A fellow mu
sician asked recently for suggestions regarding the use of finger picks for slack key. He was essentially asking two questions. First, do finger picks create a “better” sound, as opposed to playing with bare fingers and, second, what are the best types of finger picks to use?
The choice of whether to use fingers picks boils down to personal preferences and, sometimes, to physical necessity. For musicians who play a lot, particularly on steel stringed guitars, there is the wear factor. Steel strings will gradually wear down the nails, creating grooves or uneven shapes in the nail. Some musicians deal with this by using professionally-applied nail fortification techniques, like silk wraps or gel wraps. Those approaches, while effective for maintaining nail strength, require periodic maintenance as the nails grow out. Also, the application process requires that the nail surface be filed to create better adhesion for the applied materials, and this thins the nail, so when the time comes to transition back to playing with normal fingernails, you have to wait for several months for nails of normal thickness to grow out again.
For us former or current 5-string banjo players, a plastic thumb pick and National metal fingerpicks are the popular choice, and that same combination can by used for slack key guitar. I’ve developed a preference, though, for the Pro-Pik metal fingerpicks, pictured above. Unlike the Nationals, Pro-Piks have an open pick blade, allowing contact between your fingertips and the strings. This provides for a more sensitive feel for the strings which, in turn, helps timing.
Another more recently developed fingerpick is the Alaska plastic pick (shown below). Unlike the metal fingerpicks, the Alaska pick extends 
from the top of the finger, rather than the bottom, so it more closely simulates the position of the natural nail. The grooves in the pick allow the front of the pick to fit underneath the fingernail, stabilizing the pick and effectively acting like an extended nail.
One of the main advantages in using fingerpicks is that they create more volume, which can come in handy when playing with a group of other musicians. Fingerpicks can take some getting use to, but they can serve a useful purpose in saving your nails and projecting in a crowd.