They look great! Really nice

I would be interested to know your techniques and colours used if you are inclined to go into any detail
Thanks!

Main difference between imperial and chaos ships: imperial cruisers don't have a lot of plain surfaces - so they could be easily painted using drybrush. First imperials were coated with black spray, and then with dark brown spray. After that - heavy drybrush with some kind of Vallejo Olive Drab (color of WWII american greatcoats). Then much lighter drybrush with Iraqi Sand (one of my favourite colors ever

). Finished with light drybrush of Pale Sand - just to highlight the external details.
Drybrush on chaos cruisers gives dirty result - so I used another method. It's also easy, but requires some experience. After basecoating cruisers with black primer (and 15-20 min. to dry), I took medium grey spray and gave them some "very light touches". In effect it highlighted the edges and gave additional shape to plain surfaces. Then I used Adeptus Battlegrey to highlight the center of the prow and the control towers.
Metal parts were first painted with some kind of Vallejo blue-grey (bottle is so old, that the title is unreadable...), and edges highlighted with white (+ a small dot of the same blue-grey). Finishing touch for pseudo-metal (in fact, I can't call it a real NMM) is a watered down Burnt Umber to create shadows/reflections - use it carefully, and only on a non-highlighted parts.
For the "gold" I use a mix of Yanden Darksun with Burnt Umber, highlighted by Flat Yellow. Then I just paint some white (with a tiny amount of Flat Yellow) dots on the extreme edges - in case with flat surfaces, like a prow railing, I place these dots on the intersections.
It took about 4 hours to paint chaos ships, and about 2,5 hours for imperials.