Homebrew PCBs

I'm trying to wrap my head around how this works, to better mix it.  I
actually like working with this method - the resulting etchant is way less
unpleasant than ferric or the HCl/peroxide stuff.  It is way slower,
although I've found adding peroxide/salt seems to speed things up a bit.

 

The only negative I've found is that peroxide typically is only available in
small 300-500ml bottles, which depending on which store you raid cost
anywhere from $1.99 to $3.99 CDN each.  And you kinda get weird 'is this guy
a terrorist?' looks when you check out six or eight of em at a time.  I've
looked around for 'bulk' peroxide but have only found industrial stuff that
is at 32% (vs 3%).. wondering how that would change things in the reaction?

 

I'm also wondering why it seems like I can keep the reaction going
indefinitely if I constantly intervene to stir, add a bit of salt, add
peroxide, etc.. but once I let it go it cannot be restarted again.  Also
curious why sometimes I get a blue coloured etchant at the end, whereas
other times I get this foamy, nasty green.

 

I'd love to figure this out more and refine it.  The real obstacle is the
cost and small quantities available of peroxide.  I'd love to find a way to
buy that that doesn't leave me feeling like a weirdo.  :)

 

Brad