A few months ago in my desk calendar was a wonderful illustration of a man making a shoe. Now I'm researching illustration for the American project I have come across the artist. Seounghyon Cho creates black and white images on location and later adds colour digitally.
This is the example I first saw and now I've seen his colour version of the image I've decided that I prefer this black and white location version.
The marks look slightly painted, slightly engraved. In fact, he uses encaustic wax - from what I understand, this involves using heated wax which is malleable while it is still hot. This can be made into an image and objects/materials can be added to the wax before it dries to create a collage.
An example of a wax image that has colour added to it. It looks like a silkscreen now.
When I looked up other images made by encaustic wax, it made me realise that I have used this technique before. While I was at primary school there was a Christmas fete at my brother's secondary school (which I would later attend) which had a stand with somebody with an iron and some wax sticks. You can see from the image above where the wax has been melted onto the iron then applied to the page. When the iron is removed it often leaves behind a veiny, leaf-like texture.