A pale orange solution is sprayed onto a sheet of seemingly blank, white paper.  Dark red and blue lettering appears.


Fe3+ + SCN- → FeNCS2+ (dark red)
Fe3+ + Fe(CN)64- → Fe2(CN)6-(s)

To Conduct Demonstration

  1. Spray dilute, acidic Fe(NO3)3 solution onto paper that has been painted with dilute KSCN and K4Fe(CN)6 solutions and allow to dry.

Demo Time: ~10 minutes


Eye protection should be worn to prevent spray from getting in eyes. 


Margaret Asirvatham, Spring 1995
Lora Ruffin and Michael Polk, Summer 2009