Joint-Cap Technique

What is this ‘joint-cap’ technique?
You basically pull out the nozzle part of the Japanese cap with a pair of pliers and insert the New York FAT cap into the hole sideways. When the two caps are connected the New York FAT cap sticks out from the side of the Japanese cap, and when you hold the cap down the spray actually comes out from the New York FAT cap on the side. With this technique we were able to get a clean circular spray. This technique was still being used by some writers even until fairly recently.

Rack Gaki, “Japanese Graffiti” by Ryo Sanada/Suridh Hassan (Laurence King Publishers 2007)