I used my Intel QX3 USB microscope for this project - it's not a particularly great bit of kit - poor quality optics, low resolution noisy image sensor, atrocious software interface - but it works almost well enough for what I'm trying to do here.

The paints were just little pots of coloured decorator's emulsion (plus one of gold enamel) left over from some project or other.

The red paint was too thick and blobby to work with, so I mixed a little with some water and put a drop on a slide

The drying process wasn't really very interesting, but a noticeable change did take place.

The blue paint needed less dilution and was placed on a piece of cheap paper torn from an exercise book.

It did become a little more interesting as it dried, acquiring a sort of eggshell finish.

The green paint also needed dilution - and this time, I put some on a glass slide and lit it from below.

The drying process was quite interesting - a bit like watching a pond freeze over.

The gold paint was perhaps most interesting of all. It's an enamel paint based on an organic solvent (the others are water-based)

The particles of gold pigment were individually visible at 200x magnification, but the most intersting bit was the writhing, wavy motion of the surface as the solvent evaporated and the matrix material cured.