Apple as Invisible Ink

The Use of Apple Extract/Juice as a Disappearing Ink

The purpose of my study is to test if apple extract/juice can be used as a disappearing ink

The following are the procedures used to make a disappearing ink using the apple extract. The following are the materials; Q-tip, paper, apple juice and a Candle (any source of heat will work, ex. lamp, iron, oven). Begin by pouring a bit of the apple juice into a bowl. Use a q-tip, toothpick, or a paintbrush to write your message on the paper.

Let the paper dry thoroughly. This will take about an hour. To decode the message, you will need to heat up the paper. The best way to do this is with a candle. Hold the paper over the candle until the words become visible. The words will become a brown color as they are heated up.

The result of my study is that apple extract/juice can be used to make a disappearing ink.

Based from the date gathered, the following conclusions were drawn: It works because the apple juice oxidizes in the air. Heating it causes that process to speed up. The juice will turn brown on its own in time.

Chapter 1Problem and Its Background

IntroductionApples are obtained from the medium sized tree belonging to the rosaceae family. Scientific name: Malus domestica. The apple tree is originated in the mineral rich mountain ranges of Kazakhstan, and is now being cultivated in many parts of the world. Apple fruit contains good quantities of vitamin-C and beta-carotene. Vitamin C is a powerful natural antioxidant. Sliced apple turns brown on exposure to air due to conversion in iron form from ferrous oxide to ferric oxide. Background of the Study

Juice extracted from the apple is used to make invisible ink. Since apples oxidizes when exposed to air turning the color of the juice on paper to brown, heating it up makes the process faster. Statement of the Problem/Objectives

Problem # 1: Can we use apple juice extract as an invisible ink? Alternative Hypothesis: Yes, we can use apple juice as an invisible ink. Null Hypothesis: No, we cannot use apple juice as an invisible ink. Problem # 2: Is apple juice a better alternative than other materials? Alternative Hypothesis: Yes, apple juice is a better alternative. Null Hypothesis: No, other materials such as baking soda or lemon juice is a better alternative. General Objectives:

1. To be able to investigate if apple juice can be used as an invisible ink Specific Objectives:1.To be able to use apple juice as an invisible ink2.To be able to know how fast the juice oxidizes which would make the hidden words visible. Significance of the studyThis study aims to find out if apple juice is a good source of invisible ink compared to other fruit juices or materials. Scope and LimitationYou need to extract a lot of juice from the apple to be able to complete words on the paper compared to other materials which is readily available. Definition of TermsApple – a fruit which is considered by everybody as delicious and healthy. Color may be red or green. Invisible ink – an ink that is not visible to the naked eye.

Chapter IIReview of Related LiteratureThe world as we know it began with the apple. According to Genesis 3:6, Eve partook of the forbidden fruit, gave it to Adam and their eyes were opened. This fruit of knowledge is generally represented by the apple. Were it not for Eve’s transgression, mankind would never have been born. In the eyes of Christians, at least, our world began with the apple.

Malus pumila, the paradise apple has been symbolic of many things throughout history. The genus name Malus comes from the Latin root “mal” which means bad or evil. In the Garden of Eden it represents sin and knowledge. “…the apple of my eye” are the words used by Jehovah in the Old Testament of the Bible, to describe his favored people. The ‘apple’ of the eye is the pupil, the center. God said he kept the children of Israel in the apple of his eye as a way of saying to them that they were central and favored, that he watched over them even in their trials.

Cutting an apple cross-wise will reveal more symbolism. The shape revealed is a five-pointed star. This pentagram, though often mistaken for a satanic symbol, is actually a Christian symbol which represents the atonement. This five pointed star is also called the Star of Bethlehem, representing the star that appeared at the birth of Jesus Christ. The seeds within the star of the fruit represent the Resurrection and Immortality or Rebirth, as this is how the fruit continues its life. This one fruit symbolizes the Birth, Sin and Death of man, then the Birth of a Savior who will Atone and Resurrect him to Immortality and Eternal Life.

