Finding out what my characters look like…

I’m writing a script for a graphic novel based on my books and that is weird enough, but part of the process of working with an artist is having to describe what my characters look like.
Anyone who has read any of my stuff will know that I don’t go into great detail on how my characters look physically. When I read a book, I like to create my own picture of how I see the people in it – that’s how I get attached to them so that’s how I like to write.
I know exactly who NG, LC and Hil are, how they behave, how they react to different situations, how they interact with others, what they drink, what they like and dislike, how good they are at poker. In the books, I’ve never fully described their physical appearance except for brief mentions of attributes that may be relevant to what they’re doing.
Working on a graphic novel is a whole new plate of bananas. So I have now written a full profile, including description, for each of them and talked in great detail through initial sketches with Rachel who is a great artist (and who is being very patient with me). It has been very strange. I feel as if I’ve been auditioning people for the parts… No, he needs to look younger; No, his hair needs to be shorter; Yes, he’s great. It’s all been very bizarre but I must say, lots of fun.