Invisible Ink: A Citrus Painting Experiment

invisible ink citrus lemon lime kids

It’s summer and we’ve been doing a lot of citrus juicing in our home. Between my 4-year old expert juice squeezer and my almost 2-year old juice taster,  our simple and inexpensive juicer has been hard at work.

invisible ink science activity kids

While little Rainbow napped, Nutmeg and I gathered materials and set up the project. We talked about how we’d have to reveal the ink (lime juice) with the high heat of an iron or hair dryer, and she couldn’t wait to get started. She loves dangerous tools.

invisible ink citrus kids

We gathered our ingredients.

Here’s the full recipe:

5.0 from 2 reviews
Invisible Ink: A Citrus Painting Experiment
 
Author:
Recipe type: Science
Prep time:
Making time:
Total time:
 
Lemon juice is acidic, and acid weakens paper. When paper is heated, the acid burns and turns brown before the paper does.
Supplies
  • Lemon or Lime Juice
  • Paper
  • Paint brush or Q-tip
  • Iron
Steps
  1. Squeeze lemon or lime into a bowl.
  2. Paint the juice onto your paper with a paint brush or Q-tip.
  3. Wait for the paper to dry.
  4. Heat the paper with an iron, hair dryer, light bulb, or other heat source. Be careful that you don't hold it there to long, as it could burn the paper.
Notes
Experiment with other liquids: milk, orange juice, white wine, vinegar, and apple juice are good bets.

 

invisible ink citrus lemon lime kids

Just as we were getting started, baby R woke up to join us. She’s 22 months old now, and enjoyed the sensory experience of squeezing the limes with her bare hands, and then licking her fingers. According to my mom I used to eat lemons right off our tree, so this wasn’t too much of a surprise.

invisible ink lemon lime juice

The girls experimented with different colored papers and brushes. Afterwards I realized that Q-tips would have been perfect for this project, but we enjoyed the challenge of small watercolor brushes.

invisible ink citrus lemon lime kids

The papers dried pretty quickly on this warm day and we were able to get right to the fun part of burning the acid with heat. N’s grandma blows her hair dry every day, and N is obsessed with this tool. Obsessed. We ran the heat on the paper for about a minute with little success. I never blow dry my hair and have a cheap blow dryer for projects like this, and maybe that’s why? In any case, we decided to move on to the iron.

invisible ink citrus lemon lime kids

I folded a thick towel, placed the art on top of it, and she ironed away. In most cases an ironing board would have been better, but ours pulls awkwardly out of the wall and it’s too tricky to get the three of us around it safely. This worked perfectly and only took a few seconds to show its results.

invisible ink citrus lemon lime kids

N’s picture of her and her dad (he’s above her head, slightly visible in all his heated lime acid glory).

invisible ink citrus lemon lime kids

I really like how the abstracted images turned out and wished I had joined them once I saw how cool these looked. I usually join in when we’re creating and somehow forgot to on this round.

How about you? Do you find yourself doing projects with your kids, or are you in more of the facilitator mode? And what do you think about the new recipe card tool and header?