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Make Your Science Study Fun with Invisible Ink DIY

By Shreya PatroJuly 08, 2022
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When Science and Creativity Come Together, Magic Happens

Making invisible ink DIY to write secret messages is something new to try. However, you can do it yourself at home with simple items. There is no strict need for any particular chemical to buy. Any chemical will do the job if you know how to use it. So, here you can learn how to make invisible ink. Let's get started!

Invisible Ink - What is It?

It is a substance that you use to make a note. The message is written but remains invisible until the ink is revealed. Use a cotton swab, toothpick, tulip, or just your finger to write the letter. Let the writing dry. If you don't want the paper to look like a blank one, put a note with regular ink in the corner beside the secret message.

For that, a ballpoint pen or ordinary pencil is enough. This will act as a cover message for the actual message. Avoid fountain pens, as their ink can run into your invisible ink. For the same reason, you can choose white paper instead of lined paper. 

How you reveal the message depends on the ink used. In most cases, invisible inks are made visible when you put the paper on heat. Iron the paper and hold it over a 100-watt bulb. Now the message will soon be visible.

Other than that, hidden messages are visual when applying a spray-on or wiping the paper with another chemical. Sometimes, statements are revealed by shining an ultraviolet ray on the paper. And, sometimes the message is revealed by setting it on a radiator, ironing the paper, and placing it over the oven from a distance (lower than 450 degrees F fire).

Invisible Ink

Invisible Ink

The chemicals you can use as inks are:

  • Acidic Fruit Juice (like lemon juice)

  • Baking Soda

  • Onion Juice

  • Vinegar

  • Diluted Cola

  • Diluted Honey

  • Milk

Chemicals you can use

  • Cobalt chloride (developed by potassium ferricyanide)

  • Lead nitrate (formed by sodium iodide)

  • Sodium chlorine or tablet salt (developed by silver nitrate)

  • Ammonia (developed by red cabbage water)

Inks Developed by Ultraviolet Light

Most inks that reveal when you shine a dark light on them are the ones that would become visible on putting the paper on heat. Shining on the dark stuff is still fantastic. The chemicals to try with ultraviolet rays are:

  • Bodily Fluid

  • Dilute detergent

  • Tonic water

  • Vitamin B12 (dissolved in vinegar)

How to Make Invisible Ink?

  • Mix 50% baking soda and 50% water in a small cup

  • Write a secret message on paper using a mixture and paintbrush

  • Wait till the paper dries

  • Pass the paper to whom you wrote the message

  • Use a sponge or brush to paint the paper with milk or juice.

Invisible ink DIY

Invisible ink DIY

5 Ways to Make Invisible Ink Experiment 

Here are the 5 ways of invisible ink experiments you can easily do at home. Let’s start with the process.

1. Milk and Pencils

Use a cotton swab or toothpick to write a message with whole milk. Let that dry completely. Rub the graphite of a pencil on sandpaper over the message. So, that a graphite powder falls onto the paper, gently rub it till the message appears.

2. Heat Activated

Use a cotton swab or toothpick and write the message with lemon juice or vinegar milk. Any other fruit juice will do the job. Keep the paper aside to dry for some time. Then heat the message paper with the help of a hair dryer, hot iron, or holding it near a light bulb. Warm it in the oven for 5 to 10 minutes.

All the liquids are mild acids that weaken the part of the paper where you wrote the message. The acid still stays on the paper after the invisible ink dries. On heating the paper, the acidic message turns brown.

3. Wax Resist

Write a message with a white crayon. Then, paint the message with watercolours. Using colours like red, blue, and green works best. Wax repels water. The wax paper is useful as it does not get wet.

4. Acid and Bases

Mix 2 tablespoons of baking soda with an equal amount of water. Put a cotton swab or toothpick dipped in the mixture. Write the message. Let the paper dry. Once it dries, use a cotton swab or paintbrush in grape juice to paint over the written message. The baking soda is the base that reacts with grape juice. Acid produces a different colour on the paper.

5. Black-Light

Use a toothpick or cotton swab to write your message with a white liquid made of laundry detergent. Now dry the paper completely. Hold the paper under a black light, and the message will be visible. This is because detergent has phosphors that glow in the sun's ultraviolet light (and the black light too). Thus your secret message appears bright.

These are some of the invisible ink experiment explanations. Try these at home with your friends or kids and see amazing results.

Is Invisible Ink Real?

You have seen detective movies where they pass the secret message. That is a trick of invisible ink application. You get to experiment with the magic of science with the implementation of invisible ink. Kids who find science subjects boring are subjected to such fun activities.

Make them know about the wonders of chemicals, and their interest will automatically improve. Any acidic fruit juice (like lemon) gradually weakens the paper. That is why the painted portion turns brown faster. The invisible ink is real, thanks to its chemical properties.


Studies are never that boring if you apply the knowledge practically. Fun activities can also be part of the learning experience with a little brain usage. Also, with a practical example, children tend to remember a lesson for a longer time and with better logic. No bookish information can serve as much as a practical example. Learn how to make invisible ink pen and enjoy your day with new fun lessons.