Are rods and tubes annealed when we get them?

[Glassroots]

I am working on a project and will probably need to build a rather large kiln. I am wondering if the rods we use come pre annealed? Also where would I find the load bearing capacity of a certain diameter rod. These are for some installations I am trying to do, don't know if it will work or not.

[Greymatter Glass]

Define annealed, but probably not.

most manufacturers have physical data (white pages) on their websites.

[themoch]

load bearing would depend on the length of the rod you're using. if they do have any data, it would have to be converted. If i remember my physics correctly there's some sort of equation to figure this stuff out exponentially.

[Dom]

I would figure that yes they are annealed, otherwise I think they wouldnt even make it through transport.

[David Sandidge]

Excellent question. I don't know the answer to this, but as far as I'm aware, clear glass and tube from most manufacturers is extruded. It then runs down a conveyor at a specific speed while still in a molten state in order to determine the diameter. At the end of the conveyor, it is cut to length, then packaged. Unless there is an annealing process between the cutting and the packaging, I would guess that it's not annealed. I'm also guessing that the nature of the extrusion or "pull" if you will, doesn't create a lot of stress so it may not be needed. You could answer this question by viewing the glass through a polariscope which I have done and not noticed any visible stress.

As to the other question about load capacity, I have no clue.

[Mike_Aurelius]

I can tell you that the rods from simax are not annealed...I had one break weird on me awhile back and just for shits and giggles put it under a polariscope -- huge amounts of strain in the glass -- very reminiscent of induced stress from case hardening. It is my guess that as the extrusion is being done, the rod is being subjected to rapid cooling so that it does not lose its shape out of tolerance, rapidly chilling the outer skin to "freeze" it.

[Greymatter Glass]

The draw process I've seen sort of slow cools the glass. not a proper annealing, perhaps, but slow cooling none the less. I've looked at boro Artistic in a polariscope and it's fine. But seeing stress in a curved plane is _VERY_ difficult to analyze, so whatever.

-Doug

[Cosmo]

I'd have to believe that colored rods aren't annealed either. Think about colors like Triple Passion and Amber/Purple. If you put them in the kiln and anneal them, the will turn purple. But when you get the rods, they are yellow or amber.

Plus, when you are making glass on a big scale like that, you'd have to have a huge kiln to anneal all that glass in (or anneal it in smaller batches), and that would also add a lot more time to the production process.

[colonel4bin]

They have burners on the sides that slow cool the glass as it runs down the rollers after being extruded, I went on a tour of a schott boro factory once and asked that question, that's what they showed me!

[mer]

yesterday i scored a piece of chinese color tube and went to snap it with my hands. it broke on an even line 4 inches from where my score was. to the best of my knowledge that would suggest stress in the tube. i can only assume that chinese glass is not properly annealed.

[Glassroots]

They have burners on the sides that slow cool the glass as it runs down the rollers after being extruded, I went on a tour of a schott boro factory once and asked that question, that's what they showed me!

I am using schott for the project so I guess I am in the clear, literally!

Thanks for the suggestions

[Frankie Hess]

yesterday i scored a piece of chinese color tube and went to snap it with my hands. it broke on an even line 4 inches from where my score was. to the best of my knowledge that would suggest stress in the tube. i can only assume that chinese glass is not properly annealed.

I'm with you on this one, I use chinese tubing and if I introduce it to fast it exlodes all over my bench. I love it to, it adds a little excitement!

[Greymatter Glass]

I'm with you on this one, I use chinese tubing and if I introduce it to fast it exlodes all over my bench. I love it to, it adds a little excitement!

If you want to step up to Schott Boro Artistic let me know. It won't blow up in the flame (as often - it happens to all glass from time to time)

-Doug

[Glassroots]

That would remove the excitement???