Has anyone used Vallejo Panzer colour series...
Vallejo Panzer Aces? I bought sets 3 & 4. Use them; like them.

Whether or not an individual painter will "like" them depends a lot on your style/technique. Personally I mix paints, so these are ideal.
Let's explain what they are NOT. They are not Triads.
You have a "base" and a "highlight" of each colour. If you applied the base, then the highlight, the figures wouldn't look good. I apply the base. Then I mix in a small amount of the highlight into the base and apply. Then some more of the highlight, etc.
As for accuracy of colours, I'm no expert but I think they look pretty good. Not that I've used them for "intended" purpose much yet, but I have used them.

First chap on the end with revolver. Shirt, jacket and trousers all Panzer Aces. Chap on the end leaning, jacket Panzer aces.

Jacket, helmet and cap - Panzer aces.
As you might guess, I recommend the paints.
