Silicon on copper - colours separating

A few days ago I experimented with pouring different colours of silicon, some opaque and some transparent onto pieces of copper, and I left them overnight to dry.

When I returned this morning, the navy blue ink had changed from a block of colour and separated leaving little channels. Strangely, some areas of the silicon had not dried or set onto the copper. There could be a number of reasons for this, and so further experimentation is required...