KitchenEasySafety: High Risk
Red Cabbage pH Ink
A magic ink that changes color with vinegar or baking soda.
Color
Purple, blue, pink — depends on pH
Yield
≈ 200 ml
Shelf life
1 week refrigerated
Boil chopped red cabbage, strain the purple water, and use it as ink that changes color with vinegar or baking soda.
- ▸By itself it's purple. Add vinegar — pink. Add baking soda — blue or green.
- ▸It's a working pH indicator and an ink at the same time.
- ▸Doesn't keep long, even refrigerated.
Steps
- 01
Simmer cabbage in water 30 minutes until liquid is deep purple.
- 02
Strain and reduce by half on low heat.
- 03
Split into jars; add vinegar to one for pink, baking soda to another for teal.
Materials3
- — 1/4 head red cabbage, chopped
- — Water to cover
- — Vinegar (for pinks/reds) or baking soda (for blues/greens)
Safety
Involves caustics, acids, or open flame. Full PPE and trained supervision recommended.
Hazards identified
- Acidic / corrosive etchant
Quick checklist
- ☐Wear goggles, apron, and acid-resistant gloves
- ☐Always pour acid into water, not the reverse
- ☐Neutralize and dispose per local hazardous-waste rules
- ☐Work in a ventilated area; keep food and drink out of the studio
- ☐Read each material's safety data sheet (SDS) before starting
- ☐Have water, soap, and a first-aid kit accessible
Heuristic guidance derived from listed materials. Always consult each material's safety data sheet (SDS) and a qualified instructor before attempting.
Notes
A great science-fair ink. Fugitive — for fun, not archival work.