White ink is predominantly used as a highlight or accent color to further enhance the natural variation between light and dark shading and line work applications.
There are more tattoos that use white ink as a core component of the design (and purely white ink tattoos) however they tend to need more touch ups and refreshing.
Due to this, and the cost component, many black and white tattoos – such as the Punisher’s white skull on black ink – use negative space to create the contrast instead