If you didn't already know..
and if you play with the dilutions alongdide hydrogen peroxide in your HF you can remove redstains with your presprayJust use a weak ammonia solution in your TM jug.
It completely evaporates and .............doesn't leave a residue, self neutralizes .
And I said weak............no fear of ammonia smell
That’s the best explanation I’ve ever read about this topic.A point about sodium hydroxide. It is used in small amounts to modify pH. It is used in almost all of the high pH liquid pre-sprays on the market. If the pH is below 11 then it is used in small amounts. In short, the amount used in any formula varies significantly. A formula can have sodium hydroxide and be considered green if pH is 10 or below. It is processed from natural sources. Potassium hydroxide comes from potash in various places like southern Utah and Saskatchewan (close to the residence of my brother-in-law.
In powdered formulas, sodium hydroxide is typically combined with sodium silicate to form sodium metasilicate. The soidum silicate part neutralizes the corrosive impact of sodium hydroxide on metals. We use the sodium metasilicate as a corrosion inhibitor in rinse formulations. In powders the three basic components are sodium tripolyphosphate (STPP with pH <10), sodium metasilicate with pH > 12 and sodium carbonate with pH 11. Cost of sodium carbonate is X, sodium metasilicate is 1.5X and STPP is 4X. Your powdered pre-sprays below 10 will be more expensive than your powdered pre-sprays above 12. Most of the newer pre-sprays on the market use alot of sodium carbonate providing lower cost. Any tile & grout formula which leaves powdered residue is generally a result of too much sodium carbonate and too little STPP in the formula.