as an acute angle i'm seeing as a cut angle. first he creates a perfect conection then he cuts his accute angles in. this give a differrent type of connection that is both fully bonded and higher in stress. In other words if you never get the initial connection worked in the stress leves for this peice could be to high for survival. It's the difference between a punty and a weld. With the punty the glass never fully flows together your left with two peices of glass that are stuck together, with the weld you end with one peice of glass.

As for why good artists use high stress connections, simply put sometimes there is no other way to acheive a certain look. Personally i have done a lot of floral sculpture, Nature unfortunatly does not follow the clean connection rule. If i want to be able to create certain types of looks or flowers some of the connections have to have acute angles in order to look real. This leaves the glass artist with a challange Asthetic vision, vs structural quality. The goal of this challenge is to have a balance between the two. Use acute angles only when the asthetics demand it, Always ensure that When you use acute angles you have also used a good connectio, Practice practice practice to learn the balance and you will be suprised at what you can really create.

[Bo Diddles]

Thanks for the responses everyone.
As I said, I do know that fully melting in the colour and then carving is one way to get an acute angle, and there are many examples of this on Salt's piece. What I don't understand is where it looks like the rod was just laid on. I don't see that it's possible to fully melt in an acute angle and then carve exactly along the line between the two colours to create that look.
Maybe this (http://www.glasspipes.org/Img156312_Saw_tooth_Spune_Img156312_DSC_.asp) is a better example. There is no way the eyelids were fully melted in and then carved.
If the rod were fully molten, I would expect a much thinner 'smear' than what is shown.
If anybody has received the latest glass alchemy poster, there are lots of places on the various goblin heads that are definitely not fully melted in.
I'm thinking at this point my best conclusion is this:
Lay the rod on hot, don't heat (quickly) that part ever again, and cross my fingers....

[VOORHEES]

Flame annealing (sp?) is a key factor.

[The Lorax]

those eyes could of certainly been fully melted then carved. done it myself, just don't have pics of the slide yet since ive been waiting for the sun... trick is to not melt it too quick and keep touching it up w/ your scultping tool to keep the defined edges.

[Robert Mickelsen]

The very term "acute angle" is really a simplification of the issue. The reason that "acute" angles break is because the heat cannot pass out of the glass without leaving stress at the join. Classic "acute" angles are that way because they were not fully welded together. But what you see on Salt's work is different. Those seams are welded completely and then cut or folded. What appears to be "acute" at first glance is actually rounded on a very small scale. The difference is subtle and takes time to fully understand. Salt is clearly a master.

[Johan]

I think it all depends on what glass(specifically what colors) your using. Some colors weld really easy and can take a lot of abuse while some others dont and will crack with slightes strain.

[matte eskuche]

when adding bits or assembling connections somewhere in piece, if you work in such a way as to leave the most stress in the connection and then just flame anneal and leave the piece on the bench, you can then sit back and watch how and where the piece cracks.

this will give you insight into how to approach the piece the next time with a better annealed connection while retaining a detailed aesthetic. if you repeat this approach every time you are working on a new design or thicker piece or thinner piece or more detailed piece, etc. you will be able to make tiny adjustments towards the balance of having detail and strength in the finished piece.

i say most of this because everywhere i go the kilns are turned on just after the lights and the music. throwing everything in the kiln completely takes away ones ability to learn what is happening due to what stress was left in the piece.

it may sound like a waste of glass or time or both, but working without the kiln and purposely breaking pieces to see where they will cleave can teach you tons about your connections and bits etc.

i have to disagree with Grimoire's first statement, break all the rules and push way past the edge of what you know you can get away with. pay close attention to cause and effect and make adjustments backwards towards strength when you have failure due to stress. at some point you will find a way to reach the furthest limits of detail within the piece while still addressing issues of strength and anneal.

[Bo Diddles]

^ Damn man, that's some great advice - I think you just told me exactly what I needed to hear...
thanks to everyone for their help, I feel like I learned something significant from this thread - another piece of the puzzle, if you will...

[The Lorax]

some great info there from RAM and Matte

[Swampy]

and an excellent question from diddles in the first place, good to see folks are not shy to ask up. good job.

[rustyglass]

I think Salt gets the credit for this quote too, but I think it applies..."there are no rules, there are only ideas and thermodynamics." Which I interperet as do what you want and the glass will either agree or disagree.

[FredLight]

Try dropping it once.

[FredLight]

It's great work, and if I had that piece, I would be super careful.

[Bo Diddles]

Ya, that's what I'm just starting to realize - you really do need to learn the 'rules' when you're starting out, but you only learn the real limits of what you can do by pushing way past these limits. Sometimes I'm a little timid, and I get to thinking that everything I make has to be a masterpiece, and I forget that I still have so much to learn, which equals lots of scrap glass. I keep telling myself that it's not wasted time though. Even spending four hours on a piece that eventually doesn't make it teaches me so much.
Enough blabbering - to the workshop I go!!

BTW - thanks again to everyone for the great responses. To have both Matte and RAM sacrifice some time to help me out makes me feel honored, or maybe not worthy, or something. Seriously, it's like learning guitar and being able to ask Slash for some pointers.
This forum rocks.