Ferric chloride again :(

Discussion in 'Off-Topic' started by Robin Mitchell, Feb 15, 2011.

  1. Robin Mitchell

    Thread Starter Well-Known Member

    Oct 25, 2009
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    Hi everyone,

    Just to make sure with people who have used ferric chloride, what will happen if it gets on my hands? some websites say that it does nothing and some say it burns.... so what is the truth? Is it letahl? Is it harmless to organic things?
     
  2. Markd77

    Senior Member

    Sep 7, 2009
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    Pick up some disposable rubber gloves and avoid the problem. Eye protection is a good idea too.
    I've had some on my hands for a short time, I rinsed it off straight away and it didn't seem to do anything at all, but best to avoid it.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    Other than stains, it's pretty harmless. I have reached into my sprayer tank to rescue a PCB that fell off the holder. I had the stuff up past my wrist. I rinsed it off - no burns or stains on my skin and nails. I would rate it as safer than HCl. I have been using the same batch for 8 years now, so it's economical to use.
     
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    I think the staining comes from the type of water used, can't prove it though. When I used distilled water it did not stain. The next time I mixed with tap water and it did stain. The same bottle of ferric chloride powder was used in both batches. A reaction with minerals in the tap water? Don't really know.
     
  5. BillO

    Well-Known Member

    Nov 24, 2008
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    Ferric Chloride itself is not very toxic. In solution in water, it can be quite acidic and may irritate sensitive skin. However, if you are using this to etch circuit boards, the by-products include Ferrous chloride and copper(II) chloride (CuCl2). Copper(II) chloride is toxic.

    I'd advise the use of rubber gloves and tongs.
     
  6. Georacer

    Moderator

    Nov 25, 2009
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    And by all means watch out for those stains! They don't come off at all at porous surfaces. My bathtub still has pale yellow spots after only one use of the mix.
     
  7. magnet18

    Senior Member

    Dec 22, 2010
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    You etched circuit boards in your bathtub??
    :eek:
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I think he mean spots. Etching in the bath tub sounds perfectly reasonable to me. At least, it is not likely to contaminate food. Ferric chloride will almost instantly stain or etch stainless steel or ceramic surfaces. There might be ways to remediate the ceramic stains with ammonium citrate complexes (i.e., to form ferric ammonium citrate) or oxalic acid, but that is just a guess. It may just turn it another color.

    John
     
  9. Georacer

    Moderator

    Nov 25, 2009
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    I knew that it would be stain-prone, so I had running water flow on the bathtub floor when I poured the FeCl out. But some drips flew on the bathtub walls and spots formed there.

    Where else could I have poured it?
     
  10. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Hi Georacer:

    I do "it" in the kitchen sink. But then I don't have a wife here to complain. I think the bath tub is a good place. It is certainly better than the toilet. Try the remedies for iron stains I suggested.

    John
     
  11. magnet18

    Senior Member

    Dec 22, 2010
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    Ok, pouring makes more sense. I thought you'd just soaked the boards in the tub. I'm pretty sure you'd never get that amount of stains out. :)
     
  12. Wendy

    Moderator

    Mar 24, 2008
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    You guys are crazy, copper pipes and FeCl?

    I use tupperware, toss in some wire, and seal it with tape, then throw it away.

    The acid I pick weed I don't like.
     
  13. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Why the wire? Does it help to neutralize the acid?
     
  14. Georacer

    Moderator

    Nov 25, 2009
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    I don't think that it will harm the piping in such a diluted state, Bill. I make sure to pour it over a fully opened faucet. Not that I etch at home any more. When I design something, the scale usually demands a PCB service.

    Thanks for the advice, John!
     
  15. Wendy

    Moderator

    Mar 24, 2008
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    The stuff is designed to eat copper, dilution helps but it will still react. So do drain cleaners, but at least you are getting a service with it. I doubt the water treatment plants are very equipped to handle it either. Replacing pipes is very, very expensive.

    Technically FeCl is a salt, just like NaCl (table salt). It is very reactive though, so I give it something to chew on to reduce the reactivity over the long term.

    Hydrochloric acid is just chlorine and hydrogen, and H2O2 is oxygen and hydrogen. I have no problem getting rid of small quantities in my yard. I stay away from any metal though.
     
  16. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    First, very few of us have copper drain pipes. Second, contact time and concentration make a huge difference. And finally, water treatment plants are the major industrial user of ferric chloride in most cities. They are more than equipped to handle it. That add it to the sewage (http://en.wikipedia.org/wiki/Ferric_chloride).

    HCl plus NaCl is pretty reactive too and will etch many metals, including stainless steel. It's the high chloride concentration that is the culprit. (Agua regia is the same principle and will dissolve gold.) Giving it "something to chew on" only increases the amount of copper pollution you are adding. If you are going to dump it, just dilute and dump it.

    John
     
  17. Wendy

    Moderator

    Mar 24, 2008
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    PVC may be the main material in that neck of the woods, but I've only seen copper plumbing around here. PVC may even be the main material around here too, I'm not a contractor, and I live in an old house with thin pipes (thin from use). From what I've seen the service pipes (water and sewage) are also metal.

    I hadn't heard about FeCl used in water treatment plants. I think it was used for ink during midevil ages.

    I've mentioned it before, but some dissolved FeCl did a number on my tools in a supposidly sealed plastic container from the fumes. I'll be keeping it away from my pipes in any form.
     
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