Shake and Slosh

For opaque plastic bottles, estimate contents by weight and sound. Professional chef technique during rush.

The technique:

1. Pick up bottle
2. Shake gently side-to-side
3. Listen and feel

The heuristic:

• Heavy + No Sound = Full
• Heavy + Slosh = 3/4 Full
• Light + Loud Slosh = < 1/2 Full (Warning Zone)
• Light + No Sound = Nearly Empty (Buy Now)

Why it works: Your hand is excellent at estimating weight. If bottle feels “airier” than usual, trust that instinct.

Best for: Plastic bottles (water, soy sauce, milk), metal containers.

Accuracy: ±10% with practice. Not precise, but precise enough for Two-Bin System trigger.

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North: Where this comes from

• Proprioception (body’s sense of weight and position)
• Sound Resonance (liquid volume affects sound)

West: What’s similar?

• Tapping Watermelon (sound indicates ripeness)
• Gas Tank Shake (old cars, estimate fuel)