Why is it hard to open a tight container, like a jar lid or bottle cap, with just your bare hands, but when you grip with your shirt or a piece of cloth, it becomes no effort?

Question

Why is it hard to open a tight container, like a jar lid or bottle cap, with just your bare hands, but when you grip with your shirt or a piece of cloth, it becomes no effort?

In: Physics

Answer 1

So much bad advice here, without answering your question. Too many sharp metal tools. Why would you want a hole in your lid? Or sharp ridges around the edge ?

To answer your question: If your hand is clean and dry, it won’t slip. Most people don’t wash their hands first though. Oils reduce the friction coefficient, and it takes a tight grip to break the vacuum seal to permit the lid to spin off. So a cloth (not all cloth) can increase friction, so you don’t need to grip so tightly.

Want a solution? Safer than the sharp weapons solutions?

So the easier solution is to tap the edge of the lid (hold the jar upside down at an angle) on a cutting board. A couple taps and you’ll hear the seal pop as the vacuum releases.

The vacuum is what preserves the food (no oxygen, no spoiling)

Then the lid spins off easily.