[sdiy] preventing corrosion on bare traces

[media at mail1.nai.net]

I've noticed that "vectorbords" and newly etched PCB's tarnish very
quickly.  I can't help but think that this will eventally corrode the
traces to the point where it effects the circuit.  What is the best way to
protect the copper??  Is there some sort of spray??  I wouldn't want
anything that would prevent future modifications and repairs.

THANX!!