Jake doesn't mention this in his instructions, but my hunch is that the best way to apply the liquid is carefully, with a spray bottle, as you would for pie crust.

From what I've seen with less-than-satisfactory experiments with other recipes, the real trick here is water management. You want enough fluid to hold the stuff together, but not so much that significant amounts of the acid and base go into aqueous solution and start reacting with each other.

If you're using this stuff for learning about chemistry, you probably want to make sure you're using materials that aren't using the old Arrhenius definition of bases, or things are going to get very confusing. Here and here you can learn the difference between some definitions of acids and bases, and learn why baking soda is a base even though it doesn't have an OH- ion to release. You might also like the balanced equations of the reaction. And if you were wondering why anybody would call NaHCO3 "bicarbonate", well, that's a good question.

-- Cam