Basically the Revell Aqua Color colours can be thinned with water, so that they can be sprayed. Thinning with Aqua Color Mix, however, has two advantages:
Firstly, the drying of the colour is delayed: this prevents a too quick drying of the colour in the spray gun & on the surface.
Secondly, this thinner optimises also the spray results on the model. When using the matt & silk-matt colour shades, Aqua Color Mix reduces the undesired edge-loss when applying the colour.