What kinds of Parker 51 are there?
There are many factors that affects how sought after a Parker 51 is, from the year that they are made to the caps that they have, and the different colors they come in.
Here are some of the difference between Parker 51’s and my thoughts on them
1) Filling system: Vacumatic/Aerometric
Aerometric(1948 – 1969) is a sac pen with a squeeze mechanism, the sac is attached to the connector of the pen which is similar to the sac nipple in other vintage pens and is actuated and protected by a sac guard. The “Pli-Glass”(PVC) sac of the aerometrics is famous for being very long lasting, even now when i replace the sacs of aerometrics, i find that although they are stained, they are very much pliable and reusable. The modern replacement sac’s by David Nishimura of vintagepens are of a very similar(same?) material and is a little better in my opinion. Sometimes the sac turns to a milky white color, this process can be reversed by using a airdryer to blow on the sac, i think that the humidity in singapore causes moisture to be absorbed into the sac and by using a dryer, it can be returned to normal.
Filling with an aerometric is very simple, just squeeze the bar on the sac guard 4-6 times and the pen will be filled. The ink capacity is about 1ml(+-)
Vacumatic(1940-1948) is similar to a eyedropper with a pneumatic pump at the end of the barrel. The barrel of the pen acts as a reservior for ink which gives it a really large ink capacity of around 1.5ml(+-). The vacumatic system uses a expansion/contraction system with the help of a diaphragm. The pump at the back of the vacumatic barrel pushes(expansion) air out through the breather tube when the plunger is pressed and creates a vacuum(contraction) which sucks ink when the plunger is released.
The diaphragm is made of latex and the lifespan of the diaphragm varies from 5 years to 20 years, various sources point to things like letting ink dry in the diaphragm to using caustic ink as factors that might reduce the lifespan of the diaphragm. In my opinion , if the pen is filled with non-damaging ink and constantly used, than a decade lifespan is likely.
Filling with a vacumatic: depress the plunger until no bubbles are seen, ink capacity is about 1.5ml(+-).
Aerometric vs Vacumatic
Many people ask me which is better and in my opinion, both are the same and what you should get depends on your preference. here are some of the pointers i told them.
Changing inks: as with all vintage pens, changing the ink is often a pain as you cannot take out the sac to wash out the ink, however the aerometric is better at purging the ink as you simply have to keep depressing the bar with the hood under water. The vacumatic requires multiple depress of the plunger to purge the ink completely.
2) Types of Parker 51
There are many different types of Parker 51, here small list of them excluding experimental/demonstrator
Colors only in Vacumatics:
Buckskin/Nassau Green/Yellowstone Mustard Double Jewels (these colors are unique to vacumatics and mostly come in double jewel variants, very rare single jewel variants existed that were made for export sales)
Cordovan Brown/Dove Gray/Cedar Blue
all double jewels are vacumatics
Colors only in Aerometrics:
Flighters(stainless steel)/Signets(rolled gold)/presidential(9ct,14ct)
Plum/Cocoa/Forest Green/Blood Red
There is plenty of information and pictures on the above 2 sites and they will provide a very good read up on the history of the 51’s
Most of the caps that are sought after are unique to the vacumatics, the above link shows the various caps available.
The Parker 51 has many different kinds of nibs, from the almost never seen needlepoint to broad-stub.
however besides EF/F/M, the rest are pretty hard to find. The width of the nibs also vary from factory to factory and over the decades, might get worn down to a thicker width.
if there are any incorrect information, do send me a message!