Some experimenting with materials has led to these.
First I used black India ink on rice paper. Then with acrylic medium I adhered the paper to wood panels. Then I painted over a bit with white acrylic ink. Lastly, a thin coat of spray varnish.
Acrylic ink is very nice! Thin like ink, highly pigmented and lightfast. However it is not waterproof and will smear if brushed over, therefore the spray varnish.