Have you ever thought about why we add vinegar to water when we’re dyeing eggs? We’ve got the science behind dyeing perfectly-hued eggs, and parents, you’ll love this: It includes a DIY science experiment for kids, as well!
Science behind the coloring of Easter eggs:
- Adding vinegar to water makes it more acidic
- pH of 4: Approximately one tablespoon vinegar per half-cup water consistently yields smooth, pretty color
Why?
Egg shells are porous. The acidity of the vinegar breaks down the shell of the egg ever so slightly, so that the egg dye can infuse into the shell.
If it’s too alkaline (a higher pH), the eggs won’t dye as well; the color won’t penetrate the shell.
If it’s too acidic (a lower pH), the acid dissolves the eggshell too much, and reacts with calcium in the shell to produce bubbling that it will leave blank spots on the surface of the egg where the dye wasn’t able to attach.
Source: Darryl Holliday, assistant professor of food science at The University of Holy Cross
The Experiment
What you’ll need:
- At least 3 hard-boiled eggs
- Egg dye tablets or powder
- White vinegar
- Water
- Measuring cups and spoons
- Mixing spoon
- At least 3 cups for dyeing solution
- pH test strips (optional; available at drug stores)
TIP: look for egg dye kits made with natural vegetable- and fruit-based colorings, vs. artificial food dyes).
Procedure:
Prepare 5 different egg dye solutions using the following measurements:
- Vinegar Only : ½ cup + 1 tablespoon vinegar
- Vinegar + Water: 1 tablespoon vinegar + ½ cup water
- Water Only : ½ cup + 1 tablespoon water
In each cup, add egg dye coloring powder or tablet. Add vinegar-only solution to the first cup. Add vinegar-water solution to second cup. Add water-only solution to third cup. Allow to sit at least 5 minutes, up to 10 minutes. Carefully remove eggs from solution and observe the color saturation produced.
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