Find some glow-in-the-dark powder. Look in the craft section of retail stores or in specialty craft stores. Halloween costume shops might also be a good source. You can also order glow-in-the-dark powder online from manufacturers like Ready Set Glo.
Buy an ink refill kit. You can do this with color or black-and-white ink cartridges. Purchase an ink refill kit that is compatible with your printer.
Place 1/4 tsp. of glow-in-the-dark powder in a microwave-safe bowl or container.
Mix 3 tsp. of the printer ink with the glow-in-the-dark powder.
Microwave the mixture for 30 seconds to dissolve the glow-in-the-dark powder. Stir it well after you take it out of the microwave and let it cool for a few minutes.
Use a syringe to suck up the ink mixture and apply it to the refill holes on your empty ink jet cartridge. The refill holes may be under the label of the cartridge or you may have to remove the plastic cap. Check the instructions for your ink cartridge to find the refill holes.
Insert the ink cartridge in your printer, run the cleaning cycle a few times and print out a test document. You must let the glow-in-the-dark ink charge in the light for a little bit before it will show up. Turn out the lights and admire your handiwork.