[sdiy] making PCB's with PNP blue

[Colin f]

> I also use ammonium persulphate as an etchant. Used ferric 
> chloride before, never again. Messy, messy, messy. And you 
> often can't see what's going on in the solution.

Ditto that. I put a lamp behind my bubble tank, shining on the back of the
board being etched.
You can see clearly when the etching is done, and any unevenness in the
etching from poor distribution of the bubbles.

Cheers,
Colin f