I'm new to the whole "drybrushing" thing. Can you explain more about how you applied the Humbrol 70 and 85 after painting them with Humbrol 56?
For my drybrushing I take a n°6 or 8 wide brush. First I apply the n°70, I dip barely the brush in the paint and wipe off the excess on a paper towel. The brush must be almost..dry... Then I apply it here and there over the part. I do the same with the n°85 (but much lightly than the 70 color) Well it's not that easy to explain with words, moreover when it's not your native language I hope my "explanations" '^^ will help you a little.