This symbolism was carried though to several ancient pagan cultures as well. The Scandinavians had their goddess, Iduna whose name meant ‘at-one-ness,’ very close to the word ‘atonement.’ According to legend, she tended the apple orchards at Asgard a land for the Immortals. To Asgard the other gods went each night to renew themselves. Their immortality depended on partaking of Iduna’s apples.

Like Asgard, Avalon was another place for the Immortals. It was believed that Celtic heros like King Arthur didn’t die but sailed through the mist to reach Avalon. Avalon was the “Apple Island”. The name came from the Welsh word “afal” or apple.

The Irish mythological heros were summoned to Emain Ablach, (Emain of the Apple Trees) or the Avalon equivalent, “Avallach”. This was done by an “other-worldly woman who brings the hero a silver-white blossomed applebranch from Emain…” Some believe these legends to be rooted in descriptions of druidic ceremonies.

In addition to being a fruit rich in symbolism, there is much plant lore assigned to the apple. Apple boughs hung above the door frame of a house are said to bless the couple that resides therein with added peace and love. Others have used the apple in a love spell that involves cutting the apple cross-wise and sharing it with the one that you love to increase the attraction. In Danish folklore, however, apples are believed to wither around adulterers.

Many American children have bobbed for apples on Halloween. This child’s game may have originated from and Irish Tradition, “La mas nbhal.” This was “the feast of the apple gathering” which took place on All Hallow Eve. There was a spicy cider and toast beverage in which apples were floated. “It was usual for each person who partook of the spicy beverage to take out an apple and eat it, wishing good luck to the company.”

In England on Christmas Eve, there once was a popular custom called, “wassailing the orchard trees.” The farmer with his family and workers would honor the most productive trees in the orchard with cider and hot cakes while saying the following toast three times: Almost everyone has eaten an apple, but have you ever asked the question where do apple trees grow?

The apple trees we know today originated from the a wild apple tree that was native to Central Asia. It can still be found growing in the mountainous regions of Kazakhstan, Kyrgyzstan, Tajikistan and China. Amazingly, this original apple tree is the ancestor of almost every variety of apples that are available today, but unfortunately this species is not listed as vulnerable to extinction.

Most species of apples prefer a cool or temperate climate for optimal growing conditions. They tolerate cold conditions very well, but should be planted in full sunlight and away from any frost pockets (the area where cold air settles). They require some maintaining, such as watering and fertilizing, but are generally easy to care for. There are some specially developed species that can tolerate hot and humid weather, but most apples are still grown in cooler regions. Many countries now grow apples for commercial purposes.

China and the United States are the world’s top apple producers, followed by Iran, Turkey, Russia, Italy and India which all produce over two million tonnes per year. The world production of apples now sits at just under sixty five million tonnes. Within the United States over 60% of total production takes place in Washington state where conditions for growing apples are ideal

Chapter IIIMethodology

Materials:To make a disappearing ink, the following materials are used: toothpick or paint brush, paper, apple juice and a candle (any source of heat will work ex. Lamp, iron, oven).

Procedures:Begin by pouring apple juice into a bowl. Use a toothpick or paintbrush to write your message on the paper. Let the paper dry thoroughly. This will take about an hour.

To decode the message, you will need to heat up the paper. The best way to do this is with a candle. Hold the paper over the candle until the words become visible. The words will become a brown color as they are heated up.


By using apple juice extract, we were able to make a decoded message and make it disappear in paper. To decode the message, a candle was used as a heat source. After a short time being exposed to heat, the message will begin to darken to its pale brown color, revealing the message.


Because of the acidic properties of the apple juice, the written words after drying will blend in with the color of the paper making it look like it disappeared. Apples also contain fruit acid that when it is applied to paper, it weakens the paper material. When the paper is heated, the remaining acid on the paper turns brown revealing the message.


This investigatory project is about making disappearing ink out of apple juice extract. We were able to make a decoded message disappear in paper using this extract.


The apple juice extract is an effective ingredient to make decoded messages in paper.


The use of a candle or any other heat source should be done with caution. The heat emanating from the heat source may be strong enough to ignite the paper. Make sure you ask for assistance when doing this experiment.

Other fruit extracts may be used in making disappearing ink. Example: Lemon or grape.