There are three main methods to mixing pigment powders. One wrong, one nearly right and one correct method.
The first is the wrong way, but SO many people use this method!
They open the clear matte, pour in the powder pigment, give it a mix, pour into gun and spray!
Wrong, wrong, wrong!
The second method, shown below;
It's pretty similar to the first method, except you do this 24 hours BEFORE you spray. Helps the pigment disperse into the matte clear. Helps eliminate patchyness, stripes and 'bits'.
The third and proper way;
Add the pigment to a carrier (in this case our pigment blend). Shake, let this selttle for minimum 24hours. On the day of spraying, give it a shake and pour into the clear matte. then mix this and you have your colour.
This disperses the powder MUCH better, gives a smooth colour throughout.