A pontil, also called a punty, is a solid iron or steel rod about 100-120 cm long that holds a vessel by its base after it is cracked off the blowpipe, so the open end can be reheated, shaped and finished. A small button of hot glass on its tip is pressed against the base to attach it, and a wet tool or a tap at the neck detaches it again. The attachment point leaves a rough punty mark that can be ground smooth or left on utilitarian ware.
Part of Glass Blowing and Forming
The solid rod used to hold a blown piece by its base during finishing.
The Pontil Gives Access To The End The Pipe Was Holding
While a piece is on the blowpipe, the end where the pipe joins is closed off. To finish a lip, that end has to be free, so the piece is moved to a second rod. The pontil is solid, not hollow, because nothing needs to be blown through it; its job is to hold weight and be rotated.
What You Need
- A solid iron or steel rod, 100-120 cm long per the corpus’s Glassblowing article.
- A small gather of hot glass (the button) on the tip.
- Jacks or a wet tool for the separation.
- A glory hole to keep the base hot while the transfer is made.
Method: Transfer From Pipe To Pontil
Step 1: Jack a neck. Squeeze a constriction where the piece will later separate from the blowpipe.
Step 2: Gather the button. Touch the preheated pontil tip to the furnace and take a small blob of glass.
Step 3: Attach. Press the button against the centre of the base, the end opposite the blowpipe. Rotate to keep the piece centred.
Step 4: Separate from the pipe. The glassblowing article says to apply a drop of water or a light tap with the jacks at the neck, and thermal shock cleanly parts the piece. The carrier states the same: crack the pipe off by touching a wet tool to the neck.
Step 5: Finish the open end. Reheat in the glory hole, widen with jacks, shape or fire-polish the rim.
Step 6: Remove from the pontil. Score the junction with a wet file or the edge of the jacks, then tap the rod. The carrier says the same, touch a wet tool to the attachment point and tap.
Step 7: Straight to the annealing oven. The carrier says unannealed glass cracks within hours.
Common Mistakes
- A button too large. The carrier calls for a small gather; a big join leaves a large scar and is harder to part cleanly. The corpus gives no button size.
- A cold pontil tip. Cold iron cracks the glass, exactly as with the blowpipe.
- Letting the piece sag. Keep rotating during the transfer; it has no support except the two rods.
Safety
Hot glass does not look hot
A pontil stub or a detached punty scar below about 600 °C shows no glow and still burns. Do not touch the broken scar or the tip to check them. A piece that drops off the pontil can shatter and throw hot fragments; keep the floor clear and wear eye protection.
What’s Next
- Learn next: Shaping and Finishing — what is done once the piece is on the pontil
- Combine with: Annealing Oven — where the finished piece goes