First-year Parker 51s: distinguishing features
Although test marketing began as early as 1939, the Parker 51 appears to have gone into full production only in 1941, the year of its formal introduction. Calling 1941 examples "first-year" is therefore entirely legitimate; surviving 51s that predate 1941 are exceedingly rare, and may appropriately be labelled "pre-production".
First-year 51s are identifiable by a number of distinctive features. Nearly all bear single-line imprints that run around the very end of the blind cap next to the tassie (first-year 51 were all double-jewel models, with a trim ring and jewel at the end of the barrel). A handful have been found, however, with imprints complete with 1941 date codes on the barrel right next to the clutch ring -- the standard location for 51 imprints from 1942 on.
Early examples had aluminum rather than pearlescent plastic jewels; although many collectors believe that first-year 51s without aluminum jewels are incorrect, this is demonstrably untrue. Since one also finds many examples with an aluminum barrel jewel and a plastic cap jewel (and never, it seems, the reverse), it seems as if Parker ran out of aluminum cap jewels first and saw no reason to waste the remaining barrel jewels. This is further supported by the fact that complete new old stock first-year blind cap assemblies turn up with some regularity in parts hoards.
The wartime constraints on raw materials also saw the original Speedline aluminum filler replaced with a plastic-plunger unit. When these changes took place is hard to say, but we have seen mint and boxed 1941-dated 51s with the plastic fillers. Our suspicion is that assembly of "1941" 51s continued into 1942 and perhaps even later, as Parker made do with what stocks it had amid material shortages, loss of workers to the military, and its own conversion to munitions production. 1942-dated Parkers are really quite scarce, and their pens of these early war years sometimes incorporate older material clearly making the best of what came to hand. It is not unusual to see 1942-dated Vacs and 51s with metal filler units, for example.
Some of the cap patterns introduced in 1941 continued in production thereafter. Others did not, such as the steel cap with the inset gold-filled band, similar to that of the later Flighter, but wider. The earlier caps can often be distinguished by the placement of imprints at the top rather than the bottom edge. Again, however, it is unclear when this change took place.
We have seen two types of 1941 demonstrators: one is so marked on the barrel, and has a transparent hood and a translucent red collector; the other has a transparent blind cap and hood, and an unmarked barrel. All examples seem to have black, not transparent, barrels.