Supporting practical science, D&T and art
- in schools and colleges
Spirit burner
1.5mm (approx)
diameter air hole
Cotton string wick
Small jam jar
Materials
Small jam jar eg 1.5oz www.freemanharding.co.uk
6mm medium wall borosilicate glass tubing
6mm medium wall
borosilicate glass
tubing
Cotton string
Glue to secure tubing in place
Method
Cut a length of approximately 50 mm 6mm medium-wall borosilicate glass tubing
and flame polish both ends:
o Place tubing on a bench mat
o With one bold stroke and using the whole length of a 3 square file, make a mark on
the tubing where the cut is needed (you should be able to hear the grinding of glass
and see the mark).
o Wet the mark and turn the tubing so the mark is pointing away from the body.
o Pull the tube apart while at the same time exerting slight pressure behind the mark
with the thumbs (the tubing should break easily DO NOT ATTEMPT TO FORCE IT).
o Remove any jagged edges by rubbing the end of the tubing with a tripod gauze.
o Place the end of the tubing in a roaring Bunsen flame so it is just above the blue
cone, rotate and keep it there until it just melts (this is called flame polishing).
o Flame polish the other end.
Drill a hole in the middle of the jar lid big enough to take the glass tube.
Drill a small air hole to one side of the main hole.
Neaten the edge of the larger hole with a small file.
Insert the glass tubing into the hole and glue in place (hot glue gun works well).
Insert string wick.
CLEAPSS, The Gardiner Building, Brunel Science Park, Uxbridge, UB8 3PQ. Tel. 01895 251496 www.cleapss.org.uk