Moisture initiates cure but other substances can also cause cure to happen.
The basic way CA's work is that they contain an acid inhibitor which prevents the homopolymerization reaction from occuring in storage. When the CA contacts a substrate with surface moisture present, the moisture reacts with the acid inhibitor and neutralizes it - thereby removing the "shackles" from the CA molecules and they then immediately begin their cure reaction. The amount of stabilizer in CA is tiny and can be measured in parts per million, therefore very little moisture is needed to permit polymerization.
Where kicker becomes necessary is on surfaces devoid or nearly devoid of moisture, and on surfaces that are acidic in nature - wood and paper are good examples of the latter. Acidic surfaces inhibit cure just as the built in stabilizer does. Therefore on these types of materials, cure may be delayed or inhibited depending on their pH level and moisture content. On the other hand, surfaces that are alkaline (pH > 7) promote cure. Thus as some folks advocate, baking soda accelerates cure as it is alkaline. However, every time I have tried it the results were absolutely terrible in comparison. I use nothing but real kickers, and hold to the opinion that cheaping out on CA catalyst is a waste of time on a model worth several hundred dollars and that needs quality glue joints to survive.
CA in plastic bottles has a life span - moisture slowly permeates these containers, just like it does to plastic fuel jugs. This is why I do not advocate placing bottles of CA back in the fridge after opening them the first time, and why I recommend allowing them to come up to room temp before opening when first removed - atmospheric moisture will condense on the inside of the bottle and on the surface of the CA much more when it is cold.
While moisture does indeed initiate the cure reaction through neutralization of the inhibitor, you really have to be careful not to add too much - otherwise you end up with a lot of trapped moisture and this can result in mediocre properties in the end. Too much surface moisture, while certainly allowing rapid cure, can cause havoc at the interface between the adhesive and the substrates. Basically, instead of bonding to the substrate the adhesive can be prevented from doing so by a film of water. That's not good.
CA kickers are an aromatic amine, and yes Shannon they are a true catalyst. They do not participate in the actual polymerization reaction, rather they promote it by neutralizing the inhibitor. Because so little of it is required (generally about 98% of these kickers is volatile solvents) the final bond integrity is very good, WHEN properly applied. Dousing the parts in kicker is a great way to cause such a rapid reaction that the exotherm causes blooming, with the end result a wad of weak brittle foam and very little useful adhesive actually bonding the substrates. You don't want to trap solvent in the CA matrix, so don't marinate the parts then immediately bond them - either lightly surface spritz them (LIGHTLY, and from a few inches) or else pre-treat one surface, then let it sit for a moment for the solvents to evaporate. As I mentioned in another post, the catalyst remains active for a while - on porous substrates several minutes.
Like many things, kickers, whether commercial (yea) or homebrew (boo), are best used with care and in moderation. Just because the adhesive cures doesn't necessarily mean you achieved the best bond that was possible.
Mike D.