How is a rollerball pen made?

The rollerball pen is a fairly recent invention: it was first created in Japan between the 1960s and 1970s, but it never became popular in the country of origin. It conquered instead the American market and recently the European one, in particular for reasons related to lifestyle. In a country like the United States, characterized by a very practical and frenetic lifestyle, the roller was immediately successful because it allows a fluid and very flowing writing, similar to that of a fountain pen (they both use water-based inks), but more practical. It is composed of: Cap, Body, Writing section and Refill. One of the features that allows you to immediately distinguish a rollerball from a ballpoint pen is the cap. In fact, the cap of the roller, as in the fountain pen, always covers the writing unit (to avoid drying of the tip), unlike the ballpoint pen, which has the cap at the top that allows the refill tip to come out through pressure or screwing. In this case, the ink is water-based, more fluid and flowing. It allows you to write with very accentuated inclinations of the hand.