Dating parker pens
Some of the earlier Vacumatics actually had a "reversible" point; you could turn the pen upside down and write (with the feed facing up) to get a finer line.Although the Vacumatic's filler plunger may look superficially like an earlier button filler pen, the filling process is actually quite different.Of course, amid all this praise, we must also acknowledge the dirty little secret of the Vacumatic: it was anything but the "first sacless pen" it was touted to be.For one thing, manufacturers such as Onoto (with its plunger filler), Pelikan (with its piston-filled 100) and Conklin (with the piston-operated Nozac) had already come to market with truly sacless designs, and in any case Parker publicists were really splitting hairs in refusing to call the Vac's rubber diaphragm a "sac" (a fact that Sheaffer publicists were happy to point out in preferring the virtues of their Onoto-stye plunger filler).The second generation pens (1937-1941) became more diverse in style.Wider cap bands came into use, and in later examples the simple feather-arrow clip was replaced by a more ornate clip bearing the name "PARKER" and (for more expensive models) a blue diamond mark at the summit.The Vacumatic filler unit evolved over time; originally, it was made largely of aluminum, and was designed to stow away in the down position (with its internal coil spring fully tensed).
The new Vacumatics looked quite modern compared to the Duofold; although Parker had updated the Duofold with new colors and a more streamlined appearance, it still had the ball-end washer clip and black ends of the 1921 model.
Parker Duofolds of the later 1930s often had Vacumatic fillers, like this example that boasts the Speedline filler button.
The design changed more radically in the 1940s, when the second world war made more pressing demands on aluminum; the third generation plastic fillers came into use in the 1940s.
It takes around 5-10 taps of the plunger to fill the pen completely.
The breather tube allowed the air pressure inside and outside the barrel to be more quickly equalized, which in theory meant that Vacumatics would behave better than sac pens if you took them up in airplanes (even some sac-fill pens, such as the Eversharp Skyline, would later adopt breather tubes for similar reasons).