Cracked male joint

[Neko]

i just had a joint crack right down the middle on this rig i was nearly finished with, ive never had this happen and iwas wondering a few things. what caused it? Is there a time window i have before i should get it back in the kiln to garage between assembly? i try to be as quick as possible and flash but think maybe i took too long adding an attachment and the joint end got too cool in my gong holder. second ,is there a way to fix it? i doubt it but its worth asking.. if i put it back in the flame is there a good chance of the crack growing? i wouldnt mind finishing it for a my own personal use. But im much more interested in figuring out how to prevent this fom happening again.

[yoloswag420]

Try annealing the joints before using but keeping temperatures the same between the glass and graphite is key. There was a thread a few weeks ago where the op said he fixed a crack without polishing the grind by putting a layer of soot beforehand.

[TlkQ]

Definetly anneal. Think about it, that joint is just a big ol' chunk of stressed out glass.

[Neko]

Ok anneal joints thanks! Any tips on keeping my graphite joint holder as hot as the joint?

[standard28]

Pop it back in kiln and bring temp over 1000 then take out and use a bushy flame hitting the outside and inside. Slowly increase oxy and focus more on crack. Keep most heat outside and flash inside till crack heals. Probably have to regrind a bit....

[Kaizen]

Tear the joint off and start over. It's a joint, they cost ~$1. Waste of time and gas trying to save ~$1.

[Neko]

No worries. Im really wondering how you guys keep ur gong holder hot. Do you let the flame touch it?or is it about only working it in the small window of time that tye graphite is hot for and then garaging agian?

[Colt]

Im curious as well... need tech help on this..

[harpentuan]

I am not curious of this topic at all.

[fUmEsNiFfEr]

Could you leave it in the kiln and fix it with your hand torch? This almost always works for me :chilling:

[JBob]

Iv learned nor to use the joint holder as much, I keep it warm with a plug on it in the kiln, I form my joint with a glass joint with wax, then use the joint holder to shape the bulb, then I weld a handle to the top of the dome and make attachments or sculpt whatever, then just use the joint holder again when opening the hole.

[harpentuan]

Fume, for you: 61010

[Aussie]

never had a problem with a joint cracking, never pre-anneal them, either, but it really depends on a few factors.
A couple of things to look at:
where's the joint from? I use german made joints and they're fine, chinese or indian joints may benefit from pre annealing
holders ... metal and graphite holders may not be particularly kind to the glass, they suck out heat and when heating up they expand at a different rate to the glass, so on expansion may exercise enough compression on the glass inserted into them to break the glass.
I don't use special holders to hold my joints. I pull a strong point (or on larger joints fuse on a smaller diameter tube) on the tube side of a male and female joint and those are my two holders. I put a single or double layer of paper around the female before I insert it into the male, which means i either wrap the joint or the holder, depending on which side is female. This has the benefit of preventing joint lock for two reasons. 1. the glass of the joint and the glass of the holder will ideally expand at the same rate when heating up and 2. the paper in the joint creates a cushioning buffer (even if it chars a little) between the holder and the joint. Remember to use gentle pressure when blowing after attaching the joint, as when using this method it is possible to pop the holder off the joint if being too heavy handed.
I always find it odd when people talk about tools like joint holders ... a lot of tools are totally unnecessary, considering that so many tools are right there in front of your nose ... the glass itself.
Hope that all makes sense.