I was gathering up some spruce for feather sticks yesterday when I noticed that the inner bark was very stringy and thin. I figured it would make excellent tinder, and I was right. I noticed many of the thumb to wrist thick pieces of spruce I was finding had been saw cut, and my brother said they had been cut over ten years ago when a tree fell and was cut up to be removed. So this bark had been in constant contact with the ground and still had useable tinder in it. The bark easily separated...
Spruce bark tinder
Spruce bark tinder