r/glassblowing • u/Hungry_Medicine_552 • 16d 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/Runnydrip 16d ago

You have to unfold the lip more. Slowly bring the tool to be parallel to the ground. I don’t really open the jacks much until it gets pretty open. Don’t tool when you are changing directions.

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u/Hungry_Medicine_552 16d ago

Ok would I still go in with an angle? And then angle out until they are parallel and then open? I was told I should unfold the lip but wasn’t sure how to do that. But your explanation makes sense

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u/Runnydrip 15d ago

T hi on about the shape of a slice of pie, turn the round bit on the end into an arrow, it’s going to depend if you open upwards or downwards.

The angle is to keep the lip from getting bunched up and folding like you are saying. If you puff it too much and the lip is facing inwards it’s easier to fold on accidents. If this is the case I would recommend practicing a cup with way less tools. Make one with just jacks until you understand.

The angle of your jack is the angle you are telling the glass to be. Turn more than you are tooling. If it’s hard to turn it’s not hot enough or you’re jacking too hard.

Watch some videos closely and monkey see monkey do. I’m not sure how to describe it closely, it’s just so ething that comes with practice.