Color Pigment/dye affect plastic softness?

Good question Pirvan; I've been wondering something similar myself: 

I have three spools of ABS from the same supplier - black, red, and white.  The black filament is fantastic, and I get excellent prints from it; no warping, it sticks well to the bed, and flows very consistently giving very smooth and even prints.  The red is very good, but comes out more pinkish, and has occasional problems with warping and sticking.  The white is fair to poor:  doesn't stick as well (I occasionally have to use a glue stick), is prone to warping as it cools, exhibits noticeable banding, and although the raw dimension is fairly constant doesn't extrude consistently - I'm frequently adjusting the extrusion multiplier in the filament profile of Slic3r.  (I do have a slightly different Slic3r profile for each color)

I'm thinking that whatever colorant was used, has some effect on the thermal properties of the ABS during printing...and as you suggest, may also affect the final hardness of the completed print.

Ok, Atron, I would caution against applying your logic to our case.

The emissivity of an object is often related to color, but a couple things (1) Darker object will cool actually *faster* than a light object. The confusion lies in that a darker object in sunlight might cool slower, because it's being heated by the sun.  Objects emit and absorb light. This is usually fairly close in value, exceptions arise that have very different emissivities vs absorption. 

Moreover, I doubt radiation is the dominant factor in our system. It might be substantially meaningful, because we are talking about 230C, but it is not likely to be dominant for at least part of the cooling. However I am speculating without looking at the numbers whether radiation matters much at 230 celsius.  This is based on my limited experience, and not expert knowledge

As a whole this thread is totally pertinent and I wish I knew more to contribute. Colorants and plastic mixes are likely to matter a lot. Remember ABS is a not entirely standardized mix of plastic and (though likely not within manufacturers, merely between) they are likely to have subtlety different mixes of plastic. I feel like by the time I print a few prints on a roll though I can tell I need to up a few degrees or go down a few degrees on the temp, since the plastic seems slightly different. this is not a science though I wish I could do it more effectively.

Also, there are some rare brands are *absolutely* not plain ABS. Afinia filament, for example, prints well at 260celsius. This is HOT, compared to most brands. I had trouble vapor smoothing a gnome I printed with that filament, and I speculated that maybe it's ABS-PC, merely because the plastic wasn't melting well in acetone and 260C would be reasonable for a ABS-PC mix.  *speculating.*   Overall i loved the afinia brand but it was too expensive ($50/700g) for me to use much.