Secret Sour Sayings




About: I am in my third year of my electrical apprenticeship. This is my second career; formerly I was in the firefighting / EMS field. I enjoy my work and am always curious about new hardware (devices, wire, con...

How to produce secret messages without special ink or equipment

Step 1: Collect Materials

Obtain the following
- Lemon Juice
- Cotton swabs
- copy paper
- a heat source

Step 2: Creating Message

Dip a cotton swab into the lemon juice.
Make sure it is not too saturated with the juice.
Write your message onto the paper.

Allow the paper to dry before moving to the next step.

Step 3: Heat It Up!

After drying apply heat to the paper.
Caution must be used in this step so as to not burn the paper.
We used a burner on our gas stove on the lowest setting.
Move the paper so one spot does not become too hot.

Step 4: Read Your Secret Message

The message will appear on the paper in a light to medium brown color.



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    7 Discussions


    11 years ago on Introduction

    When I was a kid my grandpa showed me how to do this, but we just held the paper up over a desk lamp, and the heat from the light bulb would do the job, i suppose that energy efficient bulbs don't get hot enough, but I tried it with my halogen desk lamp and it worked a treat


    11 years ago on Introduction

    If lemon juice is not available, plain old cow's milk does the same thing. We did this on one boring Saturday that suddenly became a whole lot less boring.


    12 years ago on Introduction

    Neato. Will the message appear if the paper is simply left out for a while?

    1 reply

    Reply 12 years ago on Introduction

    Not sure. This was a school experiment / assignment for my son Lucas. We will try that though!


    12 years ago on Introduction

    Doing this as a kid (Geek Jr now turned Sr I suppose) an old electric clothes iron turned out to be the killer app for the reveal. We tried candles, bunsen burners, etc (no gas stove) but they seemed to mostly set fire to it as it became partially sorta kinda shown, not that that's not fun in itself and a good "first shot" just for effect but a little ungratifying somehow in that the message gets destroyed. An iron moved roughly as if ironing a shirt or impromptu laminating something will show it up real fast and smooth, probably not even messing up the iron but using a garage sale "50c. WORKS!" one might not hurt - it's always good to have one that you can afford to kill anyhow.


    12 years ago on Introduction

    You are the smartest nephew in the whole world! I loved your experiment and I cannot wait to see more of your cool experiments! Love Auntie Jill