On 3/08/2013 2:35 p.m., Harvey White wrote:
>
> On Sat, 03 Aug 2013 13:37:58 +1200, you wrote:
>
> >On 3/08/2013 9:16 a.m., Philip Pemberton wrote:
> >>
> >> On 01/08/13 02:33, Harvey White wrote:
> >> > Why bother to go that way when the copper from the boards you would
> >> > etch would do the same, and get the boards etched? With a lot of
> >> > oxygen available, you'll find that these boards will etch rapidly in
> >> > the fresh mixture. As the O2 from the peroxide dies off, the bubbled
> >> > air will substitute for that and you're building your CuCL2 etchant.
> >>
> >> I mixed the stuff up yesterday, but I think the etchant might be a bit
> >> short on oxygen - after an hour or so it turned a dark brown and pretty
> >> much stopped reacting with anything.
> >>
> >> I've left an aquarium air bubbler running overnight with the copper
> >> removed. I'll see what that does but it doesn't look promising and I'm
> >> out of H2O2... :-/
> >>
> >
> >Try some sodium percarbonate, 1 teaspoon/50ml of water, readily
> >available as a cleaning agent. Add very slowly as it releases CO2 and O2.
>
> Not sure that this will work, but potassium persulfate is an etchant
> in and of itself. In the states, it's used as a shock treatment for
> swimming pools (the extra oxygen kills off stuff you don't want).
>
> It's about the equivalent of 3 GPB per kilo, and as such (you need
> almost that much for a single run), is rather expensive when compared
> to muriatic acid/hydrogen peroxide mix. The rather expensive (when
> new) etchant tank I have can't handle the HCL.
>
> So does sodium percarbonate work as an etchant?
>
Sodium Percarbonate (aka solid hydrogen peroxide) is a mixture of sodium
carbonate and hydrogen peroxide Na2CO3.5H2O2. When dissolved in water it
forms an aqueous solution of Sodium Carbonate and Hydrogen Peroxide. Mix
that with Hydrochloric acid and you get an aqueous solution of Salt,
hydrogen peroxide and gaseous carbon dioxide. 1Kg of percarbonate (costs
$8 / Kg in New Zealand, they probably give it away in USA) is equivalent
to 1 Litre of 35% hydrogen peroxide.
It's used in washing as a bleach
http://www.ebay.com/itm/Sodium-Percarbonate-Oxygen-Bleach-Oxyclean-Tide-1-2-lb-/190477839862?pt=LH_DefaultDomain_0&hash=item2c595d2df6 >
> Ammonium persulfate and potassium persulfate (with trace ingredients)
> are used as etchants. The trace ingredients come when you buy the
> stuff to treat pools (and they don't tell you what is.....).
>
> The persulfate etchants do not attack tin/lead, if I remember it
> correctly.
>
> Harvey
>
> >
> >> Thanks,
> >> --
> >> Phil.
> >> ygroups@... <mailto:ygroups%40philpem.me.uk>
> <mailto:ygroups%40philpem.me.uk>
> >> http://www.philpem.me.uk/
> >>
> >>
> >
> >
> >
> >[Non-text portions of this message have been removed]
>
>
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