Ideally you should never have to strip and completely rebuild a floor’s finish – IF you do complete interim maintenance – including rebuilding the finish frequently with additional coats to replace the finish walked off.
And don’t spill anything that can penetrate the finish and discolor parts of it.
And don’t turn on the lights – UV light turns finish brown – eventually.
Since this never happens in real life commercial cleaners eventually have to strip all the old finish off – just like you would with paint or an old finish on a piece of furniture or molding in your house – and rebuild the finish.
The process is similar – the chemicals are different.
A lot of different things will strip the old finish off – alcohol (any organic solvent), high alkaline degreasers and “strippers” (the traditional option), very hot water (which is why janitors do their daily mop and autoscrub with room temperature water, not hot water) – but the best option is a “stripper” formulated by the same manufacturer as the finish, specially formulated to react with and break down the finish.
Did I already say I’m not a chemist? – I can’t give you a whole lot about the chemistry involved – but I can tell you that spending a little more on finding a stripper especially formulated for the brand of finish you are trying to remove is going to save you so much labor that a little research in finding the right product is time well spent.
The process, once you pick the product is to thuroughly clean the floor.
Mop the stripper on.
Let it work for 5 minutes or so – to start dissolving the finish.
Agitate with a low speed floor machine.
Vacuum up the finish and stripper with a wet vac.
Rinse / vacuum up rinse water.
Apply new finish.
The process to rebuild the finish before it needs to be stripped is similar – scrub the floor clean – but skip the the stripper / agitation piece and go right to applying new finish.