The John Blair’s Nosak fountain pen is one of the more unique designs I have come across. Virtually all self filling fountain pens have seals or sacs that will eventually need to be replaced. The only ones I can think of that do not have seals or sacs are the Parker 61 capillary filler, and the Blair’s Nosak Self Filling pen. (I made a clear acrylic version out of curiosity. It is demonstrated at the bottom of the page)
The design was protected by US Patent 1,006,050 filed November 1910, issued October 17, 1911. Ads, however, mostly date from early 1907 through 1909. I have owned two examples of this pen, both imprinted as “PAT’D” but not listing patent number or date. What is really amazing is how simple it is. In a way, it has no moving parts. Well, the cap is the moving part, but isn’t it always?
“The holder is filled by the suction of this pen cap”
The rear end plug of the barrel is loosened so it is no longer air tight. The cap is posted deeply on the narrowed, cylindrical non-tapering, back end of the pen. There is a side hole on the cap. You cover the hole with your finger and slide the cap back, creating suction on the end of the barrel and drawing ink in through the nib and feed. Release you finger and push cap back down. Repeat. Ink is drawn into the barrel with each upstroke. It only takes two or three pulls. When done, screw the end plug back down for an air tight seal.
It actually works.
A portion of the patent reads:
To fill the pen, the lower end thereof is dipped into an ink well, plug 19 is slackened, and cap 23 is projected over the upper end of the barrel. The cap is now slowly reciprocated along the barrel a few times, vent 24: being closed by the thumb during the upstroke and opened during the downstroke. In this way the ink will be pumped into chamber 22 and will be held against overflowing by disk 20. That is to say, when the pumping operation is unduly prolonged, the flow of the ink will be checked by disk 20, so that it cannot enter chamber 21 in any appreciable quantity or ooze out around plug 19. Any objectionable overflow of ink is thus prevented and cleanliness is insured.