Directions for the invisible ink science experiment: Mix together 1/4 cup of baking soda with 1/4 cup of water. Using warm water will help dissolve the baking soda a little better. 2. Use a cotton swab to write your message in invisible ink on a piece of white paper.

Grape juice indicator. Purple grape juice changes its color depending on the pH of the solution. Vinegar is acidic and turns grape juice pink/red. Baking soda is alkaline and turns grape juice dark green.

When we spread the grape juice across the paper, the natural fruit dye changes color as it touches the streaks of baking soda crystals, but remains the original color in the other parts of the paper.

WHY IT WORKS: Mixing a base (baking soda) and an acid (grape juice) together creates a chemical reaction. The chemical reaction causes a change in the color making the invisible message appear.

How to Make Invisible Ink

1. Step 1 – Mix. Mix ¼ cup baking soda and ¼ cup water.
2. Step 2 – Wet your brush. Dip a cotton swab, toothpick or paintbrush into the mixture.
3. Step 3 – Write your message. Write a message on a white piece of paper and allow it to dry.
4. Step 4 – Apply the decoding stain.
5. Step 5 – Reveal the message!

Baking soda and grape juice react with each other in an acid-base reaction, producing a color change in the paper. The baking soda mixture can also be used more diluted, with one part baking soda to two parts water. Grape juice concentrate results in a more visible color change than regular grape juice.

Lemon juice—and the juice of most fruits, for that matter—contains carbon compounds. These compounds are pretty much colorless at room temperature. But heat can break down these compounds, releasing the carbon.

Squeeze some lemon juice into the bowl and add a few drops of water. Mix the water and lemon juice with the spoon. Wait for the juice to dry so it becomes completely invisible. When you are ready to read your secret message or show it to someone else, heat the paper by holding it close to a light bulb.

Lemon juice is the invisible ink (freshly squeezed lemon juice is best, but bottled lemon juice also works). Use a fine paintbrush (cotton swab or matchstick) to apply the lemon juice to the paper and write your secret message.

Write it: Use a cotton swab or toothpick to write your message with vinegar, milk, lemon juice – or really any fruit juice will work. Let the paper dry completely. The acid also stays on the paper after the invisible ink has dried.

Milk is an effective and readily available form of invisible ink. Write the message with milk, let it dry, and watch it disappear. Here’s how to use milk as invisible ink to write and reveal secret messages. Dip a paintbrush, toothpick or stick into milk and write your message on paper.

One very simple form of invisible ink is heat activated. When the ink is exposed to heat, such as under an iron or over a candle flame or 100-watt light bulb, the acids in the liquid turn a different color and the message becomes visible.

This ink can only be seen when illuminated by a UV or Blacklight emitting in the 350nm – 385nm light range. The ink is permanent and can be applied to paper, some plastics, skin, wood and almost any substance. The ink does not wash off, but will eventually wear off if applied to skin.

Any of the following for your invisible inks:

• Any acidic fruit juice (e.g. lemon, apple, or orange juice)
• Onion juice.
• Baking soda (sodium bicarbonate) (or 1 M sodium hydrogen carbonate)
• Vinegar (or 1 M ethanoic acid)
• Dilute cola.
• Diluted honey.
• Milk.
• Soapy water (or 0.1 M sodium carbonate)

Nazi death camp prisoners used their urine as invisible ink to write letters detailing the horrific medical experiments they were subjected to, it has emerged. Due to an acid reaction with the paper, the urine soon lost its colour and became invisible. To read the hidden message, recipients had to heat up the letters.

security ink

Urine is chock full of nitrogen, potassium and phosphorus, which are the nutrients plants need to thrive—and the main ingredients in common mineral fertilizers.