Draft page

A very brief survey of the key Parker 51 models from 1941 to the 1970s

51 Vacumatic

The Vacumatic filling system was developed by Parker in the early 1930s. Ink is drawn in to the pen by repeated pushing of a plunger at the end of the barrel.  This flexes a rubber diaphragm attached to the plunger with the partial vacuum drawing ink into the barrel.  Ink is held directly in the barrel - the pen does not have a conventional ink sac

Parker 51 Vacumatic in buckskin beige (also known as tan) with double jewels.  Vacumatic 51s - with the filler under the blind cap at the end of the barrel - were in production in the USA from 1941-48

Another Parker 51 Vacumatic in black with a coin silver cap and single jewel.  In production in the USA from 1941-48

First Year 51 Vacumatics produced in 1941 differed in some respects from the 1942-48 production.  The most obvious variations were that the barrel imprints were at the filler end rather than next to the clutch ring, and both jewels were metal rather than plastic

In 1947-48 Parker produced a demi-sized version of the 51 Vacumatic.  All parts except for the barrel and cap were identical to the full sized 51. An uncapped Demi is about 11.2cms long whereas the full sized 51 is 12.8cms

51 Aerometric

In 1948 Parker introduced the 51 Aerometric filler.  This filling system had a more conventional type of ink sac, made from pli-glass (PVC), within a metal sac protector

A 51 Aerometric Mk1 from around 1950 showing the long clip which was in use from 1948 to around 1951

In addition to the full size 51, Parker also produced a demi aerometric version.  This was identical to the larger pen, just proportionally smaller in all respects including the cap, and was in production until around 1960

A 51 Aerometric Mk1 from the mid 1950s showing the shorter clip.  Most 51s found in the UK are similar to this, with production running until probably at least the late 1960s

In 1961, Parker USA introduced a cartridge/converter version of the 51. This does not seem to have been a commercial success and was discontinued in 1963

The 51 Aerometric Mk2 introduced in the late 1960s featured a 61 style cap with plastic jewel, a slightly shorter barrel with flattened rather than rounded end amongst a number of other differences.  Importantly, the front shell and barrel were still made from lucite with the barrel threading being the same as on the Mk1

The mid 1970s saw the final version of the 51 Aerometric - the Mk3.  This had the later 61 cap with metal clip jewel. One important change was that Parker changed the type of plastic used for the shell and barrel to a softer version which is prone to shrinkage and also distortion from the pressure of the metal clutch inside the cap.  Threading on the front shell and barrel was also coarser than on the Mk1/Mk2, so parts from these models will not fit the Mk3

Later Parker models paying homage to the 51

Parker 51 Special Edition (2002)

Parker 51 (2021)

Original 51 (top)  Demi 51 (middle)  2021 51 (bottom)





This is only intended to be a very brief overview of the key immediate visual features of the various 51 models to help with a quick initial identification.  In describing the main aerometric design changes as Mk1, Mk2 and Mk3 I have opted to follow Andy Lambrou's terminology in Fountain Pens of the World.  Colour ranges, cap styles and the timing of design changes vary between Parker's factories in the USA, UK and elsewhere:  detailing these are way beyond the scope of this little summary