Used to wrap a greasy pipecleaner around the spindle to cover the gap around the spindle-BB Cups.
then
There was a Zirk Kit , a stiff thick plastic tube went between the bearing cups , and the zirk tapped into it after passing thru the BB shell .
It also had a stack of O rings and a seal with it to go against the outside face of the cup, to keep crud from getting in..

later
I First got the Higher end Campag cartridge BB with my 'race triple' (internal spline, same as the hub lock ring)
then seeing the lower cost ones let me trap an O ring on the spindle , before I put the arms on [ external spline, ring wrench fixed]
single O ring fits tight between the arm, and BB face.

in addition..
A custom touring bike, building around a '90's Burly Tandem stoker's BB shell, we left the shell solid , TIG'd on the other tubes.

so it being a larger volume, and the oversize bearings were held in with Loctite and a snap ring, the Zirk
let me put in a lot of grease between the bearings , seals on the outside , none on the inside..
so it became fit and forget.


more recently UNxx went rough rather quickly winter commuting so I tossed it , already has a NOS GreaseGuard BB
for my Bike Friday-Rohloff bike .. they fit seals inside so grease is put in the inside , pushing the old out around the spindle .

Too bad no external bearing BB is made to do that..