The tip of the ballpoint pen is full and clean, without deformation, and no stains. It fits with the pen barrel loosely and moderately, and cannot move with the pen core. When the pen tip diameter is less than or equal to 2.5mm, the length of the pen core exposed from the barrel should be less than 2mm; if the pen tip diameter is greater than 2.5mm, the length of the pen exposed from the barrel should be greater than 3mm. Whether it is smooth when pulling out the cap and whether there is friction obstruction to other parts of the ballpoint pen. If the ballpoint pen is pressed, the switch between pressing and reset is flexible, and the ball is not exposed when resetting.
The size of the ball diameter determines the thickness of the writing lines. The diameter of the common ball is 0.5~1.0mm (the pen body or ballpoint pen core of the product is often marked). The ink of the ballpoint pen is specially made, mainly mixed with pigments, solvents and viscosity adjusters. Good ink has the advantages of light fastness, water resistance, and non-bleeding. Experiment by drawing circles on the paper, writing fluently, evenly strokes, consistent color depth, and no pitting or broken lines.
Generally, ballpoint pens are designed with plastic sleeves or concave-convex patterns on the barrel. One is to increase the friction between the hand and the ballpoint pen, and the other is to prevent finger deformation when writing for a long time. It is a good ballpoint pen that feels comfortable and doesn’t feel tired when writing for a long time.