[this post continues in part from here]
From an email exchange with Sixty Grit yesterday:
Sixty: You may email me pictures of the railing wood and I might be able to see them better.
A close up of the end grain would be good, as will pictures of the long grain.
Me: [sends two photos]
Sixty: The piece that has been sanded looks like Douglas fir - straight grain, close growth rings - don't let a tree hugger see that - that is beautiful wood.
If you could sand whatever coating is on the end grain I would better be able to see what is going on there - just as there are standards for baluster spacing there are requirements for the type and quality of wood used in handrails - that looks like very high quality wood right there.
I think you're right about the bottom being Doug fir-I've worked with it before. The rail is more fine grained. Both woods are soft and can be scratched with a finger nail
Sixty: That looks like old growth vertical grain Doug fir. That is beautiful stuff, unavailable these days. The true tell is the aroma - since I can't see color too well - are you familiar with the distinctive smell of Douglas fir? I would say fill and envelope with sawdust and mail it to me, but we would both end up in jail if you did that. Perhaps a trip to the local big box wood store might be in order - they might have some Douglas fir in stock and you could compare and contrast.
As I say, that is high quality stuff right there - well worth refurbishing and keeping.
Me: The growth rings are much tighter in the railing wood.
Sixty: Indeed they are - I guestimate at least 30 rings per inch. Check the smell of both of them - if they smell the same then the railing was made out of old growth stock.
Me: They do smell the same.
Sixty: Well there you go - high grade vertical grain stock used for the railing itself, as required by code, lower grade used for the non-crucial application. I like it - sounds as if the mystery is solved. Well done!