[sdiy] Messy workshop and Into the future (was Old Age and Synth-DIYers)

[ASSI]

On Tuesday 08 June 2004 15:43, Ian Fritz wrote:
> I really don't know. Ferric chloride is an acid, so you can
> neuteralize it with baking soda, as I remember.

No, but it is an oxidant. The problem with dumping the used etchant are 
actually the copper ions. But you can condition used FeCl3 by running a 
4:1 water diluted solution with the pH adjusted well above 3 through 
steel wool (don't use concentrated solutions as it would start to 
boil). After letting the stuff sit for a few hours a probe of the 
solution is tested with a concentrated solution of NH3 in water 
(salmiak) for residual copper. If you get blue hues, then you need to 
add some fresh steel wool. If there is no more copper in the soultion, 
it should sit in open air for a few days or better bubble air through 
it to oxidize the Fe2+ ions to Fe3+. The resulting solution can then be 
further diluted dumped into the wastewater. The copper debris can be 
filtered, dried and given into the waste in a closed bag.

Ammonium persulfate should not be used at all for etching if you can't 
dispose of it properly as it is extremely toxic to fishes (most 
commercial etchants have mercury additives on top of that). It can be 
somewhat recycled because the CuSO4 (the blue stuff) falls out if the 
solution is cooled (but you can't dump that either). Sodium persulfate 
is not toxic for fishes in low concentration, but you still have to get 
rid of the copper ions first.


Achim.
-- 
+<[Q+ Matrix-12 WAVE#46 microQkb/Omega Andromeda XTk/30 sonic heaven]>+

SD adaptation for Waldorf rackAttack V1.04R1:
http://homepages.compuserve.de/Stromeko#WaldorfSDada