How to Make Invisible Ink

Linda Casey Whistler Elementary School
11533 South Ada
Chicago IL 60643
(312) 535-5560


The students in grades four - six will learn how to make two types of invisible
ink and write a message with each type of ink. The students will write a paper
comparing and contrasting each type of ink.

Materials Needed:

Ink # 1 Ink # 2
Lemon Juice Corn Starch
Small glass Hot Plate
Toothpicks Toothpicks or Cotton Swab
Paper Pan
Electric Iron Iodine Solution
(1 teaspoon of iodine in 10 teaspoons of water)
Small Sponge

Activity #1
The teacher will introduce the experiment by asking "What are some ways to
write secret messages?". After the discussion, the teacher will demonstrate how
to make ink #1.
#1. Pour a little lemon juice in a glass.
#2. Soften the point of a toothpick in the juice.
#3. Write a message with the juice.
#4. Heat the message (with the iron) to make it visible. The message should
appear brown.

The students will be given materials to write messages and they will use the
iron to make their messages visible. The teacher will then pass out index cards
(each card will have the numbers 1, 2, 3, or 4 prewritten with ink #1 by
teacher). The students will make their numbers visible by using the iron to
heat them and break up into groups according to their numbers.

Activity #2
The groups will be assigned lab stations. Each station will include materials
for making ink #2. The hot plate will be set up at the teacher's station.

#1. Mix a small amount of water with cornstarch (use about 2 tablespoons of
cornstarch and 4 teaspoons of water) in the pan and stir until smooth.
#2. Heat the mixture for several minutes. Stir. (heat each mixture separately)
#3. Dip a toothpick into the cornstarch and water mixture and write with the
mixture on paper. Let the paper dry.
#4. To observe the message, dip the small sponge into the iodine solution and
carefully wipe the paper. Do not get the paper too wet. The message should
appear purple.

Performance Assessment:

The students will make the invisible ink #1 and #2 and write messages to
each other. They will also write an essay comparing and contrasting the two
types of invisible ink.

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