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Home Page --> Tutorial Lesson 11, Butt Seals


Tutorial Lesson 11, Butt Seals
Lesson 10
(Making a Test Tube)
Lesson 12
(T Seals)

Butt Seals

Butt Sealing is the process of joining two sections of glass tubing together - end to end. This exercise demonstrates the joining of two similar size tubes together. A variation of this seal would be the joining of two different diameter tubes as discussed in the T seal section of this tutorial. Two butt seal options are offered here. The first requires good rotational skills.

Option #1 - Rotation Method

  1. Cut two pieces of tubing into 8" - 12" lengths and fire polish the ends.

  2. Attach your blowhose assembly to one tube.

  3. Seal the second tube with a cork or use a test tube bottom from the previous lesson.

  4. Light your torch and adjust the flame.

  5. Rotate both ends of the glass tubing (as if fire polishing) in the flame. They should be close, but not yet touching.

  6. When the tube ends are red hot, remove both from the flame, stop rotating, and push the tubes together, making contact all around. If the tubes are not well aligned, you may need to start over.

  7. Place the sealed area back in the flame, concentrated directly on the seal, and then rotate and blow, maintaining ID and OD, to work the initial seam/line into one continuous piece of glass.

  8. Anneal. Remember, a glassblowing job is never complete until the glassware is annealed!

  9. Check your work - roll the final piece on a flat surface and ensure there is no wobble and that no section of the joined tubes ever leaves the ground.

Tip: Upon reaching Step 6 (pushing or "butting" the tubes together making a seal), some glassblowers will pull the tubes slightly apart immediately after butting them together. The reasoning is that when the tubes are butted together there will be a thickening of the glass wall at the point of contact. By slightly pulling the tubes apart the glass walls will come back to their original thickness, making it easier to work out the seal. Do not pull too hard, however. You want to avoid creating a thin spot or section in the tube, producing a potentially weak seal.

Option #2 - Stationary Method

Tutorial Lesson 11, Butt Seals
Lesson 10
(Making a Test Tube)
Lesson 12
(T Seals)


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