Magic Inks

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Learners write their initials by applying different clear "magic ink" solutions to separate pieces of paper and then "develop" the inks with other clear solutions. One "magic ink" is a sodium hydroxide solution that is "developed" by phenolphthalein, an acid-base indicator. The writing can be made to "vanish" again using a hydrochloric acid solution. Another "magic ink" is a potassium thiocyanate solution that is "developed" by iron chloride, forming iron thiocyanate ions that appear red. Commercially available "Magic Pens" are also used to help learners understand how they work. For safety reasons, this activity works best as a demonstration for younger audiences.

Quick Guide

Preparation Time:
30 to 45 minutes

Learning Time:
Under 5 minutes

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 14 - adult

Resource Types:
Activity, Demonstration, Experiment/Lab Activity


Materials List (per group of students)

  • Five 100-ml plastic storage bottles
  • 5 large test tubes with rack
  • 5 one-hole stoppers
  • 5 non holed stoppers
  • cloth tipped swabs (keep 20 on hand)
  • 100 sheets of scrap paper, approximately 2 in. by 2 in.
  • Phenolphthalein (an indicator; keep 15 g on hand)
  • Five 250-ml plastic beakers
  • Sharpened pencils (keep four on hand)
  • Magic pens (CrayolaTM Secret Writers or GaltTM Magic Pens) (keep three on hand)
  • Colored developer pens (CrayolaTM Secret Writers or GaltTM Magic Pens) (keep eight on hand)
  • 95% C2H5OH (ethyl alcohol or ethanol) (keep 2 liters on hand)
  • FeCl3 (ferric chloride) (keep 25 g on hand)
  • KSCN (potassium thiocyanide) (keep 25 g on hand)
  • 1M HCl (hydrochloric acid) (keep 500 ml on hand) — OR — keep 500 ml concentrated (12.1M) HCl on hand
  • 1M NaOH (sodium hydroxide) (keep 500 ml on hand) — OR — keep 100 g solid NaOH on hand


  • Engineering and Technology
    • Engineering
      • Chemical Engineering
  • Physical Sciences
    • Chemistry
      • Chemical Reactions
      • Acids and Bases
      • Solutions

Informal Categories

  • Toys


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


Components that are part of this resource:

This resource is part of:

Access Rights:

  • Free access



Funding Source:

  • National Science Foundation