adjusting white balance

[Newmarket2]

I was in a gallery which was nice enough to let me take a photo of a large oil painting.
But, although I tried several WB settings on my D300, nothing seemed to work.
I came home and there tried to make appropriate adjustments using TINT but it just isn't working.
I think the gallery would tell me the specifics of the lighting system they use, and then I should be able to look at the specs of those lights to find out what they are.
But, what are the specs I'm looking for? Just the temperature in Kelvin? Or more than that?

 

[clee01l]

One of the problems with shooting JPEG is that the WB gets "baked in". Now you have very little latitude for correcting. The best you can donoe is touse the 'eye dropper' tool to pick a white or neutral color from the image and let LR make the determination.