Top of the Pipe Has Turned Blue

[Simonkenton]

Just hooked up the Oslo a few weeks ago, have burned it a dozen times. I noticed that the top of the stainless steel pipe, on the outside, has turned blue. About the top 18 inches, it is a pale blue, rather hard to notice.
Is this OK?

 

[TedyOH]

After reading this I would say yes?

(broken link removed)

 

[Jags]

Yep - what is even stranger is that the next time you look up, it will be shiny stainless again. Not sure why it does this as I can't imagine enough heat at the top of the pipe to discolor stainless, but something is. Its almost like some stack exhaust is condensing on the cold exterior pipe, or something. Not really the dark color of smoke condensing, but more along shades of blue.

 

[Dantheman300z]

Mine did and does the same. We have a strong east wind so it colors on the east side.

 

[Simonkenton]

OK thanks. I haven't overfired the stove so didn't know what to make of it.

 

[xman23]

I think it occurs more when the chimney is new. It comes and goes.