What is Jewelry bombing?


Happy new year to one and all. I am new to this forum and am enjoying
reading all the responses I have tried to geather about
jewelry bombing I know it is a reaction between caynite and hydrogen
peroxide but in what percentages and what do you do when it goes out
of control

Gary Udhwani

Bombing is done with hydrogen peroxide and cyanide (can’t off hand
remember if it is potassium or sodium cyanide eggs), it is literally
an explosive exothermic reaction and should only be done by carefully
trained people wearing protective clothing and under a fume hood.
There are probably more precautions that should be taken as well,
and local environmental restrictions may apply. I sometimes wonder
about the current health of the kid who was doing the bombing at the
factory in Pawtucket that I worked for in the early 1970’s.

Bombing should be completed in an extractor chamber with rubber
gloves, although i have never used one in 30years bombing daily.

I use 1/2 teaspoon of cyanide to 1/2 litre hot water [almost boiling]
and depending on the item/s add 2+1/2 to 3 mls of peroxide - always
step away and NEVER inhale the fumes, i use an extractor hood on full
speed - if a spill occures it must be well cleaned up.

For those well experienced in bombing that wish to perfect the
results - after the initial complete bomb[s] try cooling the hot
water/cyanide mix ‘slightly’ by adding a little cold water, then add
approx 2mls of peroxide to the item[s] while moving the container
fast in a circlular motion and then kill the reaction quickly by
adding cold water before the chemical reaction gives a full bomb.This
process may need to be completed several times and at reduced active
times as you progress.

Once perfected you can obtain results that are quite outstanding - i
have several local jewelers prefering to send me their bombing items
instead of doing it themselves, also i often use this partial bombing
system to rings and bracelets that have some plating used on them as
it does not remove it.


Happy new year to one and all. I am new to this forum and am
enjoying reading all the responses I have tried to geather
about jewelry bombing I know it is a reaction between
caynite and hydrogen peroxide but in what percentages and what do
you do when it goes out of control 

Well, first off, be sure you understand the dangers. Your spelling
of cyanide as “caynite” makes me wonder if you should be near this
stuff. If it’s just a language translation problem, then OK. If not,
be sure you’re well educated in the use of these before going near
them, for your own safety, and that of others around you.

One chemical used, hydrogen peroxide, is usually used in pretty
strong form, ie 20 to 30 percent (unlike the almost miniscule
percentages used in pharmacy “disinfectant” types.) At these
strengths, it’s a powerful oxidizer. I’ve never seen it start
something on fire, but am told that’s possible. And I HAVE seen a
spill of it leave what appears to be a pretty good burn mark on a
wood table top. Certainly, even brief contact with skin can leave a
painful burn.

The second chemical, is either sodium cyanide or potassium cyanide.
Both are lethally dangerous if mishandled. Contact with acids,
especially, releases colorless hydrogen cyanide, a lethal gas with
only a mild odor that killed it’s discoverer, and used to be the
killing agent used in gas chamber executions. Generally, when
accidentally produced, the gas can kill those around before they even
realize there’s been a problem. This is not something to play around
with casually or without proper equipment. Without contact with
acids, of course, both chemicals are widely used in electroplating
baths, and metal cleaning processes in industry, but again, this
isn’t something to use casually. Ingestion of even small amounts can
be quickly lethal (seconds or minutes). Less than half a gram of the
stuff can kill you, and much smaller amounts can do damage. And even
when used safely and sanely, cyanides pose environmental risks when
disposed of in waste waters if not properly neutralized first. If
you’re using it, you no doubt face a wide array of various government
regulations on how it can be handled, stored, and disposed of.

Then there’s also the observation that today, with modern
electrostripping solutions, or the advent of modern tumble finishing
methods, often there’s no real reason to “bomb” anything, since
similar results can often be attained by safer means.

If, after reading all my prior warnings, you’re still keen, then
here’s my experience, from years ago, back when I was still stupid
enough to do this. I worked for an employer in a very small studio,
and she’d learned this from some old jeweler she knew or something.
She felt that since it hadn’t killed her yet, nor anyone she knew, it
must be safe enough. I was dumb enough to go along, and fortunate
enough that the worst I ever had to show for it was a splitting
headache. No doubt, I was very lucky.

