Did a lot of colour-matching at work with Nessler tubes, filter disks and such. We also put what samples we could into colourimeters and, yes, spectrophotometers, both trad 'dial a wavelength' and, later, diode-array spectrum grabbers...

Snag with manual methods was you had to begin by assuming the sample was 'guilty', then sorta spiral in, happily discovering it was okay after all.

And, yes, you had to keep your optical prescription reasonably up-to-date.

I still remember having a dispute with a senior guy who said a brew was the correct colour, despite me thrice getting colour matches that were waaaay off. That was late on a Friday afternoon, when we'd few staff left to tie-break. I refused to sign it off, went home.

But, the following morning, I was waiting on doorstep of my optician. Though I'd no appointment, when he heard my tale, he urgently tested my colour vision, as-is, wearing my 'street' glasses, then again wearing my 'safety glasses'. Passed as excellent, wrote me a note to this effect.

Which saved me from near-lynching by posse waiting at work on the Monday morning. Seems batch had been signed as fit for 'filling' on the Saturday. Where the pre-start line check spotted the colour match was waaaay off. Team had to be sent home...

Careful examination of records showed the fourth 'Is OK' finding was not my writing, nor my signature. And, yes, I had the fresh note from my optician confirming that my colour vision was okay. A legendary 'CYA' !! Investigation discovered that senior guy had glanced at the colour, seen a pink unicorn, not my dun mare, over-ridden my findings . Seems he had, all un-aware, such poorly corrected vision that he and I had seen sufficiently different colours...

Yeah, right. Only, when we dialled up what I'd seen in triplicate vs what he claimed to have seen, once, the difference was so wide he must have been legally blind, un-fit to drive...

Given he was a rising 'Mover & Shaker' in our then-powerful staff union, us lab-rats reckoned he'd been given a 'plea bargain'. We were not surprised when, a few months later, a vacancy appeared across-site and he got the job...