I just got a set of Pyramid Gold flats in the mail and I am very impressed with how they sound and feel. After playing them for the first time though I noticed black greasy **** on my fingers. What is that?
That's just grease and will go away after wiping them down a few times. Those are some of my favorite strings. Very unique in feel and sound. I always have a P bass strung up with those strings. Great vintage tone for rock, r&b, funk, pop.
A fellow from Pyramid once told me to use a cotton cloth slightly dampend with lighter fluid to remove the manufacturing oil. Then wipe the strings with a dry cotton cloth. Once that's done that will be all you need to do.