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/
Media Attributions
- black