We use bombing mostly for things like chains, hard to clean up and
buff otherwise (this was before magnetic tumblers). It worked best
for us with 14K yellow gold. white gold would get a frosty finish,
and 18K often would get a slightly frosted look with the crystal
structure of the metal etched in, though not enough to be a good
attractive “crystal” finish. but it left 14K yellow gold bright, a
richer yellow color, and unlike plating or electropolishing, the
finish was even all the way into all recesses and interior areas.

We used a plain plastic half gallon pitcher for this, though
sometimes I’d used a covered glass coffee pot sort of container.
About a half cup or so of water was held so the nozzle of our steam
cleaner was fully immersed in it, and the foot pedal held down until
it was boiling (Like steaming the milk for your latte. much faster
than boiling it any other way, but other ways would work fine.) Had
to be boiling. In would go the jewelry, where it would be joined by
about a teaspoon of potassium cyanide powder (which seemed to produce
a faster more energetic reaction, which we felt gave a better result.
This would amount to a total mass of less than a cup of stuff in the
bottom of the pitcher. We’d swirl that around for a moment, and it
would by then have dissolved the cyanide and be lightly cleaning the
metal. Then in would go a small bit of peroxide. We didn’t measure
carefully. Just pour from the bottle. Call it a “glug”. Likely the
volume was about two tablespoons perhaps. Just a litle bit, at any
rate. The pitcher would now be lightly swirled, all the while being
sure to hold it at an angle pointing well away from oneself, towards
the back of the sink or bucket in which we did this. A high back wall
right next to the sink or bucket was and is essential. You could stop
it at any time by adding cold water to dilute, but we didn’t. First
the mix would lightly bubble for a bit, increasing in intensity,
then suddenly it would “burst”. Almost an explosion, but without much
force. You’d feel a bit of a bump on the pitcher, and the mix would
froth up from the bottom of the pitcher in a rapidly bubbling and
steaming mix. Mostly you’d need to expect it, so as not to be startled
into dropping the pitcher. The reaction would vary some (due no doubt
to our imprecise measurements of chemicals) from a fairly gentle quick
frothing up that stayed in the pitcher, to a pretty sudden burst that
could shoot pretty forcefully out of the pitcher, which was why it
always was aimed at the back wall of the (deep) sink in which we did
this, so as to catch it all without spilling or sending it all over.
The result was then rinsed in hot water. If we wanted the final deep
pure gold color, it was done. If not, we’d leave a bit of hot water in
there, and add another pinch of cyanide powder, which would quickly
remove that deep pure gold surface color, leaving the same bright
color in the actual color of the alloy.

Now, Having written all that, i can just imagine much of the
readership of Orchid cringing, either at the safety risk, or the
realization that the waste product was going down the sink drain.
Neither was good, but like I said, I was a lot younger and dumber,
and it was the way my boss did it, so it was the way I did it. For
what it’s worth, my late father, a research chemist by trade, had
heard this process described by me, and didn’t express outright
horror, only hope that I knew what I was doing… (great patience
there). And this IS, for better or (mostly) worse, how a lot of folks
used to do it. In an edition of one of Murry Bovin’s books from the
’70s, he describes pretty much this same procedure. So there’s a
certain tradition to this method, safe or not.

I like the actual results of the process. Unlike electro methods, it
doesn’t affect high spots more than low, and when it works right,
it’s a very nice uniform finish. If you don’t like the results, just
repeat it and see if that’s better. it’s very quick to do.

The downsides, well, you’re handling, as I’ve mentioned, two
potentially lethally dangerous chemicals, and maybe, if doing as I
described, doing it recklessly. Better would be to do this in a fully
enclosed lab hood, with good ventillation so you’re not breathing the
fumes. it doesn’t generate lots of specific fumes, but there IS
steam, and that will carry some of the chemicals with it, so you DO
get some exposure. Enough, as I’ve said, to give me a pretty nasty
headache a couple times. And if the “burst” goes out of bounds,
you’ve got a toxic spill to clean up. Not good. Second, from the
moment the cyanide hits the gold, it starts dissolving gold at a
fairly rapid rate, and the peroxide speeds that up. If you bomb stuff
a couple times, you’ll find the removal of metal from the surface
reaches measurable levels. So that brown yucky waste liquid contains
enough gold to be very much worth reclaiming, and you’re jewelry is
getting ligher in the process. Don’t just throw the waste away. In
addition to gold, it will contain both traces of cyanide that maybe
didn’t fully react, and the portions that reacted with the peroxide
to form cyanate, which fortunately, is less toxic than the original
cyanide. The whole waste product is still not safe, nor safe or legal
to dump down the drain.

