Part painting, part photograph: it's a hand-tinted print
When I decided to hand-tint blueprints for the Hong Kong book, I knew that there would be some puzzled reactions: is it a painting or a photo, or something in between? For centuries, hand-tinting has been a common way to enhance black-and-white photographs, woodblock prints, and etchings.
After weeks of experimentation, I found that blueprinting for less time (underexposing them in the sun) gave me more freedom when tinting. Instead of simply coloring the prints, I enhanced them, expanded their borders, and blurred distracting details. Beginning with blue adds a brilliance of color straight away, whereas black or sepia subdue it.
When I paint the photo-sensitive chemicals before exposure, I selectively apply them with a brush. Once it's hand-tinted afterwards, it's actually a twice-painted print.
For another perspective, Jeane Vogel talks about hand-altered photographs and their ambiguous position between painting and photography here.