10 Activity: Is Black Ink Really Black?

Supplies per student:

1 coffee filter

Several different black markers to test

Dropper or plastic pippette

1 cup of water (can be shared)

Question: Is black ink really black?

Directions: Distribute the coffee filters and advise students to make a single dot of each different pen in different areas of the filter. Share pens with others so a variety of pens are represented. Distribute plastic plates and have them place the filter on top. Distribute cups of water and have add a drop of water to each color spot. Some of the spots will spread out and display colors other than black.

Theory: Some of the colors than make up black pens are hydrophilic (water-loving) and will follow the water as it spreads out on the filter by capillary action. Some pigments are hydrophobic (water-fearing) and will stay put. A drop of acetone (see notes) may cause these drops to follow the acetone.

Grades: 1st – 4th

Time: 15 minutes

Clean Up: Filters can be dried and taken home or disposed in the garbage. Plates can be washed and reupsed.

Notes and Hints: Advise the students to only add a drop of water to each color spot. If available, add a drop of acetone (hydrophobic) to and spots that didn’t spread. Test out a variety of black pens before having the students do the experiment.

Image Credit: https://talesfromthecornerhouse.wordpress.com/2012/01/20/whats-in-black-ink/