A tattoo gun, is a gun-shaped machine for creating a tattoo, i.e. marking skin with ink. Tattoo machines utilize electromagnetic coils in alternation to move the needle bar up and down, which drives the pigment into the skin.

The term tattoo gun is popular in Europe. In America, it is most often called a tattoo machine, and many a tattooist will become quite angry with you for using the term tattoo gun. In America it is simply considered naïve to call it a "gun" even though everyone knows exactly what is meant by the term "tattoo gun", the subsequent intimidation seems calculated to alienate non-conformity to the tattoo culture.

The basic machine was invented by Thomas Edison, and patented in the United States in 1876, as the autographic printer , which was intended as an engraving device. In 1891, Samuel O'Reilly found Edison's machine could be modified to introduce ink into skin, and patented the tube and needle system, which is still in use today. In fact, modern tattoo machines are essentially the same machine as the one O'Reilly invented.

Most tattoo machines can control needle depth to almost any degree and thanks to this control, tattooing has become a very precise art form, so precise that facial tattooing has become popular in the United States of America. The procedure is called dermapigmentation or "permanent cosmetics".

How it works

1. Power is introduced, and conducted via wires in two different directions: Through the coils to the adjustable contact screw (E), and through the frame (A) to the contact spring, (above C), via the armature spring (D).
2. Current, flowing between the contact screw and the contact spring, completes the circuit, causing:
3. The electromagnetic coils (B) to pull down on the armature bar (C), which causes:
4. The needle bar (F)to move down with it, the needles at the end of the needle bar penetrate the skin.
5. With the circuit at (2) broken, the armature spring (D) is free to exert its upward force again, causing the circuit to close with the contact made, again, at (2).

This process repeats several times a second, providing the artist with a means to penetrate the skin with ink without moving his hand.

The frame (A) must be non-conductive, and plastic bushings at the contact points are to be used to isolate the current from the frame. The capacitor (pink) regulates current flow. The needle tube (G) provides a grip for the artist's control, and a small reservoir at the tip for ink.

The needle(s) (small; not shown), are soldered to the needle bar (F). Finished needle bars are made by soldering small needles to the bars in varied numbers, depending on the desired coverage. For thicker lines and for shading in large areas, an appropriate sized "shader" needlebar is used. The tube's size, at the mouth, must be appropriate to accommodate the width of the needle bar.

Typical tattoo machines cost from $60 USD(Unimax, shown above)to around $350 (Cyberswash), though certain collectible machines can run into the thousands.