The following information is provided by Uncle Bud
Tattoo needles do not dullen with age, but instead become sharper by the
repetitive honing motion they experience in the tattoo machine.
This happens because the metal of the sanitary tube rubs against the
needles, and the softer metal (the needles) will wear. The problem with
these sharpened needles is that they sharpen into flat razor-like edges,
and begin cutting the skin instead of piercing small holes.
Since a tattoo is created by the conical shape of the needle
transferring pigment into the skin with the aid of a wetting agent, the
needle's shape is as important as its sharpness. Pigment does not
transfer into the skin as efficiently when the shape is altered, and can
also lead to scarring.
Another problem with needles is the occurrence of burs or barbs when the
needles hit the side or bottom of the pigment caps.
While it is possible to use the same set of needles for more than eight
hours (on the same client, of course), correct needle configuration,
setup, and alignment of the needle and machine are very critical.