Previously, they only sold writing instruments. But after the first Calamus series now comes the Aratrum Triangulus.
Let's take a look at this fountain pen with the Latin name.

The Aratrum company was known to stationery dealers, but not to customers. As a distributor, they were busy bringing well-known stationery brands to retailers. So that they could sell to you.

And in the time that they worked here, they naturally built up a great deal of knowledge. With the first Calamus fountain pen, they showed that they could also design their own pens. Now the second fountain pen, Triangulus, has come out. And Calamus is used as the brand name.

But what is important is that the brand is spelled Calamvs and the fountain pen is spelled Triangvlvs. Because that is the Roman spelling. The “v” was used for a “u”.
And calamus and triangulus are Roman terms.

And what makes the triangulus special is already clear from the name: it is triangular.

Unpacking the fountain pen

Fittingly, the Triangulus comes in triangular packaging. This is held closed magnetically.
The Triangulus itself is matt black. We have an anodized aluminium body here. The fountain pen is therefore still quite light. And stable.

As already mentioned, the Triangulus is triangular. With rounded edges. But you can't see at first glance where this pen has its cap. The body has the same diameter throughout. There is only one decoration with a few incisions. And the Aratrum logo.
But the opening is precisely in these incisions. When you unscrew the cap, the fountain pen splits right here. And it's really well done. Even with a magnifying glass, you can barely make out the cut.

Under the cap we have a short thread, a small grip section and a black Schmidt nib.

Writing the Calamus Triangulus

The fountain pen is well balanced in the hand. Incidentally, the cap cannot be placed on the back. But that shouldn't come as a surprise, as we have a continuous diameter here.
However, the grip section is not very large. With my large hands, I rest on the thread and the barrel.
Which doesn't bother me as much as I thought. The thread is not very noticeable and the difference between the grip section and the barrel is small enough. Especially as you grip on the flat areas.
Interestingly, you also have a guide through the corners. Also interesting.

The nib itself writes well, with feedback. Line variations can also be achieved with a little force.

My conclusion

The Triangulus is the second fountain pen. And Aratrum has already proven with the Calamus that they can do fountain pens. The Triangulus is also excellently crafted. They remain true to black. Even though the Calamus was briefly available in other colors. Matt black anodized aluminium seems to be popular here. And it feels good in the hand. The pen is well balanced.
I also like the concealed cut between the cap and barrel. I like these incisions in general. A very simple pen, with the incisions. It loosens it up and makes it interesting.
So it's definitely a fountain pen that I like.

One disadvantage, of course, is the slightly short grip section. This is because I rest on the thread and barrel. The thread is soft. You hardly notice it. The difference between barrel and grip section is also small enough. But it is strange. A larger grip section would certainly be better. But it works like this. It bothers me much less than I thought it would. And than it bothers me with other fountain pens with such a short grip section. But that is certainly also due to the slight difference. And the guidance provided by the special shape.

The nib can be seen as a negative. It is embossed with “Schmidt”. So it doesn't have its own nib embossing. But that is forgivable. Even if it would of course significantly enhance the value of the fountain pen. But it must also be said that this is not so cheap and would of course make the pen more expensive.
But let's wait and see whether there will be a third Calamus. And maybe something will change.

All in all, though, it's a good fountain pen. And I enjoy it. Even if the grip is unusual for me and not the prettiest. But it doesn't stop me from using the pen for long texts.

Technical data

Weight (empty)

Complete: 26 g
without cap: 20 g
Cap: 6 g


Cap: 13 mm
Barrel: 13 mm
Mouthpiece: 9.5 mm


closed: 13.3 cm
without cap: 12.7 cm
cap posted: – cm


Closure: Screwed
Type: Cartridge / Converter


There is also a video review of the Calamus Triangulus on my YouTube channel. Just take a look.


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Test Samples The product described here was provided to me by the manufacturer free of charge for this review. This was done without specifications and without influence on the article by the manufacturer. The opinion written here, whether positive or negative, reflects my own assessment.


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