How to Make Disappearing Ink?

Plan on writing an ugly note and getting rid of the evidence huh? Well, to make your disappearing ink; dissolve .10g of phenolphthalein in 2tsp. ethyl alcohol. Stir in about 90ml of water to creating a milky solution. Add 20 drops (more or less until darkening occurs) 3M sodium hydroxide. Alright, all done now don’t let it disappear!