problems with glass beads

ARE YOU ANNEALING??

if not - that is your problem.. not the wire.

STEEL is the best mandrel wire to use. Kaolin alone is not a good bead release....

sounds like you have multiple problems you need to resolve.

Cheryl DRAGON BEADS Flameworked beads and glass

How do you hold on to a copper wire that is in a flame? Ouch.

snipped-for-privacy@aol.combeads (Cheryl) wrote >

Have you disovered the ISGB message boards yet? By reading through old posts and asking your questions there you would be in contact with many experienced and new beadmakers and more quickly sort out your teething problems with torchwork.

I don't think that he was saying that the copper wire was breaking. I think it was the glass beads that were breaking.

You are right in that the glass needs to cool slowly to prevent the build up of stresses that will fracture it later.

You are a little off on the behavior of the copper wire.

Metals have basicly two states, hardened and annealed. All metals can be hardened to some degree and all can be annealed. Hardening typically happens one of two ways. The first is work hardening, where through mechanical stresses (bending, hammering, twisting, forming, etc) grains are pushed and wedged into each other and the metal gets harder. The increase in hardness is caused by the internal stresses in the metal itself. Over work the metal and it will fracture. The second method only works with iron (and a few others) based alloys that undergo a phase transformation at elevated temperatures. Steel for example, changes from one crystal structure to another a certain temperature. If you quench the steel you can freeze the crystal structure in a form that isn't supposed to exist at room temperature. The resuting stresses in the material make it harder. Curiously enough, some steel alloys can also spontaneously crack if they are fully hardened and not annealed after (just like glass).

If you take this hardened piece of steel and heat it back up to the transition temperature, some of the crystals start to revert back to the lower temperature form and the material looses some hardness, but gains ductility. This makes the material tougher, but I digress.

This same heating technique will anneal any metal. Work hardening stresses the grains by breaking them up and wedging them together, heating causes the grains to grow and relieve the internal stresses. If there is no phase change (Copper does not have one) the material can only be work hardened. Heating the metal up to its annealing temperature will anneal it and then it doesn't matter how fast you cool it, it is still annealed.

If the copper is breaking in this case, it is probably due to either oxidation or it is alloying with something in the coating or glass and getting intergranular corrosion.

If he got the copper from a welding store, then it probably isn't copper. It is probably copper clad steel. They usually don't weld with copper.

-- Joe

-- Joseph M. Krzeszewski Mechanical Engineering and stuff snipped-for-privacy@wpi.edu Jack of All Trades, Master of None... Yet

I make the beads under flame and then let them cool down at room temperature. I guess they cool down to quickly and brake then.

If this means if i have a place were i let the beads slowly cool down ... I let them cool down at room temperature. I would need a annealing oven then. I only have a small enamel oven. What temperature would be ok?

Sand is often used commercially. The glass has to be below its softening point before it goes in, though. We used to anneal marbles (made at about

240/min) by dropping them into 45-gallon oil drums and letting them cool down naturally when full. The runway and elevator from the marble machines had to be long enough to let the marbles cool down below the softening point before they entered the drums, otherwise they stuck together. The annealing was better than that obtained in a lehr.

"Normal sized" That depends on how small "normal" is, whether it has been flame annealed, and how well insulated you keep it. The biggest variable will be the thickness of the walls - thick walls require more annealing time. Big pieces that are blown thin will survive better than thick small pieces. If the marble is about 1/2" across, with a rather large mandrel, the wall thickness may be only 3/16". When a bead is more like an inch, the wall thickness may be nearly 1/2" and there will be much more glass as it will probably be longer. At some size, all beads should be annealed, not just soaked in vermiculite. Learning to do it early will save that first best big bead that otherwise might be lost, the effort wasted.

I would need a annealing oven then. I only have a small enamel oven. What temperature would be ok?>

I use an old converted enamel oven but you must be able to CONTROL THE TEMPERATURE And THE TIME OF COOLING.

sounds to me like all your beads are breaking because you are NOT annealing- it isn't your mandrels ... you HAVE to anneal...

Cheryl DRAGON BEADS Flameworked beads and glass

My mate who does some bead making just has a pot with an insulating media in it. I am not sure what it is, maybe vermiculite?. The bead once done is placed in the insulating media which slows the cooling to room temperature considerably compared to cooling in air.>

yeah - they do that in INDIA and CHINA too -- guess what - those beads ARE NOT ANNEALED.

guess what - they are FAMOUS for BREAKAGE

"slow cooling" is NOT NOT NOT annealing... there is NO SUBSTITUTE for annealing...

Cheryl DRAGON BEADS Flameworked beads and glass