Questions for people who understand chemistry.

My ferric chloride or Iron(III) chloride had a coppery type of residue after some use.I have just filterd the residu out of my ferric chloride with a coffee filter.



Questions..

1/ Is my ferric chloride still ferric chloride.. or has it changed due to the disolved some copper making it someithing else?



2/ The residue I have fillterd off with a coffee filter is that mainly copper or copper and large ammount of the ferric chloride.



3/ Thus my filterd ferric chloride is still ferric chloride or still a dead batch ferric chloride?



4/ if I add more ferric chloride to the filterd reidue will it be less effective than making afresh batch?



I would like to use the self generating etchant but in the UK I think buying the 3 or 4 chemicals to make it will be difficult..

Link to the recipe of how you make self regenerating etchant...



[members.optusnet.com.au]

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Took a trip out to Maplin and bought new ferric chloride crystals..

The diffrence is quite noticeable dead ferric chloride is greeny Yellow in colour.
The new ferric chloride is a very red colourd yellow.

Filtering old ferric chloride gets rid of the messy residue.
However it has little or no effect on the ability of old ferric chloride to etch.. a PCB..

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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

Without going into all of the chemistry junk, basically during the etching process the Iron(III) is reduced to Iron(II).
The Iron (II) drops out of solution as rusty colored mud looking mud.
The dissolved copper will settle out of solution in the form or blue, green, or possibly black solid salts.

Your coffee filter looks like it is mostly full of Iron(II) with a little bit of copper salt in it. Most likely most of the Iron(III) has been
converted down to Iron(II) and the solution is no longer useful for etching.

Adding more Iron(III) chloride to the filtered solution will help reduce the etching time, but it may just be easier to make a new batch.

As for the self regenerating etch bath, it works better than ferric chloride if you are etching a lot, but if you only a do a board every now
and then I'd stick with a ferric chloride or muriatic acid bath.