No. 234 1/2 PL
The 234 1/2 is made of celluloid, and this particular one has the "platinum lined" (PL) design which I find mesmerizing! The model was made between 1936-38 and most probably for export because the German market was more fond of black pens.
This pen is from the personal collection of Paul Farrell, an enthusiastic collector of modern MB Pens (especially Writers Editions and 149’s) and a collector of exceptional vintage pens too!
To me, the flat tops were the most sophisticated design MB ever made. The 234 1/2 is the mid-sized model in the 23x range, with the 232 being the smallest and the 236 being the largest. Interestingly, there was also a 234 and 235 produced, but these are not so common to find. The 234 1/2 was probably the most popular variant in its series.
The "2" digit in its model signifies this pen was from the second-tier series. Catalogues explained that "the proven quality of this price range (2xx) created the worldwide reputation of the Montblanc brand". The "3" in the model number signifies that it was a piston filler. And, the "4 1/2" signifies its nib size.
The 234 1/2 came in a variety of colours, including black, azurite blue, malachite green, and platinum lined. It was also available with gold and silver overlay work. War time versions of the pen are available, with the steel nib and absence of cap bands. The 234 1/2 was also found in a luxury variant which had the tie clip and one thick cap band like the Meisterstück series instead of the "papyrus" clip and two thin cap bands that the typical 234 1/2 had. The papyrus clip on this pen is quite elegant, in my opinion, and it is period correct for the 1930s.
Unlike the star outline on the cap crown of the 33x pens, the 23x series have the full casein star in their crown.
The 234 1/2 had the telescopic piston which claimed double the ink capacity of ordinary pistons. Here we can see the original patent filed on 1st August 1939 by Rosler et al.
Normal pistons have a single-stage extension and retraction. However, the telescopic piston had a two-stage mechanism such that the second stage would collapse within the other first. This ingenious system meant that the piston itself took up almost half the space of a typical piston inside the barrel, thereby leaving all that extra space for more ink.
Unfortunately, it was not the most cost-efficient to produce and was also difficult to maintain, and so modern pens do not use it.
You can read more about the telescopic piston mechanism in this interview with master restorer Francis Goossens --> link.
For bibliography, see Resources page -->link