The following is from Richard Binder's Reference Pages:
Waterman’s Ideal Fountain Pen. Imprinted on every pen L. E. Waterman produced from the 1880s into the middle of the 20th century, these words identify one of the most popular and collectible brands in history. But one model stands out among its siblings as perhaps the most popular Waterman: The Ideal Nº 52. (Revised February 19, 2010)
After devising and patenting a way to circumvent Walter Sheaffer’s lever-filler patent (by mounting the lever in a metal box instead of running its pivot pin through the body of the pen), Waterman began producing its own lever-filling pens in 1915. At that time the new lever-filling version of the Ideal Nº 12 received the added identifier PSF, meaning “Pocket (screw cap) Self Filling.” Two years later, when the company regularized its ailing Standard Numbering System, Waterman’s Ideal Nº 12PSF became Waterman’s Ideal Nº 52. In the newly ordered system, the units digit (2) meant that the pen carried a Nº 2 nib (as before), and the tens digit (5) identified a lever filler.
The 52 was a long-lived member of Waterman’s stable; even into the 1930s, when the pen world was dropping hard rubber like a hot potato as makers switched to the more durable and colorful celluloid, the company stuck with hard rubber for some of its pens, continuing to churn out the venerable hard rubber Nº 52 alongside the celluloid Nº 32 (which was later renumbered simply Nº 3).
There is also more wonderful information on David Nishimura's website Vintage Pens and there is a very good article on Waterman in general - here at Internet-Ink.co.uk.
This pen is the classic black chased hard rubber. It is 5-3/8" long capped and 6-3/4" long posted. The pen is outfitted with the proper #2 nib, which has a good bit of flex.
I actually bought this pen back in January and finally got around to inking it for the first time. I've been trying to resist the urge to ink a pen as soon as I acquire it, I've ended up with more than 10 pens inked, again.
Finally I reduced the number of inked pens to an acceptable level and decided to give this pen a whirl.
I am very glad that I did. Please note that I did not just fill this pen for this review. I've been using it for several weeks: writing letters, writing in my journal - it just happened that I used up all the ink as I was finishing this review.