Okay so these results MAY be the hypothesis buster (that there is something else other than colouring that is affecting the paints - i.e. a chemical reaction that isn't related to the colouring chemicals)
Coca Cola - Original vs Blood Red = Coca Red
Being a certainly darker and 'reddish' drink than the Creaming Soda - which was greenish-yellow - the first coat of red was MUCH more 'successful' in that it covered all the black areas without too much of the blacks showing underneath. Also there's less 'pooling' of paint across the smoother surfaces. Which is a definite bonus for painters since, even diluting the paint with water with the wrong ratio (i.e. too much water) would result in the pigments clumping together with a tonnage of clear dilute areas.
In any case, Coca Cola beats the Creaming Soda in several areas;
1. the paint was very 'stable' - no pigment haywire syndrome and dissipating all over the place
2. the paint was thinned but it was not diluted in consitency (perhaps due to the darkening/addition of the colouring?)
3. the paint did not end up drying as a sticky layer like the Creaming Soda
Some areas which it failed to serve as the most ideal paint additive;
1. it still makes your miniatures smell like coca cola
2. unlike the Creaming Yellow, Coca Red dried up faster. (hmmm interesting) - this is not a serious defect as some people prefer their paint to dry faster; however, some people may want to use wet layering or blending techniques which requires the paint to stay wet as long as possible... but in that case, you'll be having to add another solution to keep the paint wet longer anyway, so this is no BIG defect.
Chemistry Questions still left unanswered and more added;
1. What on earth is going on whenever I add a soda drink to paint?
2. Why did the Creaming Soda act the way it did with pigments separating all over the place? (Is it like the fact that the carbonated water can be used for removing stains? - and I'm sure this is as generic as it gets in terms of chemistry stuff)
3. Why did Coca Cola then work better? Was it really the colouring?
I think ultimately colouring is the key here... but it tends to work well for other colours too...
So maybe the colouring does help out the colour it is based on (Coca cola + Red) (Creaming Soda + Yellow) ... but when it comes to adding other colours, it only works as a non-water based diluting agent?
But that still doesnt' explain how with other colours the paint managed to keep a better 'coverage' - even blue was used with creaming soda;
Results (Blue + Creaming Soda);
Green was not the resulting colour - it stayed blue
Paint was much easier to work with (I think this may be psychological; since paint brushes are easy to ruin with additives, I'm being more careful with how much paint and how much 'soda' I NEEDED ... where as with water, it was kind of dip-and-wipe to get the amount of water I WANTED).
In anycase, much better consistency (but compared with water it wasn't a JUMP of an advantage, it was just able to cover much better.)
Resulting hypothesis;
colouring adds more pigments no matter what to the colour - therefore adding to consistency
I'll keep posting with updates and such; if you feel like it, just say something. (like 'oh you're so stupid with this, this isn't even a chemistry experiment you twat!' *throws pippet*). But you know, be nice. Try to keep it 'chemical' -_-
sj