On Sat, 23 Feb 2013 06:02:28 +0000, Ripple Whine wrote:

Clearly it removes rust - but HOW does it remove calcium oxide (aka lime)
and what does it mean by organic deposits (other than carbohydrates)?

I have no idea, but googling, I see that phosphoric acid reacts with calcium
oxide to form calcium phosphate and water.
http://www.chegg.com/homework-help/q...water-q1594465

So the question is really why would we want to convert toilet bowl
limescale to toilet bowl calcium phosphate [Ca2(PO4)3].

Offhand, my guess is that mixing the acid plus the base, nets a salt
which is (I'm guessing) soluble in water - hence easily cleaned.

Since my shower stall is VERY stained with hard water deposits, I might
try it (but I generally use LimeAway) as a separate experiment for the team.

The MSDS for Lime Away says it's 2.5 to 10% Sulfamic Acid (CAS 5329-14-6).
http://www.rbnainfo.com/MSDS/US/LIME...US-English.pdf

I have never heard of Sulfamic Acid but Wikipedia says it's used to
remove rust and lime by converting them to soluble calcium and iron salts.
http://en.wikipedia.org/wiki/Sulfamic_acid

I'm guessing that the phosphoric acid mixes with the lime to create a
salt which is then washed away by dissolving in water.