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.