A hydrometer is floating already....
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> Also add some hydrometers to your shopping list to cover the
> range 1.00 to 1.30 I find hydrometers with 0.10 range are plenty
> good. Standard laboratory hydrometers have a range of 0.05.
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> Looking at the commercial CuCl etchant (
> http://www.oxfordvue.com/TechInfo/how_does_it_work.html ), they
> run at s.g 1.35 to 1.4 and have about 220 g/liter of copper.
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> I think this is too high, I found 1.25 to 1.30 better for room
> temp etching. CuCl2 etching without chemical oxidizers (H2O2,
> Cl2, NaClO3 etc) should etch 35um copper foil in 20 minutes at
> 20°C with bubble agitation. Keep HCl plentiful.
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