What critical mechanical innovation did the Bíró brothers implement to handle thick ink without clogging?

Answer

A tiny, rotating metal ball

The brothers engineered a delivery system where a small metal ball sits snugly in the tip, rolling to pick up the thick ink from the reservoir and depositing it evenly onto the writing surface.

What critical mechanical innovation did the Bíró brothers implement to handle thick ink without clogging?

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How This Pen Changed The World - YouTube

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