Experts claim that the 138 was made for a very few years - between 1938/9 and 1941/2, while the rest of the 13x series continued to sell through the latter part of the 40's. However, some claim to have found 138s with features from later years even up to the 50s. These pens may have simply been old stock reassembled by retailers with newer parts, but it is uncertain.
This 138 is a little brother to the L 139 (link for review). However, the 139 was very deliberately positioned as the "luxury format" of the 13x series. Catalogues show that when the 139 was priced at 45 Reichsmark the 138 was priced much lower at 31.5 Reichsmark.
While the 139 enjoys legendary status in the vintage MB community, the truly discerning curator knows that the 138 is, in fact, rarer and - in my humble opinion - more significant as a collectable star!
One key characteristic that differentiates the 138 from the 139 is the cap ring. The 138 has a single thick cap ring, while the 139 has the iconic silver rings.
In terms of size, the 138 is pretty much the same length as the 139 though the nib on the 139 is larger. The 138 measures around 15.7 cm posted. It is a large pen without any doubt.
This pen is from the personal collection of Stilusaurea. Read more about some beautiful vintage MBs in their collection --> link.
The 138 is found in many variations in terms of the materials used for cap tops and barrel bottoms, clips, nib materials, ink window length, and imprints. This particular 138 under review has all my favourite features - the long ink window, tie clip, and steel alloy nib. The 138 nib - whether gold, palladium, or steel alloy - was a size 245, which is smaller than the larger 250 size found on the 139.
Most 138s are found with steel alloy nibs because they were produced during World War II when gold was declared a critical resource and not allowable for use in pen nibs. The few gold nibs, and even palladium nibs, that are found on the 138 must be from earlier years of production. The 138 steel alloy nibs are known to have distinct flexibility that is quite appreciated by collectors. Based on pictures of some steel alloy 138 nibs, we can see that they had a two-tone appearance - maybe they were gold plated or treated in some way? However, it is difficult to find such two-toned nibs today as the plating or treatment seems to have worn out on most of them over time.
One of the unique selling points of the 13x series was its telescopic piston which claimed to allow 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 iterations of the 14x do not use it.
You can read more about the telescopic piston mechanism in this interview with master restorer Francis Goossens --> link.
Advertisements during the post-war period when MB was still to start full production in Germany.
Fountain Pens: Vintage and Modern by Andreas Lambrou
For bibliography, see Resources page -->link