You will frequently be asked to place a glass tube, rod, or thermometer into a cork when working in a Chemistry laboratory. You must first poke a hole in the cork to do this. The goal of this tutorial is to teach you how to drill a hole in a cork and put a glass tube, glass rod, or glass thermometer into it. On completion of the experiment, your skill should include:

  • Bore a smooth hole of required size in a cork.
  • Insert a glass tube, glass rod, or thermometer into a cork
  • Remove the glass tube, rod, or thermometer from a cork

Material Required for Boring a Cork

A borer of proper size is used to bore a hole in the cork, insert a glass tube into the hole, and fit this configuration into the opening of a flask for distillation purposes or delivery of gases. In addition to cork and borer, one would require glass tube, water, NaOH, glycerol.

Experimental Procedure

Selecting a Cork

We need to choose a cork free of cracks and holes of proper size such that the small end fits one-fourth of the flask when squeezed gently.

Wetting the Cork

Wet the cork and push it on the cork presser as indicated. Lift the handle, then slide the cork into it before lowering it. The cork is going to be squeezed. To remove the cork, raise the handle one more. If you don't have access to a cork presser, the wetted cork can be rolled in a piece of cloth and slipped beneath the shoes.

Selection of Borer

Choose a borer with a diameter slightly smaller than the outer diameter of the glass tube to be installed.

Boring Hole in a Cork

  • As per the instruction, lay a rubber cork upon the surface with the tiny end facing upward (a).
  • With your left hand, hold the cork and place an appropriate borer soaked in NaOH solution in the spot where the hole will be drilled.
  • Rotate the borer while gently applying pressure to the cork while holding it upright.
  • To make the drilling smoother and faster, add a few drops of weak NaOH solution to the boring tube.
  • Boring the cork from both sides should be done such that the hole is vertical.

Putting the glass tube in the bore:

  • Using water, wet the cork.
  • Use water to wet the end of the tube that will be placed into the bore.
  • Using a handkerchief, hold the tube tightly with the right hand from the wetted end.
  • With your left hand, hold the cork.
  • Slowly rotate the tube into the bore, as indicated in Fig. 2.16. (a).
  • Dip the hole in the rubber stopper in caustic soda or glycerine to soften it, then insert the glass tube.


  • Choose a cork that is the right size.
  • There should be no fractures or holes in the cork.
  • Make circular markings on both sides of the cork, and the circular marks must be perfectly opposite each other.
  • Choose a borer that is somewhat smaller than the diameter of the hole.
  • Boring must be done from the top down.

Removing the Glass Tube

Simply reverse these methods to extract the glass tube or thermometer, i.e., place a greased bigger borer over the tube or thermometer. First, separate the tube or thermometer, then the borer from the cork. Remember, it's always preferable to waste a cork by clipping it than to battle to dislodge trapped glass.


In this tutorial we have learnt the following:

  • punched a neat hole in a rubber bung or cork.
  • put thermometer or glass tube into the cork hole.
  • Withdrew the thermometer or glass tube from the cork.


Q1. How would you soften the cork for boring a hole?

Ans: Cork hardens with time, and attempting to drill a hardened cork leads in the creation of cracks. To soften the cork, we must soak it in water. Press the cork in a cork presser, which is a mechanical device, after it has become flexible. We may also cover the wet cork in a piece of paper, lay it beneath our shoes, and press it. We would observe a cork that has softened.

Q2. What are the precautions to be ensured for boring a hole in the cork?

Ans: (i) Choose bores that are slightly smaller in diameter than the tube that will be placed into the hole.

(ii) Put a mark on the cork on both sides.

(iii) Drill one half of the hole from one side and the other half from the other side of the cork to get a uniform hole.

(iv) Due to the hardness of the rubber, the end of the tube to be inserted is normally dipped in glycerine or caustic soda solution before being placed.

Q3. How would you bore a cork?

Ans: (i) Arrange the cork with its thin end facing up on the flat surface or table.

(ii) Adjust the position of the borer on both sides of the cork to guarantee a straight hole.

(iii) When the cork is rubber, we use glycerine to lubricate the borer. Glycerine works as a lubricant on the hard rubber cork, which is why we do it.

(iv) Using your left hand to grip the cork securely and apply force, begin the drilling process by twisting it. Please ensure the borer stays vertical the entire time.

(v) Withdraw the borer and reverse the cork once half of the cork has been drilled. Begin boring from the opposite side until you get a hole.

(vi) The borer may now be removed.

Q4. How would you fit glass tube in the bore?

Ans: (i) Soak the ends of the cork that will be used to put the tube in water. Repeat with the end of the tube that will be utilised. This makes it simple to place the tube further into cork.

(ii) With one hand, hold the cork and the other, the tube.

(iii) Rotatively push the tube into the drilled hole of the cork while holding it near to the wet end.

Q5. What is used as a lubricant for cork?

Ans: One could use glycerine or caustic soda solution as a lubricant.


Simply Easy Learning

Updated on: 13-Oct-2022


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