Evaporating mixtures of two liquids create hypnotic designs

Signature patterns are the result of differing surface tension

isopropanol ethylene glycol mix droplet

Droplets containing liquids with different surface tensions, like isopropanol and ethylene glycol (shown), bloom into intricate patterns as they evaporate.

A.P. Mouat et al/Physical Review Letters 2020

When liquids containing small particles evaporate, those fluids often leave behind fingerprints like coffee rings or whiskey webs (SN: 10/31/19).