Donor computers are acquired by gift or by auction. The machine is completely disassembled and the main circuitboard is stripped of it's components by desoldering each one.
It's scrubbed, burnished and photographed, and then the copper circuits on both sides of of the board are traced, much in the same way as when they were originally laid down by the designer.
Instead of a light table and gridding tape, I'm using a vector drawing program. This part can take weeks.
Once the traces and the features are recorded, the work is separated into colour layers, and printed as solid black onto clear film.
A mesh is coated with a photo-sensitive emulsion, and a powerful UV light is shone through the film, onto the mesh.
The parts that receive the light become cured, while the parts that are blocked by the solid black artwork stay soft, and then they get washed out, blasted away with a power washer, leaving a kind of stencil embedded in the mesh.
A batch of coloured ink is mixed up, and pressed through the stencil using a squeegee, onto a sheet of thick printmaking paper. There's one layer of printing per colour, so most have four: A background, a colour to show the circuits on the bottom of the board, a colour for the circuits on the top, and a colour for the exposed copper pads, gold fingers and through-holes that join the two layers, and where components are mounted.