Wilson wrote:

btw, what is the chemical that makes lime work?
Is it calcium hydroxide for hydrated lime? or was is something like
caclium carbonate? :S

Limestone, seashells are CaCO3, calcium carbonate (insoluable in water).
CaC03 will react with acids, but slowly. This is why we worry about
acid rain on our statues, etc.

Gypsum is CaSO4, calcium sulfate (insoluable in water). It is used to
break up clay and for wallboard.

Lime is CaO, calcium oxide. It reacts with water to form CaOH, calcium
hydroxide. CaOH is very caustic (basic) and will lower pH dramatically.
CaO will hydate by attracting water molecules, but not reacting with
them. Hydrated CaO is much safer to handle.

[I believe the info above is correct. However it has been close to a
half century since I have been in a chemistry class.]