Mike, so harsh

I do a lot of new construction post cleanings and seal. Color sealing walls and even pans are awesome and permanent. I guarantee my jobs. If however the grout is impregnated with scum, scale, mold or previous penetrators I won't guarantee.
It's the level of cleaning that can ensure a good long lasting bond for any color sealer. I use a chemically and mechanically bonding sealer and I never have to apologize for failures. I've R&R'd a lot of shower pans and then color seal after grout cured a few days. Those jobs I warranty as well
Everyone loves acid cleaners but better think about testing and making sure that there's no acid sensitive stone anywhere near or they're paying for polishing. Even some ceramic glazes won't tolerate some acids.
Some of the non-acid glass restorers contain silica flour. They will micro scratch glass when using power tools to polish the scale from the surface. Cerium Oxide is the industry standard but it's not cheap.
If most of the residue is soap scum with the balance hard water scale I don't bother with using a turbo tool even though I designed it. Since there's a drain in the floor of every shower I've started using a rotomax zero degree nozzle on my pressure gun at about 1500 to 1800 psi with pretty high heat to zip the history right off walls, pan, and glass. Prespray is high pH and no agitation just multiple fine mistings to attack the bond.
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