hiya working with a team as the artist for new comic, the comic is a noir horror based on the first and only police force since an apocalyptic effect a hundred years before. For the colouring we were going for a simular look to the blacksad graphic novels (below). These were coloured using watercolours, however due to time and deadlines. We don't have the time to colour the panels with paint. Does anyone know how to produce a similar effect using photoshop cs2?

Painter is better for that kind of thing but I have some suggestions you could try. First, a custom brush with ragged edges and opacity. Also maybe try setting the brush smoothing off but have wet turned on (in the brush options palette). Second maybe to add a monochromatic noise with a low opacity or a blending mode. You could try creating a paper texture and use the texturize filter for that too. When the painting is done use desaturate under the IMAGE option. If you hit Cntrl+shift+F on a pc directly after using desaturate (or any filter or other image adjustment command) you should get a box that will pop up with blending and opacity options that can be applied to the desaturation command. Or duplicate that layer, desaturate and adjust opacity/blending that way. Hope that helps.

you could also try posterization of a new layer and adjust the opacity/blending too.

Normally, when I'm painting digitally, I use the oil technique of starting from a mid tone, and then working the lights and darks from that.

If I were to try and give a watercolour feel, I'd start with white and work light to dark, because that's how watercolours work.

I'd also suggest doing a fair bit of the painting with light washes, and having the brush set to "multiply", to emulate the transparent and additive effect that watercolours have.

Perhaps it might be an idea to make a palette of some standard colours, with variations of them fading to white, to give you something similar in feel to diluting the paints with water.