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Keum Boo on Pre-fabricated piece


#1

I need some technical advice. I have been struggling with my keum
boo applications bubbling.

Keum boo on a fabricated piece.

  1. I soldered a small piece (a circle) of sheet fine silver over a
    sterling sheet backing or base to create my design.

  2. I then tried to bond the gold on just the fine silver surface(s)
    circle.

  3. I have found that the keum boo bubbles, and I cannot seem to get
    it to bond evenly to the fine silver surfaces no matter how much I
    burnish it or poke the bubbles with a pin and reheat it to burnish
    the bubbles out of the surface.

What I have been told is that the keum boo on the fine silver is
bubbling because the solder has corrupted the fine silver. This is
hard to understand because only the fine silver back of the circle
was sweat soldered to the base and the fine silver surface does not
have any solder on it.

  1. Do I bond the keum boo foil FIRST to the fine silver and THEN try
    to solder it to the base pieces?

  2. If so, what problems do I face when I do solder the gold bonded
    fine silver to the base? (Bubbling? Melting? Getting absorbed by the
    silver because of the heat?)

Has anyone had similar problems? If so what works for you. I see
Keum boo jewelry that has layers of silver and gold on them. They
must have been soldered at some point.


#2

Keumboo

Id say if youre silver is super clean, then your gold leaf has been
poluted (a fingerprint is enough) clean with a volatile solvent that
doesent leave residues, try anny solvent on a piece of glas and let
it evaporate if ther is nothing left after the solvent is gone youre
good to go.


#3

Hi Noreen,

I doubt it’s the solder. I’ve done it on all sorts of soldered
pieces with no trouble. Didn’t even bother with a fine silver piece,
just depletion gilded the sterling.

It’s more likely to be either

A-overheating. What are you heating it with?

B-foil is too thin. How thick is it? Where’d you get it? Or did you
make your own?

C-the burnisher is galling the gold. Iron burnishers gall gold foil.
I use haematite burnishers. No galling.

I also use fairly thick foil. (.0008", more or less, which is about
the thickness of the double thick sheet that Allcraft sells. Means
you don’t need to worry about it fading in, or turning green through
diffusion.)

Regards,
Brian

Tapped out on my iFernal device. Please excuse any brevity or typos


#4
1) Do I bond the keum boo foil FIRST to the fine silver and THEN
try to solder it to the base pieces? 

Keum boo is last, always last.

I have not experience bubbling as you describe.

What are you use for your heat source? Are you using the right kind
of nice, thick foil? Agate burnishers are awesome.

I do keum boo on an electric stove top thingy, you know, a free
standing single burner, with a 6" x 6" brass sheet on top.

Others advocate using the Beehive Kiln with a brass insert. I have
not tried that.

Celie Fago’s book on the subject is terrific.

Elaine


#5

I don’t know what is causing your difficulty, but that isn’t it. I
keum boo on sterling all the time, and often it has been soldered
previously.

Sometimes I even forget to “bring up the fine silver” and it still
works.

I suggest you try your procedure on a plain unsoldered fine silver
piece as a test. This will at least point to where the problem is or
is not. Any chance your gold is dirty? Did you touch it with your
fingers? That’s a big no-no, and I can imagine that causing such a
problem.

Not knowing your exact procedure, here are a few bullet points:

  • use foil, not leaf-- gold leaf is too thin
  • make sure the piece is very clean
  • heat the workpiece until a toothpick touched to it chars on
    contact
  • hold the foil in place with one burnisher while rubbing with
    another, until you are sure it is stuck

If I am going to keum boo on a piece that isn’t flat, I heat it with
a torch (gently). I usually position the gold while the piece is
cool, then heat it, so it doesn’t “suck down” in the wrong position
before I can shift it, sometimes burning myself.

That’s about it!

Good luck
Noel


#6

Noreen -

Here is my procedure:

I roll my own K. B. foil to about the thickness of heavy aluminum
foil. I do sometimes bond it to fine silver. When I do, I cut out the
fine silver shape and clean it thoroughly several times until I get a
cascade of water with no breaking (like for enameling). I use a hot
plate at 650 degrees F to bond the silver and gold. I tack the gold
to the silver in several places with a pyrex glass rod then burnish
heavily with a polished agate stone that is shaped like a section of
orange. The agate stone lets me lean really heavy on the burnishing.

After that, I use the piece to construct the jewelry - that is, I
solder after applying the gold.

A couple of thoughts:

  1. did you clean the fine silver thoroughly? It seems unlikely that
    solder leakage is the problem because you would see/file it off.

  2. how thick is your K. B. foil? The thin stuff is more prone to
    "disappearing" into the silver.

  3. Is your foil flat? Wrinkles in the foil can cause problems. Even
    with the thick foil I use, I do sometimes get bubbles but they
    burnish out when the piece is still hot from soldering.

  4. Is your bonding temperature hot enough? You don’t say how you
    bond the metals, but, for me, nothing happens until my hotplate
    reaches 650.

I hope this helps.

Debby
HoffmasterMetalcraft.com


#7

Not being able to watch what you are doing, I’d hazard to guess your
problems lie in one of three areas:

  1. You are not getting the metal clean enough before applying the
    gold foil.

  2. Your foil is too thick.

  3. You are not getting the silver hot enough for the diffusion bond.

If you are soldering a piece of .999 to sterling and trying to apply
KeumBoo to the .999 it is not the metal. certainly not the solder you
sweat soldered the .999 disc to the sterling with.

