Make invisible ink at home!

How to make an invisible ink message

Make your own in­vis­i­ble ink!

Safe­ty pre­cau­tions

Wear pro­tec­tive gloves, eye­wear, and a mask. Per­form this ex­per­i­ment in a well-ven­ti­lat­ed area.

Reagents and equip­ment

  • 5 mL 1M cop­per(II) sul­fate so­lu­tion;
  • 2 mL 10% am­mo­nia so­lu­tion;
  • a cot­ton swab;
  • a Petri dish;
  • a plas­tic cup;
  • a piece of white pa­per.

Step-by-step in­struc­tions

Use the cot­ton swab to write a mes­sage on the piece of pa­per with the 1M cop­per(II) sul­fate so­lu­tion. No­tice that the mes­sage dis­ap­pears as it dries. To re­veal the mes­sage, put a few drops of 10% am­mo­nia so­lu­tion into the Petri dish and set the pa­per over the Petri dish. The mes­sage should ap­pear with­in 5 min­utes.

Process de­scrip­tion

Since the cop­per(II) sul­fate so­lu­tion is light blue, it dis­ap­pears as it dries. When ex­posed to am­mo­nia va­pors, cop­per(II) ions re­act with the am­mo­nia to form a dark-blue com­plex.