How to Make a Test Tube #3

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Once the end is pliable, remove the glass from the flame while you swipe the glass tube across the end with the rod in several locations as you continue to rotate the tubing. The rotation will transform the end of the tube into a point. While you pull the rod away from the tube, the glass near the shoulder will become thinner as it is stretched. As soon as it starts to become hard (but not too hard), return the glass to the flame and continue heating on the (now thinner) shoulder of the glass tube If the glass becomes so hard that it no longer pulls, reheat carefully to maintain even heating around the end. Uneven heating here will lead to a lopsided end to the test tube.

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