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16.14.3 Insertion of Glass Tubes or Rods into Stoppers

The following practices will help prevent accidents:

  • Make sure the diameter of the tube or rod is compatible with the diameter of the hose or stopper. 
  • If not already fire polished, fire polish the end of the glass to be inserted; let it cool. 
  • Lubricate the glass. Water may be sufficient, but glycerol is a better lubricant. 
  • Wear heavy gloves or wrap layers of cloth around the glass and protect the other hand by holding the hose or stopper with a layered cloth pad. 
  • Hold the glass not more than 5 cm from the end to be inserted.
  • Insert the glass with a slight twisting motion, avoiding too much pressure and torque. 
  • When helpful, use a cork borer as a sleeve for insertion of glass tubes. 
  • If appropriate, substitute a piece of metal tubing for glass tubing. 
  • Remove stuck tubes by slitting the hose or stopper with a sharp knife.