A coil reservoir works on the theory of liquid suspension. The ink is held in the coil and the coil sits on the vent and thus, you have put a little pot of ink on top of your nib. I fix the coil to my nib holder with simple, black binding tape. Not the prettiest solution, but nicer than masking tape.
Here’s how you make one:
1. Using the tip of a drafting pencil, or the end of a paintbrush or any form that comes to a point, hold a metal wire with your thumb about 1/2 inch from the base. I found 26 gauge stainless steel wire to be thin enough to work easily, but thick enough to hold its shape. You can get a big roll of it from home depot for about 5 dollars.
2. Coil the wire tightly around the tip, so it forms a slight funnel. This may take some practice. The first coils I made were too loose, and wouldn’t hold ink. Now I can make one in a few minutes that is coiled nice and tight. The coil itself should be about 1/4 of an inch. Leave a good amount of lead in the back.
3. Now you have your coil! Trim down the lead at the top.
4. Sweet! Now, you just need to tape the lead in the back to your nib holder.
5. You want to position the coil so it is laying over the vent of the nib. This will make sure the ink is getting drawn into the nib.
6. Once you have it positioned, you just tape it down and you’re done!
Here is the difference between reservoir and no reservoir in a vintage nib with a lot of spring. Your ink will extend even further if you use a nib that is a little stiffer.
I have seen photos where folks have attached their reservoirs in a more aesthetically pleasing way, but I am interested in performance more than looks, and the coil eventually rusts, so I cannot justify spending too much time crafting a thing that I will have to throw out in a few weeks anyhow.
Important: Do not leave the reservoir sitting on your nib overnight. Simply bend it up so the nib can dry, or better yet, remove your nib from the holder all together. This will keep your nib from rusting.