Homebrew PCBs

Thanks DJ
Last week I had a 55 oz jar of transparent emerald green etch. Using 
this etch was SLLLOW. I added scrap copper and started bubbling. It took 
about 10 hours to turn OPAQUE. I continued to bubble for another 24 
hours. Removed the copper and continued bubbling. After 2 days, it was 
still OPAQUE. I added 2 oz HCl ... no change ... 1 oz of 27% H2O2 ... it 
turned emerald green. With the additional HCL, I added more copper and 
started bubbling. It took 8 hours for it to turn OPAQUE. I continued 
bubbling for another 4 hours. I removed the copper and continued 
bubbling and after 6 hours it turned transparent emerald green. I don't 
have an hydrometer. The color is a transparent BRIGHT emerald green no 
trouble seeing through the 5 inch diameter jar of etch ... no hint of 
OLIVE green. Should I add more copper? ... When Adam says you can't see 
through but a few mm, Is that the ready to etch transparent state or the 
spent OPAQUE state?
Jim KI6MZ

On 5/9/2011 11:46 AM, DJ Delorie wrote:
> The only way to know how "strong" your CuCl etchant is, is to use a
> hydrometer.  The copper makes the solution more dense, by measuring
> the density you can determine the copper concentration.
>
> See http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/
> for all the details.
>
> Note: my solution looks like the photo at the top of Adam's page.
>
> "Spent" etchant is opaque BROWN.  This may look like dark green at first
> because it's mixed, but see Figure 5 on Adam's page.
>
>
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