Ammonia can also be used to neutralise the pink colour and remove it but it is less permanent as it has no buffering effect and I believe the fabric will absorb oxygen from the air and it may turn pink again. Sodium Bicarb will prevent this because of its high alkalinity.
Doug, with ammonia you set up an equilibrium where the free base is a gas. Le Chatelier's principle leads to the suite turning pink again eventually. I have posted about this before, but basically you want an irreversible reaction.
http://en.wikipedia.org/wiki/Le_Chatelier%27s_principleBicarb is a more permanent solution as it creates an irreversible reaction (well under normal conditions at least)
Carpetguy, this is chemistry not physics.
What does it do to reverse the colouring? Essentially, it grabs a proton and turns into carbon dioxide and water. In real life, it raises the ph a bit.
Hope this helps
Graeme
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