Water seeps through concrete's pores, cracking its exterior and damaging the steel beams within. Sodium acetate seals these pores from the inside, says researcher Awni Al-Otoom of the Jordan University of Science and Technology in Irbid, Jordan. When brushed onto concrete as part of a watery solution, the salty substance sinks in and forms crystals, partially plugging the pores. The crystals create an even better barrier when wet, since moisture-a drop of rain, say-makes them swell to fill openings more snugly. The salt costs half as much as glue-like polymers and other common sealants. If Al-Otoom's results hold up in real-world tests, potato-chip tang could be protecting bridges within a few years.