So I came upon this amazing formula for making an invisible ink , with could only be seen under UV/Black light.

How?
Glad you asked!

Black lights are not that different from any other type of light, whether incandescent, fluorescent, or just the age old candle flame. The difference is that black lights emit most of their light waves just outside the range humans can perceive, in the Ultraviolet (UV) part of the spectrum. When a UV light wave hits an object containing substances known as phosphors, those phosphors will naturally fluoresce, and glow.

Phosphors are present in many daily use objects like Vaseline, tooth whiteners, body fluid (you know, the gross ones...), bank notes, laundry detergent etc.
So, when you know, let's start.

Step 1: Stuff Needed

Get :
A Highlighter (Any, really, absolutely any)
Pliers
Hot Water
Empty Cup
A UV/ black light
A Water tight Jar.

Step 2: Take It Out

Depending on what kind of highlighter you have you can usually open them up with pliers. Don't destroy the highlighter trying to get it open. Once you get it open take out the tube of ink that is inside, and pull the tip (the part you write with) out of it with pliers.

Step 3: Microwave

Put the tube and tip into a cup of water. Put it in the microwave until it starts boiling.

Step 4: Into the Water!

Take out the tube with the pliers and squeeze all of the ink out into the cup. Do the same thing with the tip.

Step 5: Fin!

Add enough water so that you can see through the water clearly but it is still dark. Put the tube and tip back into the cup and put it in the microwave until it boils again.

Step 6:

Put the parts back into the highlighter and you have your invisible pen! Dip the pen into the ink and write with it! To save the ink put it in a water tight jar so you can refill your pen. Your ink will show up under a UV light or black light.

Make sure to vote for me!