I'm going to try elaborating my last post a bit in an effort to entice more artists and experts to the thread. 
People have talked a bit about Renaissance practices of painting and also about how changes in available technologies drive art production.
We've talked a bit about how part of the skill we appreciate in older paintings lies in the skill demonstrated by the artist (and even studio) in mixing the materials to make paint.
I think there is a big change in the early C20 in the availability of ready-mixed paint, and then a subsequent controversy about whether artists using this ready-mixed, ready-prepared paint were, actually, artists, and whether the artistry in art, it's validity as Art, as diminished by the incorporation of this non-individualised, non-bespoke, product into the finished piece.
I think part of what Damien Hirst's spot pictures is 'about' is this debate - old though it might be. Aren't they drawn from colour samples???
That's what I quite liked about the fluoro paint, and the spray-painted pictures. Is that part of what is going on with the use of thermochromic paint, too? Thermochromic paint sound as though you have to do things with the picture, too - like touch it! - or place it in non-temperature controlled environmnents - eek! - for it to react. And it has touches of the tackier end of rave culture, all of which sounds like a bit of an affront.
i really like George Shaw's paintings (he didn't win the turner Prize), who uses teeny, tiny brushes and the paint you use for model aircraft - hobbyists' paint - for his pictures.
The big essay on how technology drives changes in ideas about art is Walter Benjamin's "The Work of Art in the Age of Reproduction'. He is the person mist closely associated with the idea that photography brought about a radical shift in what we ask Art to do now. The availability of photography changed what we think of as the 'aura' of the work of Art.
The technological shifts I've listed above, around paint, are much smaller and just make minor changes in the production of Art - a sort of small skirmishing about at the boundaries - localised arguments about the placing of a fencepost here, or moving of the boundary about 10 ft outwards there - the Walter Benjamin essay suggests that the impact of photography was far, far greater, deeper and more profound.
Do people still agree with Walter Benjamin? Do they think photography was the big driver of change?
Surely the rise of the availability of tertiary education must play a part? And when did critical literature about Art start to have an impact? Indeed, when did it begin to be a thing? Is that also congruent with the impact of reproduction?