Sending secret messages using cranberries

What interesting qualities are cranberries hiding?

Warn­ing! Only un­der adult su­per­vi­sion.


  • bak­ing soda so­lu­tion;
  • cot­ton swabs;
  • wa­ter­col­or pa­per;
  • cran­ber­ries or cran­ber­ry juice.

Step-by-step in­struc­tions

Soak a cot­ton swab in a bak­ing soda so­lu­tion and use it to write a se­cret mes­sage on some wa­ter­col­or pa­per. It can be “de­vel­oped” with cran­ber­ries – you just need to wipe the pa­per with some berries or cran­ber­ry juice!

Process de­scrip­tion

Cran­ber­ries are a great ad­di­tion to clas­sic Thanks­giv­ing dish­es – and you can al­ways sprin­kle them with pow­dered sug­ar! Cran­ber­ry juice and the berries them­selves con­tain nat­u­ral dyes known as an­tho­cyanins. Their struc­ture and col­or are high­ly de­pen­dent on the acid­i­ty of their en­vi­ron­ment. As it re­acts with wa­ter, bak­ing soda cre­ates an al­ka­line en­vi­ron­ment. As a re­sult, the ar­eas of the pa­per to which the so­lu­tion is ap­plied can change an­tho­cyanins’ col­or. This re­veals your se­cret mes­sage! If the mes­sage is faint, you can try dis­solv­ing bak­ing soda in boil­ing wa­ter. Such a so­lu­tion will be even more al­ka­line, and can also be used to write se­cret mes­sages when it cools. This is such an easy way to make Thanks­giv­ing 2021 even more fun!

Oth­er chem­i­cal spy hacks to amuse your chil­dren dur­ing your Thanks­giv­ing feast are in­clud­ed in the “Chem­istry for spies” set from the MEL Sci­ence sub­scrip­tion.