8. Speed vs. Needle Penetration
A common misconception among artists is that simply increasing the speed of needle movement will improve its penetrability into the skin. However, as explored in this article, the primary resistance to penetration is offered by the uppermost layer of the epidermis, the stratum corneum, rather than factors often considered by artists.
Actual Function of Penetrability
Increasing the machine's speed does not necessarily translate to a more effective "punch" with each stroke. Instead, the penetrability power of the needle is largely a function of the machine's stroke height. If the total amplitude of the stroke wheel is greater (for example, 3.5 mm compared to 2.5 mm), the distance covered by the needle's movement is greater, thus providing more force upon impact with the skin.
However, this characteristic is not a property of the needle cartridge but of the machine's stroke wheel. This is why some machine manufacturers offer the option to change the stroke wheel manually. Most PMU machines include options for two types of stroke wheels: a short stroke (often around 2.0-2.5 mm) and a long stroke (often over 3.0 mm).
Therefore, assuming that increasing the machine's speed will enhance needle penetrability is a mistake. In fact, the opposite can be true. With increased needle speed, the artist may also need to move their hand faster, leading to poorer penetrability and potentially causing more unnecessary damage to the skin, especially if the needle "rips" the skin at some points.
Artists must understand that needle penetrability is influenced by multiple factors, including the machine's stroke height and how they handle the equipment during the procedure. Considering the complex interplay of these variables, reflective judgments about machine speed affecting penetrability should be made with caution.