Homebrew PCBs

Charlie,

Well, I may have overstated the nastiness of the fumes. It's really no
worse in use than, say, photo stop bath or fixer--both of which have a
fairly-strong acetic-acid (vinegar) smell. There's no evil-scientist smoke
or anything. For me, it's a kind of DIY thing. I make my own salad
dressing, too . . . not with the hydrochloric, mind you!

73,

Todd
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K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
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QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


On Wed, Mar 13, 2013 at 9:09 AM, Missouri Guy <n0tt1@...> wrote:

> OK, thanks Todd.  Nasty fumes from the stuff!!  I think I'll just
> stick with the Ferric Chloride....seems to be the most "user friendly"
> for occasional use.
>
> Good idea on the vent system you have there!
>
> 73,
> Charlie
>
> On Tue, 12 Mar 2013 22:25:31 -0700 "Todd F. Carney / K7TFC"
> <k7tfc@...> writes:
>
> On Tue, Mar 12, 2013 at 6:52 PM, Missouri Guy <n0tt1@...> wrote:
>
> > **
> >
> > . . . Lemme ask this...I'm assuming that the etching should NOT be done
> in
> > full sunlight because of the H2O2. Is that correct?
> > Or does it make any difference because it is mixed with the
> hydrochloric
> > acid? . . .
> >
>
> Charlie,
>
> I don't know anything about the photoreactivity of the mixture. The high
> UV
> from the sun probably does something. The stuff should definitely be used
> outside as it has very pungent fumes, mostly from the acid I think. Care
> must be taken in just opening the acid jug, it's that strong. Naturally,
> proper protection for the eyes and bare skin is in order. I use shop
> goggles and exam gloves and I wear old cloths. In this winter cold, I
> used
> a rigged-up vent booth in my laundry room for both small-object spray
> painting and etching. A strong fan in the back of a big cardboard box
> just
> blows the fumes out the window.
>
> Regarding disposal, there has been a thread running lately in this group
> you should look up. Since I use my 2:1 etchant "one-shot" in 2oz
> quantities, I once just poured it down the drain afterwards. Deciding
> that
> was not responsible, I then began to dump the "shots" into a bucket
> filled
> with wood shavings. I assumed the shavings would "sequester" (oh, that
> word!!) the copper-ladden chemical in a form that, once dry, could just
> be
> carefully bagged and sent to the landfill.
>
> This morning, though, I read a post from . . . damn!, can't remember his
> name . . . who observed all I was doing was to create more toxic waste.
> He
> suggested the spent etchant be treated with sodium carbonate. This would
> have two benefits: it would neutralize the acid, and it would precipitate
> an insoluble copper compound that could then be filtered out and dried
> before ordinary disposal. He further suggested the precipitate could be
> made even safer by baking out carbon in the form of CO2, leaving behind .
> .
> . damn! I can't remember the compound that would remain . . . but he said
> it could be very safely disposed of in the landfill. I'm going to pursue
> this idea. Check out the thread.
>
> 73,
>
> Todd
> ----------------------------------------------------------
> K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
> ----------------------------------------------------------
> QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
>
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>
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