Here is what I do: I clean the metal thoroughly by sanding with
1200, then 4000 paper. I like a matt finish on Keum Boo pieces, then
I clean itwith acetone or alcohol. After cleaning, never touch the
surface that is going to accept the gold. Then, I cut out the gold
shapes between paper with an xacto knife. I heat the silver piece on
a hot plate on a pieceof 18ga copper. I’ve heard that some folks use
an old allclad pan on top of their stove - that seems to make sense.
I have tried a lot of waysof ensuring the metal is hot enough
including a fluke digital K probe and those point and shoot temp
probes… honestly, the toothpick method seems to work better than
just about anything. You heat the plate up, then when a wooden
toothick will char you are about right. I think that is about 600 or
700 F. I then apply the gold foil with tweezers and burnish with an
agate or sometimes a small steel burnisher. That’s it. I wear gloves
and use commercial Keum Boo foil from Rio. I’ve never tried Keum Boo
on depletion guilded metal because I hate it :slight_smile: I know there is fire
scale still under there so I hate it. only use it for reticulation.
You are not using something like Klyr Fire to adhere the foil are
you? That would probably mess things up.

I’d be curious to hear if others solder after attaching the Keum
Boo. I’ve had mixed results. My experience is the gold does tend to
diffuse into into the silver and you have trouble getting good
contrast if you are using LOS to blacken the silver parts.


#8

Thank you all for your valuable responses. I do appreciate them.

Questions - 3 more.

Running the problem to ground to find the culprit. Maybe my cleaning
solution is not good enough.

  1. What are you using to clean your surfaces?
  • I am using a brass brush then denatured alcohol

  • BUT that may not be getting the piece clean enough for the bonding
    to take place. I have not been depleting the silver because it IS
    fine silver and should bond without depletion - right?

  • What is a volatile solution for cleaning? Sounds exciting if not
    dangerous! :wink:

  1. Temperature control may also be my problem:
  • I use a (flat plate) hot plate but do not have a temperature
    thermometer (Just ordered one)
  1. How hard do you press when burnishing?
  • I use alternating agate burnishers but I don’t use heavy pressure
    as I worry about tearing the gold foil.

  • I test heat for charred chop stick or dancing droplets.

  • I use ONLY gold foil from All Craft (color is beautiful but has
    the bubbles)

  • burnish with agate burnishers do not use steel as it was tearing
    the gold.

  • gold is untouched (tweezed only in place)

I have Celie Fago’s book and she has been kind enough to communicate
with me, but she felt it was the soldered silver that was interfering
with the bonding process. Yet I see images of it being done with
other pieces everywhere

Thank you all again for your responses. I am at least isolating the
problem.


#9

Thank you for your reply. Do you have a suggestion as to a “volatile
solvent” as I have been using denatured alcohol. I have never
touched the gold with my fingers (I only use tweezers), but I am
wondering if I am getting the silver clean enough. I have used a
brass brush and then soaked the piece in denatured alcohol. I am
waiting for a thermometer to test the heat of the hotplate as I sense
that might be part of the problem. I have no idea of what sort of
volatile solvent I might try.

Noreen Mulliken


#10

acetone, bezene, xylene are all volatile solvents, acetone can be
purchased cheaply at Walmart. All are potential carcinogens, so be
careful with handling and breathing while using any of these. All are
also flammable/explosive.

john


#11
1. What are you using to clean your surfaces? I am using a brass
brush then denatured alcohol BUT that may not be getting the piece
clean enough for the bonding to take place. I have not been
depleting the silver because it IS >fine silver and should bond
without depletion - right? What is a volatile solution for
cleaning? Sounds exciting if not dangerous! ;) 

The denatured alcohol should be doing the trick. You might try a
light sanding with a very fine grit to make sure you don’t have some
tarnish there. which might interfere with the bonding. Then use the
denatured alcohol after the sanding.

2. Temperature control may also be my problem: I use a (flat plate)
hot plate but do not have a temperature thermometer (Just ordered
one) 

I’ve had issues with cheaper hot plates not getting hot enough, but
if you are doing the “chopstick” test it sounds like you are getting
to temperature. One thought. how big is the piece. Just because the
surface of the hot plate is at temp does not mean the.999 disk on
the piece is attemp. Silver is a fantastic conductor of heat, so
that is probably not an issue unless you only have a small part of
the piece in contact with the hot plate. You might try doing the
chopstick test on the piece close to the disc just to make sure.

3. How hard do you press when burnishing? 

Just the lightest touch. If everything is right you don’t need much
pressure on the burnisher.

If you can send me your mailing address offline I’ll shoot you a
piece of Rio’s gold foil for you to try. just to eliminate the
possibility the foil is contaminated.


#12

I clean my metal with Dawn dishwashing liquid and a green scrubby
pad. Again, I keep at it until I see no water breaks (like for
enameling). I air dry. I do not use any alcohols (methyl, ethyl or
isopropyl) or acetone. Also my tap water is pretty good - no sulfur
smell, etc.

As for leaning into the foil, yes, I use a lot of pressure. However,
please remember, that my foil is thicker than the commercial types.

Debby


#13

As John points out acetone, benzene and xylene are carcinogens.
Please, please, do not use them. Benzene has been banned in the US,
as it causes blood cancers, and is considered one of the major causes
of myelodysplasia. (pre-leukemia).

Alma


#14

My father worked for Union Carbide as a Chemist for many years in a
plant where their work involved benzene. He died of myelodysplastic
anemia. Bad chemical.