Write an article based on this "Gather the necessary materials. Write on the paper with the jelly. Shine the black light on the paper."
Petroleum jelly is a fun ink to use because it will glow in the dark under a black light (UV light). To use this type of invisible ink, you will need petroleum jelly, Q-tip cotton swabs, white computer paper, and a black light.  Most of these materials should be easily found around the house. You can purchase a black light at a local superstore or online. Dip the cotton swab into the petroleum jelly until you have a small amount on the end. You don’t want a big glob of it because that will be difficult to write with. Write your message with the tip of the cotton swab. For best results, try to make the writing smooth, avoiding bumps from the jelly. To reveal the written message, shine a black light on the paper. You can even turn the normal lights out or look at it in a dark closet. The words you wrote will glow in the dark under the black light. You don’t have to wait for the jelly to dry completely before revealing the message.