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There's a secret "tap spot" on a Heinz ketchup bottle
💡 Ketchup is a shear-thinning fluid — it stays put at rest and only flows when you hit it with force, so tap the neck rather than waiting on gravity.
Whacking the bottom of a glass Heinz bottle is the wrong move. The company's own tip: tap the embossed "57" on the narrow part of the neck. That spot sits at about the right angle to nudge the stuck plug of ketchup toward the opening rather than compressing it deeper into the bottle.
The deeper reason is that ketchup is a non-Newtonian fluid — specifically shear-thinning. At rest it behaves almost like a soft solid and refuses to pour; apply force (a tap, a shake, a squeeze) and its internal resistance, or viscosity, drops sharply so it suddenly flows. That's also why it lurches out all at once after you've been patiently waiting: the force finally overcomes its at-rest structure.
So the trick isn't magic in the number 57 — it's applying a sharp, well-aimed force where the ketchup is jammed, instead of waiting for gravity that a resting fluid actively resists.