Hand Painted
How can I clean from nicotine. Age of 50-70 hand painted hanging glass?

I was recently cast light on some of the suspension. 50 and 70's era. People that I inherit from heavy smoking for many years and as a result of the lamp is coated. nicotine. I'm not sure what I can use that will not destroy the color. A kind of glorious hand painted roses on the worst of the lamp is to paint roses and then draw around the outside. Lamp is beautiful, but I fear indeed. Of messing up by cleaning it.

Pipe cleaner or alcohol. carfull that.