A press-bar filler is an extremely simple mechanism, not much removed from a bulb or lever filler. A flexible reservoir is held inside a protective cylinder with a window cut in its side. One pokes a finger through the window to fill, striking not the side of the reservoir but rather a bar which compresses the reservoir more completely for a more efficient filling.
The earliest appearance of the press-bar filler was as the “sleeve” filler in the first age of fountain pens. In these, the window was cut directly in the barrel of the pen, and a sliding protective sleeve from which the style took its name rode along the outside of the barrel to prevent inadvertent pressing of the bar. Later versions, which appear to this day, see the whole barrel removed to access an inner protective shroud.
Thanks to the popularity of Parker’s “51”, one will see “Aerometric” used almost in preference of “press-bar filler”, in much the same way as one says “Band-Aid” or “Kleenex” in referring to the general sort of product. This is problematic, as “Aerometric” in Parker’s use indicates a couple of little extra internal complexities aimed at preventing leakage caused by changes in altitude (primarily, a breather tube with a relief hole well forward). Applying the brand-name to some other examples of the press-bar filler, which may or may not have a breather tube, is not unlike saying “Kleenex” of paper towel– it can be used in much the same way, but it’s really not the same thing.
In fillers of this sort with a breather tube, multiple presses on the bar will produce a more complete fill, as each press will evacuate air from the top of the sac more readily than ink from the bottom. In those without a breather, including converters, you may see slightly more ink in the sac after a second press, as the first will flood the feed, but any more work than that to fill them is wasted. In most pens made after 1949, it is wise after filling to gently press the bar with the point out of the ink to force three or four drops out of the pen and then release it so some air is taken in; this de-floods the feed, and reduces the likelihood of the pen dribbling on you.
Loading a Press Bar Filler Step by Step:
- Get a paper towel or other pen-wiper.
- Remove caps from pen and ink bottle.
- Expose filler, by either moving sleeve or removing barrel. Depending on the style and maker, the filler may have directions indicating how many times to press the bar.
- Immerse point in ink.
- Press the bar firmly, release, and pause for about three seconds.
- Repeat step five as many times as you find are required for the pen to stop blowing bubbles when you press. This may be as few as two or as many as eight times, regardless of what the side of the filler says.
- Remove pen from ink and
- in a pen made after 1940 or so, especially one with a hooded point, gently press the bar to express three or four drops of ink and then release it to take in some air, and then…
- wipe point and section (aren’t you glad you did step 1?), which in an older pen is all you really need to do
- Replace whichever cover conceals the press bar which was removed in step 3.
- Replace cap.