Lately I've become sort of an amateur lens technician taking apart and cleaning old lenses.

Before anyone calls me an idiot, I've garnered the necessary equipment (spanner wrench, lens solution, JIS screwdrivers, ESD gloves, etcetera) and working acumen to do more good than harm for all the lenses I've taken apart.

The scourge of my existence however has been dust that is not visible in normal light, but is in great excess when a small light is shone through the lens. I work in an uncluttered environment and run a Honeywell HEPA filter prior to a project (air purifier, not laminar flow cabinet can't afford that shit)

A lens blower actually worsens the amount of dust that is not visible in normal lighting though it gets rid of visible dust, presumably from the fast-moving air leaving static buildup on the glass. I have had much greater success with a dry lens tissue but there is still a generous of non-visible dust.

Is there a technique or tool used to remove the remaining dust on optic elements? And yes even non-visible dust can affect contrast and sharpness, especially in backlit photos.