Invisible Ink

When i typed in invisible ink to you tube a few different options appeared. invisible ink which is visible with a UV light, making invisible ink from lemon juice and disappearing ink which involves phenolphthalein and an acid based reaction. Originally we wanted to buy a pen which makes a mark then disappears and reappears but apparently this does not exist. In this case we may either have to find a way to make this ink or edit the text accordingly. Below there are a few videos which show these methods.