(This part of the forum really intimidates me, but I’ll just ask anyway, 'cause I’m curious.)
I’ve expanded my local whistling horde with a Feadóg nickle in D, which I really enjoy playing. It has a lovely sound and is a lot more co-operative than my Generation one. Seeing as I have played it rather a lot recently, it has gotten these black marks where my fingers normally rest. This IS normal, right? And can be cleaned away quite easily?
Those marks really creep me out, they look like eyes 
The eyes only watch. If you see teeth, put it down.
The same thing happened to me with mi Feadog Pro, so I guess it’s normal.
And it didn’t clean, it seems to be some kind of chemical reaction… but IMO it’s like the patina on the brass whistles, I like it 
That’s just the mark of a well-loved whistle.
When a whistle player sees that, he knows he’s looking at a whistle that gets frequent play.
–James
Upon close inspection of my nickel Feadog D, it seems that it’s actually still made out of brass but has a nickel coating on it. I don’t know if yours is the same whistle (mines just a cheapie) but perhaps you have just worn off the plating??
Mine is also one of the cheap ones, so it could of course be that it’s just got a thin layer of nickle on it… but I’m not about to poke around on her with a knife to see if it comes off! The “eye effect” does seem like a chemical reaction thing.
Ok, so the eyes stay. Uäh. (But no teeth yet phew)
Thanks for the answers
Mine hasn’t begun to wear or flake off yet but it’s easy to see, when the light is just right, that it’s brass. If you shine some light down the tube, you can see the brass color through the tone holes. I also took the fipple off for a quick tweak when I first bought it and the inside of the whistle was unfinished towards the top, showing brass rather than the nickle.
Nickel plating is also as chrome plating. Good chrome plating has a coating of copper applied before the chrome. For it to be a nickel alloy the price would go up. Copeland makes a nickel alloy whistle.
FWIW, stainless steel is an alloy with nickel.