Opps, I forgot of mentioned that the reaction needs lots of
atmospheric air !. keep the container open.
Copper doesn't react with HCl acid by its self. There is probably
a complex oxidation process happening with the wetted copper,
air, and HCl. I know that several copper compounds are made in a
similar way. I once made copper acetate with vinegar and copper,
but it took days just to get a tablespoon of the dried salt.
I actually had the container outside completely exposed (covered
with a shade cloth to stop leaves blowing in), so I suppose
that's why it seemed to work faster that what you are
experiencing. You could of very well seen the formation of blue
cupric hydroxide before your eyes. The oxygen starved environment
was preventing it from happening before you removed the lid.
grantfair2001 wrote:
> Hi Adam- I was not feeling mislead, I just did not know what to expect.
>
> The copper has only been in the acid for 18 hours. The acid still
> looks clear, as it did when I poured it into the water. The copper in
> the air looks much as it did at the time of my last post.
>
> I hadn't measured the room temperature when I wrote the above, so I
> went and did this. The etchant temperature is about 65 deg. F.
>
> As I measured the temperature, before my very eyes on several spots on
> the exposed copper wire a turquoise blue coating appeared. That was
> quite amazing! So I have every reason to believe that things will
> unfold as they have for you.
>
> The tank has been covered with its cover, which has a 9/16" hole in
> it. Does this process need lots of air exposure at first? Or was it
> just coincidence that when I took the lid off to take the temperature
> the process evidenced itself?
>
> I did put the entire 1.8 kg of copper in at the start.
>
> Thanks for your continuing advice, information, and encouragement. I
> will keep the list posted about the progress of the etchant.
>
> Grant
>
> --- In Homebrew_PCBs@yahoogroups.com, Adam Seychell
> <adam_seychell@y...> wrote:
>
>>You should put full 1.8kg of the wire in. I takes about 24 hours
>>for the acid to really start going dark and cuprous/cupric
>>chloride mix to be produced. The copper in the air should
>>eventually go bright blue Cu(OH)2 coating.
>>Has the HCl still changed from its normal pale yellow to a dark
>>brown ?. If so then its working. This reaction is an accelerating
>>one.
>>I'm sorry if I misguided you and you feel its not working as
>>expected. I've made 2 batches so far, using this technique.
>>Eventually I would like to write a web page giving much more
>>accurate information than I have done so in these posts,
>>including pictures. I'm still experimenting myself at this stage.
>>
>>Just add concentrated acid from now on, there should be enough
>>water for the moment. Don't hesitate to ask any questions.
>>
>>Adam
>
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