Homebrew PCBs

Hi Guys,

This is the first time i have run across something like this.  I was 
doing some experimenting with the ink over the weekend for etching.  
Anyway, I dipped a board in Ferric Chloride for about 10 seconds or 
so to give it a dull surface.  I rinsed it off, not super good, but 
rinsed it and left it to dry in my soldering jig.

It turned all black.  So, I just took some scotch brite and started 
to polish it and began coughing right away.  It appears as though 
the copper oxide (whatever the black stuff is) can be a repiratory 
irritant of some sort.

Generally stuff doesn't bother me - I smoked for for 35 years or so 
and work around dust all the time in the woodshop.  Very little has 
ever got me coughing that much that quickly.  So, I just thought I 
should mention this in case someone else runs into something similar.

Chris