To cut the tubing:

Place the tubing flat on the lab table, holding firmly with one hand. Press your finger on the flat side of a triangle file and push the file FORWARD, making a scratch with the pointed edge of the file where the tube is to be broken. Press hard, but not hard enough to break the glass. You should hear the file cut the surface, leaving a white mark.

Turn the tube so the scratch is away from you, place your thumbs directly opposite the scratch, and push them QUICKLY through the tubing. The tubing should break cleanly and easily.

	The edges of cut tubing are sharp and can cut skin. Never use glass tubing that is not fire polished in an apparatus.

 

To fire polish the cut ends:

Flame polish by holding at a 45 degree angle and rotating the cut end of the tubing at the top of the inner bunsen flame until the flame colors yellow (showing the tubing is hot) and the end is observed to become slightly rounded. The glass will melt at the hot end and flow, rounding and smoothing the cut end.

 

	Heated glass stays hot for a long time! DO NOT touch glass tubing for 10 minutes after heating.
	Always place hot glass tubing on a heatproof surface to cool before using. Your lab table IS heatproof.
	NEVER allow water to touch hot glass tubing!

 

To bend glass tubing:

To bend glass tubing effectively you need an attachment for the top of the bunsen burner, known as a "flame spreader". The spreader produces a long, flat flame rather than a narrow, tubular one to bend glass. The flame spreader spreads out the flame enabling one to heat the tubing over several centimeters, instead of just at one place. This is necessary to get a smooth bend, rather than a kink in the tubing!

	It is possible to bend glass tubing without a flame spreader. You must move the tubing farther to the left and right (quickly), to heat the "bending area" (about 2 inches) evenly.

Heat the glass tubing with its length in the flame, rotating it back and forwards in the flame. Wait until it gets hot (note the yellow flame!) and just begins to sag.

Don't overheat the tubing or the walls will collapse.

Remove the tube from the flame and bend the tube upwards (against gravity) in a smooth motion, to get a bend of the required angle.

Bending upwards counteracts the tendency of the glass to sag under gravity and gives you more control, producing a smoother bend.

When you bend the tubing the two ends must be in the same plane, otherwise you will get a 'dog-leg' bend. A good bend is in one plane (so it will sit flat on the lab table), and the bend is smooth without any kinks or constrictions in the glass.

 

Sample bends:

is a good, smooth bend.   is a poor bend and was due to holding the tube too low in the flame so that the middle portion didn't get hot enough, and the tube only softened and bent at two points.   is a poor bend and was produced by heating only one small portion of the tube, for example using an ordinary bunsen flame, so the glass softened and bent at one, narrow point.

 

It is to recover a bad bend by reheating the glass and bending it carefully back into shape and providing the glass isn't constricted (narrowed by overheating). The "reworked" bend might not be pretty, but it will still work!

	If the tubing is kinked (as in sample c above) it is unsafe to use because the glass is stressed and the kink is a weak point. It may crack at that point, particularly if stressed mechanically or by heat. A constriction in the tube will not allow the gas to escape quickly and may lead to a pressure build-up in the preparation flask.