Smoke is not colored by additives. It make have diffent shades depending upon the content. For example a hotter ember will have a grey white smoke, while a slower colder ember may be black and dark. If it has lots of tar the smoke could be yellow and thick, or if its less moist it could be thin and whispy.
What gives smoke color?
The color of the smoke depends on the material that is burning. Natural materials such as unfinished wood will change to tan or brown colored smoke, whereas plastics and painted surfaces appear to be grey in color. However, black smoke can appear grey when it is mixed with moisture from other heated materials.