Etching iron with iodine

Create a drawing on an iron plate using iodine solution

Difficulty:
Danger:
Duration:
40 minutes
Experiment's video preview
Chemical formula

Safety

  • Put protective eyewear on.
  • Conduct the experiment on the tray.
  • Keep a bowl of water nearby during the experiment.
  • Place the stove on the cork hot pot stand. Do not touch the burner after the experiment - wait until it cools down.
  • Put protective gloves on before step 6.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

FAQ and troubleshooting

Wax drained away from the iron plate. What to do?

If too much wax is melted, it starts draining away from the plate. Don’t worry, it will not ruin the experiment. The most important thing now is our wax blank for future drawing. Extinguish the candle, then take a pick and carefully cut away excessive sags of wax. Now you may easily remove the plate from the flame diffuser without damaging the wax layer.

I keep trying to scratch a drawing, but wax comes off in pieces.

Most probably, the layer of wax turned out too thick. Scratch away all the wax and deposit a new layer, but this time, don’t overdo it—the plate should be covered with an even, thin layer of wax.

The drawing hasn’t etched nicely. How to fix it?

There are several reasons for unsuccessful etching. It could be a thin layer of wax, which was left on the area with drawing. Then, this remained wax could have prohibited iodine from reacting with iron. Moreover, it could be that iodine hasn’t been distributed evenly over the plate. Finally, another reason of failure could be an exposure time of less than 20 minutes. Keep in mind these reasons when repeating the experiment.

Step-by-step instructions

  1. Place a candle into the solid fuel stove and light it.

  2. Cover the stove with the flame diffuser, then set on it an iron plate from the bag marked “Fe”. Wait 2 min.

  3. Take a piece of wax and carefully rub it into the iron plate. Warning! Metal parts of the setup are very hot!

  4. Extinguish the candle and let the stove cool down. Wait 5–10 min.

  5. With a pick, scratch a drawing on wax.

  6. Add 1 drop of liquid soap onto the metal plate.

  7. Now, add 5–10 drops of 2.5% iodine solution to the drop of liquid soap. Distribute this liquid evenly on the plate. Wait 20 min.

  8. Wash off iodine with water.

  9. Thoroughly clean all the wax off with a pick.

  10. You created an etched drawing on iron!

Graphical step-by-step instruction

Disposal

Dispose of solid waste together with household garbage. Pour solutions down the sink. Wash with an excess of water.

Scientific description

Why is it necessary to heat the plate?

For the experiment to be successful, it is important for the plate to be entirely covered by paraffin. To achieve this, paraffin is melted with the help of heat. As soon as the plate cools down, paraffin solidifies again and protects the plate from reaction with iodine, except for the area, where we have previously removed the paraffin by “drawing” our image.

Why does the image appear?

Being a typical metal, iron acts as a reductant – the substance, which gives the electrons away in red-ox reactions. Iodine, another participant of the experiment, is, on the contrary, a non-metal, that is why it tends to take the electrons in the reactions with electron exchange. Due to the paraffin and soap, iron and iodine get in contact only in the area of the image. Such a “meeting” is accompanied by a simple reaction:

Fe + I2 → FeI2

The obtained iron iodide is a water-soluble compound, which can be easily removed from the plate if we rinse it. Naturally, iron is slowly “spent” in the places, where we have removed the paraffin by “drawing” the image. It results in the formation of cavities, which stay on the plate even after all the paraffin is removed, giving our image.