Were I doing this again, a couple additions would need to be made to
this process. First, for safety, I’d want to do this in an enclosed
"glove box" type thing, so neither fumes nor liquid could reach the
outside or the user. Good ventillation with chemical fume filtration,
exhausted to the outside would be added. There are commercial units
available specifically for this process. They include carbon filters
and a cyanide destruct unit that first reacts the waste with acid to
destroy any cyanide, while then filtering out and trapping the
produced hydrogen cyanide gas. Needless to say, this should not be
equipment you build yourself without a good deal of chemical
engineering background, but were I doing it, I’d skip the cyanide
destruct unit, opting instead to contain the still dangerous waste
liquid for seperate processing later. And that would be the other
main addition to what I once did. Nothing goes down the drain. It all
gets saved. The resulting brown waste liquid can be neutralized and
it’s gold reclaimed. You’d want to consult with your refiners to
determine the best method of doing that for your own situation.

As a final note, please consider using this posting as l
data only, rather than instructions you should follow. The procedure I
knew and used is one I do NOT consider safe, nor the best way to do
it. Certainly, in industry, when it’s used properly, it’s different
from this. Commercially used bombing stations, when used as intended,
don’t normally have to contend with that “bursting” or explosive
effect, yet still get good results. And they do it a whole lot more
safely than the method I described. Don’t ever forget that done
wrong, this is a highly dangerous method. Just because some oldtimer
jewelers may have done this now and then does not legitimize it or
make it safer. I’m not just being a politically correct prude here.
This really IS potentially dangerous stuff, OK? Be SURE you’re
properly equipped and educated before doing any bombing. This posting
has not done the educational part sufficiently.

Peter Rowe

1 Like

Great job explaining the bombing procedure, Peter. I worked in a shop
over two decades ago that bombed sterling to remove the firestain. I
had no idea what the process was, and it demonstrated right in front
of me with NO VENTILATION!!! Needless to say, when I saw that
mushroom cloud, it was time to start my own business. Bombing did a
great job stripping, but if anyone here is contemplating it…don’t!
Find a company that has the ventilation and know-how, and let THEM
deal with the hazardous materials. I’m all for saving time and money
by doing a process myself, but this technique will kill you if
handled improperly. IT WILL KILL YOU! And keep in mind–if the fire
marshal sees this stuff in your shop, he’ll make note and probably
report his findings to DEM (Department of Environmental Management).
And once they have your name on file, they may just want to see what
else you’re using in your shop

Jeff “My Two Cents” Herman

Dear Peter,

I read your detailed bombing instructions while remembering the many
times I performed almost the exact procedure you described, with the
only exception that I did the mixing under the exhaust hood of my
burn-out oven. Back then (up to the early 80’s) out catalog included
some rings that were labeled “bombed finish”. The obvious benefit was
better evacuation of fumes, the drawback was virtually no splash
protection for the equipment or casting room.

Since that time I have removed all acids and cyanides from by
building (properly, by the way) and refuse to perform any process
that incorporates any hazzardous materials of any type. Like you, I
am amazed that I am here to tell the story.

Jon Michael Fuja

Thank you once again Peter for putting your fingers to the keyboard
and telling about the dangers and process of cyanide bombing. I use to
work with cyanide in photo lab work and it was always treated with
the highest of care.

Many years ago I had a couple of friends who had a plating shop as
part of their jewelry business and they offered plating services to
the community. One day they were found by a customer in the plating
lab both dead from cyanide poisoning. In my opinion one would be very
foolish to use cyanide in a small shop environment in today’s world.

Mark Johnson
Silver Squirrel Designs

Well said, Peter Rowe!

My experience with this method is as a student…an old pickle jar
was used…a student tightened the lid down on it and when the
teacher rushed to remove it before the “bomb”, the reacton occured
just as the lid was released and the teacher got a face full. That
was 4 days of miserable barfing and bed rest for the teacher and a
huge scare for everyone present. I was NOT in class.

And, as a note aside…the solutions were simply poured out on the
ground on the banks of a stream. Awful! (This was a private teacher
with a private studio. It was not a school program.

The method shoud not be employed by the uninformed, untrained,
careless, or environmentally thoughtless.

A method where cyaninde eggs are used to clean the surface of