Solved cryptogram
Aluminum corrodes instantly, then stops. The oxide layer it forms seals the metal underneath.
Chemistry Facts, sourced to Royal Society of Chemistry.
What it means
Fresh aluminum is highly reactive, and a clean surface oxidizes in a fraction of a second. The oxide happens to be tough, transparent and tightly bonded to the metal below, so the reaction stops itself after a layer a few atoms thick. Iron oxide flakes off instead and lets the attack continue, which is the whole difference between a rusted car and an old ladder.
The claim comes from Royal Society of Chemistry, and the page it comes from was read on 2026-08-27 to confirm it still says this.
This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.
Solve it yourself
This fact is a cryptogram here: 77 letters over 18 different ones, graded medium.
- SourceRoyal Society of Chemistry
- CollectionChemistry Facts
- Difficultymedium
- Length77 letters, 18 of them different
Nearby in the collection
The facts either side of this one.
- Royal Society of Chemistrymedium, 75 letters
- Royal Society of Chemistrymedium, 77 letters
- Royal Society of Chemistryhard, 73 letters
- Royal Society of Chemistrymedium, 68 letters
About as hard as this one
Scored closest to it by the model behind our guide to solving cryptograms.
- Royal Society of Chemistrymedium, 74 letters
- Royal Society of Chemistrymedium, 79 letters
- Royal Society of Chemistrymedium, 73 letters
- Royal Society of Chemistrymedium, 74 letters