Little holes in blown ornaments?

[jenjeant]

Hi all,

I was wondering if someone could tell me why some people blow small holes in their blown ornaments before completely sealing them and why some people don't? My understanding is that the little hole is necessary so that the piece doesn't crack later.

I'm learning how to blow ornaments now and am just not sure whether that hole is necessary or not. It would be great to save a step!

Thanks!

[Cosmo]

The hole is just so it's easier to do. If you completely seal it, it's tricky to do. Try it and you'll see what I mean.

[lavendar420]

I make a little hole to let the air escape as it heats up. otherwise, after sealing the ornament completely, if the walls get soft the air will expand & push out a tumor if it heats up. I am by no means a master of this tho!

[menty666]

I usually don't put the hole in, but I like to live dangerously. However.....

There are two good reasons. 1) Because the air has a way to escape, there's less likelihood it could go boom in the kiln. Sealing it causes an instability in air pressure which could cause a problem as it cools. I know that because it's cooler in the kiln than it was in the flame the risk in the kiln is of it imploding, but still, heating the air inside of it makes me wonder.

2) If it's sealed, if you put the ornament back into the flame it'll start to implode, sucking the glass in and away from the flame.

[prairieson]

I've made ornaments in the hotshop and at the torch, in both cases sealed at some point before they go in the kiln. I've never had one im-, ex-, or in any other manner 'plode.

The sphere is a very stable and strong structure.