Re: Recovering gold from ceramics gold paint

Bob wrote:
>
> "Uncle Al" <UncleAl0@xxxxxxxxxxxxx> wrote in message
> news:42EA75F5.F149CA91@xxxxxxxxxxxxxxxx
> > Bob wrote:
> >>
> >> I've got some Heraeus "Liquid Bright Gold" paints, types GG 1517- 10% and
> >> GG1300-10%. These are used to decorate ceramics and are thick dark brown
> >> liquids formulated with solvents like Dipentene and Dichloromethane with
> >> some gold compound. When fired they should give a bright gold finish.
> >> Both
> >> are well past their sell by date and I want to recover the precious metal
> >> content (about 5 grams, I think) rather han just throw them away. What's
> >> the
> >> best way to do this? The paints are quite viscous, so I imagine I'd need
> >> to
> >> thin them with some kind of solvent (white spirit?) and then add
> >> something
> >> to precipitate the gold?
> >
> > What makes you think the gold is in there metallic? If it is
> > metallic, dilute with something miscible of low density like toluene,
> > acetone, or methylene chloride, or commercial paint thinner. The gold
> > will sink.
> >
> > More likely you've got reactives like moisture-curing
> > tetaethylsiloxane to set the gold in place before firing. The gold
> > itself is probably in there as a homogeneously soluble salt or complex
> > that reduces to metal in the kiln at temp and won't settle out in the
> > paint. If the gold is not metallic you must reduce it to metal to
> > recover.
> >
> > If you do have cross-linking reactives, diluting with moist solvent
> > will rapidly become a terrific mess. Uncle Al once diluted RTV resin
> > to use as a brushable mold release. Work fast or it gels as you watch
> > it.
> >
> > Is there a patent number on the can?
> >
> > http://www.uspto.gov/
> >
> > If it is only organics I'd evaporate off the volatiles then fire to
> > recover the metal. If you have reactive silicates and combined gold,
> > maybe activated zinc dust (reduce the gold) in dry methanol (to thwart
> > silicate dehydrative condensation). If it is any more "interesting"
> > than that the game goes into extra innings. Call a refiner like Aesar
> > and ask what the stuff is worth unaltered in the can.
> >
> > --
> > Uncle Al
> > http://www.mazepath.com/uncleal/
> > (Toxic URL! Unsafe for children and most mammals)
> > http://www.mazepath.com/uncleal/qz.pdf
>
> There's an old recipe for coating glass with Platinum, from before the days
> of vacuum evaporation, which consists of a solution of platinum chloride in
> oil of rosemary/ oil of lavender. You paint it on and then heat turns it to
> a jet black mirrored surface and more heat turns that metalic. Judging by
> the aromatic smell of these "Liquid Bright Gold" paints, and having tried a
> drop on some glass tube, I would guess they are a solution of Gold Chloride
> in similar oils. I'm guessing there won't be any siloxane type additions. I
> hope to precipitate the gold from solution, so lowering the viscosity will
> help the dust to settle. I thought of using zinc dust, but it would be nice
> if I can get the gold to precipitate pure. What would break the gold
> chloride apart and release the gold?

"guessing?" With two ounces of gold money? Look up the product's
patent. You can reduce aqueous gold salts with with oxalate and fire
off the organics. If you reduce with hydrazine or ammonia you get
"explosive gold." Uncle Al knows a self-tattooed jeweler. You still
want to know what you've got before you diddle.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.

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