how strong is prince rupert's drop

Prince Rupert’s drops are incredibly strong in the bulbous head—far stronger than ordinary glass and even comparable to high‑strength steel in surface stress—but they are also extremely fragile at the tail, which can trigger an explosive shattering of the whole drop.

Basic idea

• The head of a Prince Rupert’s drop can survive hammer blows and very large compressive forces without breaking.

• The tail is the critical weak point: snapping it with light finger pressure causes the entire drop to violently disintegrate into fine glass particles.

How strong is the head, numerically?

• Lab tests show the head can withstand compressive loads on the order of 10,000–18,000 newtons in some experiments before failure (that’s like putting roughly 1–2 tons of force on it, depending on setup).

• The surface of the head is under huge compressive stress , measured around 400–700 megapascals (MPa) in detailed optical studies.

• Those surface stresses are in the same ballpark as many high‑strength steels, which is why people sometimes say the head is “stronger than steel” under certain kinds of loading.

Why it’s so strong yet so fragile

• When the molten glass drop is quenched in cold water, the outside cools and solidifies first, locking in compression at the surface while the interior is left in tension.

• Cracks at the surface tend to run parallel to that compressed outer layer, so they have a hard time getting into the inner tensile zone—this is what makes the head so tough under impacts and compression.

• The thin tail, however, gives cracks a direct path into the highly stressed interior; once a crack gets in, it races through the drop at up to about 1.5–1.9 km/s , causing the famous explosive shattering.

How this compares in everyday terms

• You can smash ordinary glass easily with a small impact, but a good Prince Rupert’s drop often survives direct hammer blows on the head that would instantly destroy regular glass objects.

• Yet a small flick or pinch of the tail is enough to release all that stored internal energy, and the drop essentially “detonates” into dust‑like shards.

Information gathered from public forums or data available on the internet and portrayed here.