6 Mint Moller 85 chairs  

It would help a lot to see a...
It would help a lot to see a photo.

As you sanded, the wood got darker?
What kind of sandpaper did you use?
The results you seem to describe simply defy logic or my experience working wood... unless the sandpaper had been somehow contaminated.

Might
they have been lime waxed?

From N. O. Molller's catalog:
"Available in beech, oak, maple and teak."
That is for chair model 85, produced in 1981 with a paper cord seat. None of those sound like woods that would get really dark when oiled, though.
http://www.danish-design.com/designers/nom/catalogue/MOL85/

Oh wait...
What Robert UK said. Three of the woods in their description were offered in a soaped version and one with "white oil". Danish soap finish has white pigment in it, so maybe you have one of those and you sanded through it, though what you are describing still sounds much darker than any of those woods would be.

Sorry I cannot post any...
Sorry I cannot post any pictures. The wood all seems to be Teak and what I found strange was that it was ALL the same shade of light brown. I used ordinary sand paper down through 400 wet/dry and then Danish teak oil applied with 1000 steel wool and it went very dark, almost black What can I do now to bring it back to the same shade and color to match the res? The chairs LOOK JUST LIKE ones shown at this site http://www.danish-homestore.com/acatalog/info_23.html
Any suggestions to fix
Thanks Dave in Western Canada

Spanky may be on to something...
if you have worked with teak before you know there are some very drastic color variants. I've seen from red to very dark browns (almost black) depending on the grain pattern it may be a combination of two situations. 1) you sanded through the finish (as per spanky's comment) and 2) you managed to find a section of the teak wood that's darker than what your used to seeing in teak. if you just google the word teak you can see how many different colors the wood can be. all that being said i agree that without seeing photos of any kind its all just speculation...

Further to my last post. If...
Further to my last post. If you look at http://www.danish-homestore.com/ and the restoration pictures on the main page that is JUST like mine one rung looks like after sanding
???
Thanks Dave

The chair in that image has...
The chair in that image has a lot of grime worked into the wood grain.

"Sorry I cannot post any pictures"
Is this because you don't have a digital camera of any kind? Or because you aren't sure how to post photos? Just wondering. It's really hard for us to figure out what's going on without photos.

Are you saying that the wood...
Are you saying that the wood went black when you sanded, or only after you sanded, when you used steel wool and oil?
I would take the same steel wool and oil you used on the chair, and use it on a piece of different wood, and see if it causes the same darkening effect.
Woodworkers make black stain for wood by dissolving #0000 steel wool in vinegar and other acidic liquids. Steel wool can blacken things if an unwanted reaction is occurring, especially if the steel wool was already used to polish metal before it was used on the wood. Was the steel wool brand new when you used it?

No the steel wool made no...
No the steel wool made no difference. It went dark (almost black) like the pictures above after just sanding
Dave

I have pictures just do not...
I have pictures just do not seem to be able to post them??
in the past I had tried and had to have a web site?? or linked to a site where you could store pictures on line which I did not want to do.
Dave

Is there any chance the...
Is there any chance the chairs are teak stained oak? Looking at the catalogue of finishes provided by *spanky*, along with the OP's suggestion they are all so uniform in color they may have some factory finish on them.
Awhile back I attempted to sand and oil a few spots on my (what I thought was) teak credenza (Gunni Oman). I used 0000 steel wool and oil and the area I was working on became much darker as well, not black as the OP but definitely darker...and not in a good way.
I eventually realized it was not teak at all, but rather teak stained oak, although the side panels seem to be teak.
I hope I'm not confusing the matter more, but the OP's experience reminded me of me own...