I actually like the Createx, so I'm not much help suggesting something new. However, I've had good luck spraying down a base coat of white, then overlaying with the yellow. That's a whole extra step, but one that has worked out for me. I'm just throwing that out there in case you don't get any other suggestions.

I do the same with the white. The I tersting thing is that. Have had white weep under the mask a few times so now I spray a thin color coat first and heat cure it and then spray my white coat. Then add the yellow layers. Haven't had a weeping issue since I did this. Could be a total coincidence but it has worked well so far. I tried Wicked yellow because they seem to have more pigment but it needed white base as well.

I documented a lot of my airbrushing in my JP restore thread.

I agree, yellow is a pain. I use Createx "Wicked" paints which are are designed to adhere to smooth surfaces (unlike Createx "Colors" which are basically for spraying T-shirts and other porous surfaces). But I had to start with an opaque white base coat before spraying yellow.

Thirding that. Had to do it on Crescendo repaint as well because it just looked "dingy" otherwise...it was transluscent enough to let the underlying color absorb some of the light, and putting the white underneath solved it for us.