Army Painter recommend their strong tone Quickshade whenever you’re in doubt which one to use, and this is advice I’ve followed for pretty much everything I’ve painted.
Recently however I’ve started painting some 28mm WW2 Panzergrenadiers, and I wasn’t totally happy with the effect of the strong tone on the grey uniform. So I got some dark tone and did a test. Both these miniatures have simply had a flat grey coat applied to their uniforms:
The problem is that the strong tone is a brown pigment, but the dark is a black pigment. I think the black is a much nicer effect on a grey uniform. Army Painter do recommend dark tone for greys on their site, maybe I should have heeded that advice, but Quickshade is quite pricey, and I wanted to see if I could simply use strong for everything.
One issue I have found is that the dark tone isn’t great for shading flesh. The hands turn out OK, but the black shading on faces looks a little unnatural.
You can see this on the face of the mortar observer to the right. The black pigment doesn’t look right to shade Caucasian flesh. I’ve got around this by using the splash on method instead of dipping. This way you can avoid putting dark tone on the face and instead use a dot of strong tone.