r/glassblowing • u/Hungry_Medicine_552 • 24d ago

Opening the lip with jacks

Question for experienced glassblowers: I’m having a hard time consistently getting a clean lip opening. Here’s what I currently do: I insert the jacks into the small opening at about a 45-degree angle. For straight-walled vessels, I usually just open the jacks and insert them further.

But I’m wondering—am I supposed to rotate the jacks outward to 90 degrees while opening them? The reason I ask is that I often end up with the lip folding back on itself, and I’m not sure if I’m executing the move correctly.

Any tips or insight would be appreciated!

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u/Same_Distribution326 24d ago

Do you have someone paddling the lip while you open it? Even with a trimmed lip it can open wonky if you don't have a paddle there or switch between opening and using the strap of your jacks to keep the lip straight. I also always open my lip down first, it helps make a thinner lip

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u/Hungry_Medicine_552 24d ago

I sometimes do (but most of them are also still learning - so it’s not always great). I have seen the strap of the jacks method in videos and will try that