4. technical details of the machines

Stroke length (Stroke Length)

The stroke length or stroke on PMU machines refers to the distance the needle travels during a working cycle.

Specifically, this is:

• The distance covered by the needle during a complete up and down movement.

• For rotary machines, this corresponds to the distance required for one complete rotation of the motor. The stroke length of permanent make-up (PMU) and tattoo machines has a significant influence on the result and the application.

Influence of the stroke length

• Penetration depth: A longer stroke length means that the needle penetrates deeper into the skin. This is particularly relevant for the difference between PMU and tattoos:

  - PMU generally uses shorter stroke lengths, as the pigments can only be used up to

    to the basement membrane (area between the first and second skin layer)  

    are to be introduced.

  - Tattoos use longer stroke lengths to apply the color deeper and more permanently in

     the skin.

• Application of forceThe stroke also influences the force with which the needle hits the skin:

  - Longer strokes generate more momentum and have a longer lever,

    more torque and thus a stronger impact and more power. 

    Power transmission.

  - Shorter strokes work more gently and are therefore suitable for more sensitive

    Skin areas suitable.

• Speed: The stroke length affects the working speed:

  - Shorter strokes enable faster needle movements.

  - Longer strokes require more time per up and down movement.

Areas of application

The choice of stroke length depends on the desired result and the technique.

Short strokes (1.8 - 2.5 mm)

Short strokes on permanent make-up (PMU) machines, typically between 1.5 mm and 2.5 mm, are particularly suitable for specific permanent make-up techniques and applications. This stroke length offers a smoother and more precise needle movement, which is ideal for detailed work and sensitive skin.

Suitable techniques for short strokes:

• Soft shading, transitions and precise lines.

• Multiple passes without putting too much strain on the skin.

- Work on sensitive skin areas, especially the face.

Restrictions:

Short strokes are less suitable for drawing strong, defined lines in a single pass. The lower force is often not sufficient to use larger needle groupings effectively. Longer strokes are more suitable for work that requires more pigment in a single pass.

Medium strokes (2.5 - 3.5 mm)

Medium strokes, typically around 3.5 mm, are a versatile choice for various permanent make-up (PMU) techniques. This stroke length offers a balanced combination of power and precision that is ideal for many PMU applications.

Suitable techniques for medium strokes:

• Shading with pixel effects, color fillings, line work with smaller groups of needles.

- Shades and color gradients.

Restrictions:

With larger needle groupings, the force may not be sufficient to achieve optimum results. For extremely fine and detailed work, shorter strokes may be more precise and efficient.

Long strokes (+ 4.0 mm)

Long strokes with PMU and tattoo machines are suitable for certain techniques and applications.

Suitable techniques for long strokes:

- Strong line work.

- Large needle groupings and color saturation.

- Working on thicker skin.

Restrictions:

Long strokes are less suitable for fine detail work and shading. The increased force can lead to overworking of the skin for inexperienced tattooists. They are generally too strong for permanent make-up in the facial area.