Boneset is Eupatorium perfoliatum, which is used for very different things than comfrey is. Eupatorium Perfoliatum is sort of like echinacea in terms of immune action, except that it works even if you don't take it at the initial onset of a cold. Do some research on it, it's an absolutely amazing immune stimulant and there's some good studies on how it works and on which immune component.

Comfrey is more of a wound-healer. There was a poorly designed study in the 90's that showed that supposedly it can lead to liver cancer or some other serious condition (I don't recall which one), which is why people are afraid to take it internally. I think that study has been debunked.

Sorry I don't have more info, I don't recall all the details.

I got a lot of my info on boneset from David Hoffman's books such as Holistic Herbal and Medical Herbalism: The Science Principles and Practices Of Herbal Medicine, and from several of Stephen Buhner's books. It's been very, very good for me when I have flu and colds, and has been helpful with some of my Lyme Disease relapses (which might be due to a coinfection and not just Lyme).

Comfrey is in one of Stephen Buhner's formulas, a recipe for stomach ulcer, which is described more in his book Herbal Antibiotics.

Speaking of which, there's a lot of good info in that book about topical antibacterials, though killing bacteria is not necessarily the only thing that'll address tattoo issues (since tattoo healing isn't all that hard for a healthy person, and there's the non-medical concern about not drawing ink out of the fresh 'wound'). Speaking of healthy tattoo healing, stay away from alcohol, that's one I've heard quite often in light of this subject.

One thing I've heard in the tattoo industry is that certain inks will be pulled out by petroleum-based ointments, etc, but I know (I used to make body piercing jewelry so I was marginally involved in the business) that people in that industry don't always do good research before making a proclamation like that. It's possible that what affects ink fading is more about the base of the ointment rather than the herbs in it.

Personally, I haven't seen any problems with tattoos fading no matter what I've done (my color ones are 11 years old and BRIGHT, and I get comments on them every day that they're visible, and everyone, including other experienced tattoo afficionados, is amazed at how old they are for the fresh-looking color), so I think it has more to do with the artist, ink type, and skin type, than it does with aftercare.