glass balls

[hippieandrew]

ok, i was wondering if i were to make a hollow glass ball (like the ones for chinese fishing nets), would i leave the hole open and put in the kiln and finish the hole later? or close the hole then put in the kiln? if it is totally inclosed will the air pocket cause it to brake? same question on making air bubbles on purpose. is there a way to make a air bubble in a paper weight without it causeing stress? thanks a lot addicts

[darv]

I seal a lot of my christmas ornaments in the flame. They're fine once you get them sealed. sealing them is difficult though. If the flame hits them the vacuum causes the glass to suck into the ball where the flame hit. You have to cut off your point just right so it sucks in smooth with the ball but doesn't forme a divot. As far as air bubbles in paper weights, I've never had any trouble leaving large air pockets for visual effect. Just be sure to anneal them properly.

derek

[mountainflame]

I have had a few pieces crack because of the expanding/contracting air. The thicker the piece, the less likely that the air pressure can crack it.

[Mr. "Awesome!"]

I was doing sealed christmas ornaments for a bit, they are easy. I would just fume, blow a bubble, grab with claws and then make the loop while I'm cutting off the point. It will even suck in the tag part of the loop so it looks kinda slick when it's done. No breaks yet that I know of...

[Firekist]

the pressure from an airbubble shouldn't be enough to crack your glass.. unless your glass is thinner than a lightbulb. lighbulbs are under a vacuum.. and they're just fine.

bubbles aren't a big deal unless:
1 they don't have rounded edges (you can still have an air bubble with "shape" to it, but the edges can't be sharp.. look around for marbles with number air traps in them)

2 the air bubble is very close to the surface.. your glass will be fine, but if you drop it on that thin spot, the thin spot's gonna crack.

3 if your air bubble is so damn big that there's not enough glass on either side of the bubble, you'll have no strength in that area.. bubbles by welds are bad for this reason.

hope those points help.
z--seth