A Parker Duofold fountain pen with a nib having a significant amount of iridium can only be found in a narrow range of dates. The Duofold, itself, was introduced in 1921 and manufactured until about 1932, when it was relegated to a less prestigious line and it's shape and nib changed. From the article excerpted below:
This allows a three-year window for a pen that can be described as a "Parker Duofold with an iridium nib" as Sherlock describes the instrument used to write his name on the envelope at the beginning of "The Great Game."
Where's the Iridium?
(Previously published in The PENnant Vol. XIII, No. 2)
"There is no iridium in the iridium", Kurt Montgomery said to me as we looked over the print out from the EDAX. We were looking at the material analysis of a Waterman's Green #7 nib tip from the 1930's.
Most pens today (and in the past) use an alloy of materials for the hard surface tipping on the end of the nib. This alloy is composed of a number of elements. If iridium is present at all, it is rarely the predominate element.
The word iridium has become synonymous with tipping, in much the same way that Kleenex is synonymous with tissue paper. We all know what we mean when we say iridium. It is the little bit of hard white metal that is attached to the gold points of a fountain pen.
My first inkling of the relative absence of iridium occurred in 1991 when I took in a piece of tipping from a 1918 Waterman's N.Y. Ideal #2 nib to the Pacific Spectrographic Laboratory in Los Angeles for analysis. I got to watch as they put my pinhead sized piece of metal in a ten-foot long machine. Using a burst of energy, they vaporized the sample, turning in into a tiny cloud inside a chamber. They then read a spectrum of light as it passed through the gasses. The results* were:
I have learned, by examining the margin between the tipping and the gold of the nib, that all early points, those made before the 1940's were made by attaching rough chunks of unshaped tipping to the end of the nib. I could see a rough margin between the materials, which indicated the crudeness of the material that was placed on the end. This margin can be seen using a 10-power loupe. In the early days of nib making, the material used was unrefined ore, crushed to size and applied onto the tip of the un-slit nib. It is for this reason that there was a fair amount of difference in the tipping material, depending on where on the earth it came from.
Melting and alloying tipping material posed insurmountable problems for the earliest pen makers. For this reason, many of the earlier tips exhibit flaws that can be seen running from one side of the points through to the opposite tine tip. A fine uniform material was just not available.
Last year, while making electron microscope photos of contemporary Parker Duofold nibs with Kurt Montgomery, he explained that a material analysis was also possible with EDS, energy dispersive spectroscopy. By directing a beam of electrons at the metal, the composition of the material could be analyzed.
The earliest Parker nib tipping that we looked at was a Lucky curve (lazy "S") from the mid-teens. Its analysis* shows similarities to that of the first one that I analyzed, the Waterman's from about the same period, except that this time there was more osmium than iridium:
We looked at a 1920's Parker Duofold Sr. and found that the material was from different metal groups, a sure indication of an engineered alloy. Notice that when the iridium disappears, the tungsten shows up. This tip still shows the rough margins indicative of fractured tipping material, not the uniform pellets that came in during the next decade.
A second 1920's Duofold revealed the following different engineered tipping composition. Tantalum is very resistant to acid attack, so it could be in there to hold up against the ink.:
(It is possible that in this sample, the machine read some of the gold nib material, which showed up as gold and copper.) But even so, when factoring this out, the other materials still had a very different composition from the other Duofold that we looked at. Where was the iridium? Parker Duofold nibs of the 1920's were the gold standard of fine tips. I draw two conclusions from this analysis: Parker was still experimenting with their alloy, and iridium was not a necessary ingredient.
We can date the senior Duofold size Lucky Curve nib fairly accurately to the period when Parker first came out with the Jade Plastic pen around 1924. Its composition shows no iridium at all:
A later Duofold pen, with the "Made in USA" imprint from around 1929 shows a very different makeup. We are back to the platinum group of metals characteristic of earlier "as found" material tips:
A 1940's Duofold shows a heavy reliance on tungsten. Because it does not occur in nature with the Platinum group this is a designed material tip (3):
I am certain that tipping was used in some sort of raw form on the earliest nibs. I have come to believe that sometime around the late teens, metallurgists were able to refine the ores and alloy them into more desirable and/or less expensive metals. It seems that a great deal of experimentation was going on during this period in order to find a superior material. And finally, the modern era of tipping emerged with the pelletized tipping, which I have first seen on the Parker 51. All gold nibs made today use regular spherical forms to provide the wearing hard surface. A future article will look into the materials of contemporary tipping. (Of the few that I have looked at so far, none contain iridium)
*Please note that because of averaging, or because only the elements that we were looking for, show up, the numbers often do not add up to 100%.