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Goldstripperbad


#1

Actually it’s a spezielles behandlugsbad- meaning “a special
treatment bath for goldstripping”. That’s it folks. Now all of
you know what that is right? Well I don’t. And that is why I’m
asking for your help.

I’m reading this book from the Platinumschmidt series from
Germany and in it there is a segment on the casting of fine gold
into palladium.

In the finishing sequence there is the aforementioned schtuff
that is supposed to make the grain boundaries of the fine gold
and the 750 palladium clearly visible. There is a picture of the
ring suspended in the beaker using rubberbands(hence -not
electrostripped). I don’t know if this is an oversight on behalf
of the editors (not disclosing the chemicals) or if this is
intentionally left out to cause people like me to go into a minor
fit because there is a conspiracy by some to withold important
details from the many.

            Dankeshein,  Peter Slone

#2

Hi Peter,

Sorry, the word is spelled Danke-schoen, and it is all one word,
Dankeschoen!

Chuss,

Skip


#3

I use aqua regia to get the texture that you are talking about.
I leave it in about 8 hours. If you want to get better grain
growth you can put it in the kiln at 900 for several more hours.
this help grow the crystals. There is a special solution you can
get from germany but as you had pointed out not all is given away
. I fuse the gold into the Platinum by heating the ring up to
orange color and touch a gold wire to the ring and the gold will
flow into the depression. build the area up above the surface of
the platinum then tap down with a planishing hammer to compact
the gold making it dence and ensuring there is no pitting. you
can do this with 22k, 18k and 14k

Edward J. Friedman
Revere Academy


#4

Edward:

I noticed your post and have always wanted to know if there was
a safe method to accomplish the crystaline finish I’ve seen on
platinum pieces. After melting the gold (18k or 14k?) into the
depression, do you simply soak the piece in aqua regina or is is
done electricaly? Could you please describe the complete
process?

Many thanks;

Steve


#5

Edward, I am also curious about melting gold into the
depressions of platinum and wonder if you have had any luck in
doing this with other metals. Also, can anyone elaborate on
Bi-metal casting. I read the article in AJM regarding this but no
mention of using silver as the metal to be cast- other than in
mentioning that high copper alloys tend to oxidize too much to
support a good bond between metals. I did have some positive
results by embedding 750 Au, 12.5 Cu, 12.5 Ag in wax and casting
.925 with a smidgen of zinc in an invested flask with 2% boric
acid. I have no clue as to how the boric acid is going to help
the bonding of the two metals (does it create a reducing
atmosphere in the falsk and if so- isn’t that counter productive
to a good burnout of the wax?) -I just read that it can be good.

                                        Thankyou, Peter Slone

#6

Steve, on the use of the acid I will normally just leave
the ring in the acid for about 8 hours and not place the
ring in the oven. the grain size is smaller but there are
less steps. If you want larger grain size put in th oven.

Edward J. Friedman
The Revere Academy of Jewelry Arts. San Francisco


#7

I noticed your post and have always wanted to know if there was
a safe method to accomplish the crystaline finish I’ve seen on
platinum pieces. After melting the gold (18k or 14k?) into the
depression, do you simply soak the piece in aqua regina or is is
done electricaly? Could you please describe the complete
process?

Steve,

I fuse the gold into the Platinum by heating the ring up to
orange color and touch a gold wire to the ring and the gold will
flow into the depression. build the area up above the surface of
the platinum then tap down with a planishing hammer to compact
the gold making it dence and ensuring there is no pitting. You
can do this with 22k,18k and 14k. File the gold and sand up to
4/0 polishing paper to leave a very smooth and even surface.
You can do the process with electricty or acid

Acid: I use aqua regia to get the texture. I leave it in about
8 hours. If place ring in the acid for 4 hours then remove and
put in an oven a 900 degrees F for 2 hours to grow the grain and
then place int the acid for another 4 hours or until the desired
surface is achieved.

Electiricity: Using a rectifier reverse positive for the ring
and negative for the stainless steel beaker. Use about 12 volts
and dip the ring in the heated solution of Cyanide 120 degrees
F. Do not leave the ring in too long. Dip for 15 seconds and
check until desired finish is achieve.

“CAUTION” must be take with the use of Acids or Cyanides.

Use in well ventilated area.
Use eye protection
Safety gloves and apron

The use of your rectifier tends to remove metal very fast and at
the edge of the two metal boundries. A depression will occur at
this edge if the metal is over stripped.

Edward J. Friedman
Revere Academy of Jewelry Arts, San Francisco


#8

Edward, I am also curious about melting gold into the
depressions of platinum and wonder if you have had any luck in
doing this with other metals.

Peter,

You can fuse just about any metal to platinum due to its high
melting point. You can use any color of gold. I started with
silver and then tried gold. It is easier to remove silver with
nitric acid from the platinum to reclaim the platinum.

Also, can anyone elaborate on
Bi-metal casting. I read the article in AJM regarding this but no
mention of using silver as the metal to be cast- other than
in an invested flask with 2% boric

You can Bi-metal cast with silver, copper or any other metal use
for jewelry but the draw backs are oxides that form between the
two metals. The use of boric acid added to the investment to
protect the metal from forming oxides. Just as we use a
boric-acid -alcohol solution to protect the item from oxidizing.
There is a special investment used for stone-in-casting to
protect the stones during casting, this investment contains
boric acid.

To ensure a good bond you should drill into the metal item or
into the wax creating metal plugs that will fill when cast. This
will make the mechanical bond between the two metals. You can
also take a wire ball the end up and solder it to the ring to
create a stronger bond. Soldering the two items after casting is
also expectable to ensure the bond. I tend to solder after
casting just to make sure of the bond, it also makes the seam
between the two metals look more fluid.

I have no clue as to how the boric acid is going to help

the bonding of the two metals (does it create a reducing
atmosphere in the flask and if so- isn’t that counter productive
to a good burnout of the wax?) -I just read that it can be good.

The boric acid does not seem to be counter productive to the
casting process it is used to reduce oxides that will form on the
metal during the burnout process to allow the two metals to
adhere to each other. If you are casting gold, silver you want a
reducing atmosphere during casting.

Edward J. Friedman
The Revere Academy of Jewelry Arts, San Francisco


#9
8 hours?  You must be using Very dilute acid!.  Mixed just
straight HCL plus 

I just did two test piece and here are the following findings.

The Acid I use is a very saturated solution of aqua regia. I do
acid refining and I have not removed the gold out of the solution
so it does not have the strength fresh acid has. I have been
using a 4 to 1 ratio by volume. By weight it would be a 3 to 1
ratio. Hydrochloric at 80 percent and Nitric at 70 percent.
Before sending this to Post I used the mixture I have and it took
about five hours to etch the surface and I mixed a fresh batch
that took about 45 minutes to achieve a surface texture but the
crystal size is very small. So the need to grow the crystal
either by annealing , oven tempering or possibly starting by
reverse stripping to start a larger grain growth. It is
important to use cold Aqua Regia to ensure the acid does not
affect the platinum.

Edward J. Friedman
The Revere Academy of Jewelry Arts, SF CA