Lenses for a laser is better to clean with 99%iso due to it barely leaving any residue when evaporating, but even that is a compromise.
What you really want is pure (“100%”) alcohol/ethanol to leave even less of trace.
Unfortunately most people or companies can’t buy pure ethanol due to the nature of alcohol laws, so a substitute like isopropyl is used instead since its usually "good enough "
Lenses for a laser is better to clean with 99%iso due to it barely leaving any residue when evaporating, but even that is a compromise.
What you really want is pure (“100%”) alcohol/ethanol to leave even less of trace. Unfortunately most people or companies can’t buy pure ethanol due to the nature of alcohol laws, so a substitute like isopropyl is used instead since its usually "good enough "