Rubber Chicken Bones

Clean chicken bones are soaked in vinegar so the acid reacts with calcium carbonate in the bone, removing minerals and leaving the collagen matrix flexible. After drying, the bones can harden in their new shape.

1. Rinse and dry clean chicken bones so no meat remains.
2. Place the bones in a container and pour in enough household vinegar to completely cover them.
3. Seal or cover the container and leave it at room temperature for at least 24 hours; longer soaks make the effect more pronounced.
4. Check periodically; when bubbles slow and the bones feel soft, remove one to test. They should bend without snapping.
5. If desired, gently tie or shape a softened bone into a loop or knot.
6. Let the shaped bones dry in air overnight so they set in the new form.
7. Compare the treated bones with an untreated control bone kept in water.

Emily's Science Lab - Rubber Bone - Vinegar Science Experiment - Emily Calandrelli:

Demonstration: Rubber Bones - Arizona Science Center:

📄 “Rubber” Chicken Bones - Fizzics Education: https://www.fizzicseducation.com.au/150-science-experiments/digging-dinosaurs/rubber-chicken-bones/?srsltid=AfmBOopqvkDdJhHhBWlbM4BRJeWWxXWcn93EPLp-rReHH_WFBU5e2wUf

• Test different acids such as lemon juice or diluted citric acid and compare how quickly bones soften.
• Compare white vinegar versus cleaning-strength vinegar to see the effect of concentration.
• Use different types of small animal bones (e.g., rib vs. drumstick) and note which flex more.
• Measure bend angle over time to create a simple time-versus-flexibility graph.
• Try partial soaking (one end in vinegar, one end out) and compare ends.
• Repeat with a control kept in plain water or baking soda solution to highlight the acid’s role.

• Wear safety glasses to protect eyes from splashes.
• Use gloves when handling vinegar and bones, especially if you have cuts on your hands.
• Work in a well-ventilated area; vinegar fumes can be irritating.
• Use only clean, fully de-fleshed bones; wash hands and surfaces after handling.
• Do not ingest any materials; keep food and drink away from the experiment area.
• Dispose of used vinegar down the sink with plenty of water; wrap and bin bones according to local hygiene guidelines.
• Adult supervision recommended, particularly when shaping bones to avoid snapping and sharp edges.

• What part of the bone’s composition changes during soaking? (The acid dissolves calcium carbonate minerals, leaving mostly the flexible collagen matrix.)
• What gas do you observe forming on the bones, and why? (Carbon dioxide forms as acetic acid reacts with calcium carbonate.)
• Why do the bones harden again after drying? (As moisture leaves and carbon from carbon dioxide is reabsorbed, minerals can reform at the surface and the collagen stiffens as it dries.)
• How does acid concentration affect the time needed to soften the bone? (Higher acid concentrations generally speed up the reaction, reducing the time needed.)
• Why is a water-soaked control bone useful? (It shows that water alone does not cause the bone to become flexible, highlighting the role of the acid.)