Bombing

Jewelry Discussion
21 
    Anyway, doesn't cyanide, when it is mixed with something,
turn into a gas and isn't that gas what is and was used in gas
chambers?

G’day Iris: (1) any cyanide when mixed with an acid produced
hydrogen cyanide gas which is used in certain American states as
a method of execution.

    And if cyanide is so safe, why are manufactuers trying to
make plating solutions that are cyanide-free? Iris 

  (2) Nobody really said that cyanide(s) are "so safe". What

has been said is that there is no need to regard cyanide usage
with great fear. If used with care and sense cyanides are an
invaluable asset to many industries. However, if any industrial
process can be made safer, then it should be, and indeed, I
believe that such cyanide-free plating solutions are now
available.

The thing to remember is that the word ‘poison’ is synonymous
with ‘too much’. Curare is a deadly poison used by certain
tribes on arrow-points to kill animals, yet it is used in
medicine as a life-saver. Common table salt is used every day
by most people in food, but it has been used to kill when
administered in high concentrations. And so on… Cheers,

       / \
     /  /
   /  /
 /  /__| \      @John_Burgess2
(______ )

At sunny Nelson NZ (in mid-winter, but daphne, narcissus and camellias
are blooming now))

22

Greetings John Burgess, Peter Rowe, et al-

Can we get a concensus of opinion as to the reaction between the
cyanide, peroxide, and water as to what you have remaining after
the bombing? At the jewelry company I work for, we collect the
remains and send them to the refiner with the other suitable
material, although I have also worked at companies where it went
in the drain. I know that there are some serious EPA fines if you
get caught doing this, and as a personal opinion, I don’t think
that anything this potentially dangerous should be disposed of
in such a cavilier manner.

I agree with you about the “pop” Peter, and I also was taught
how to do this and think that it is one of those things that you
develope an eye for, the amounts. Sometimes it will bomb
beautifully, but only like half of the piece or something and
have to be done again. Is it cyanide left or cyanate, or both?
Maybe some unreacted cyanide also? I hear of a non-cyanide
bombing coming from Italy, but Shimon can’t find out anything in
Vicenza- it would be great if it works as well as the cyanide
process, huh? Regards- Rick in Houston, Texas usa

23 
    Can we get a concensus of opinion as to the reaction
between the cyanide, peroxide, and water as to what you have
remaining after the bombing?

G’day; For what it’s worth, my opinion is that the (usually)
gentle ‘explosion’ of bubbles is oxygen in a very reactive state,
derived from the peroxide. Copper and other constituents in the
alloy would oxidise, then dissolve in the cyanide. Some of the
cyanide would also oxidise to cyanate. Carbon dioxide, water,
sodium/potassium carbonates, some steam, would also be generated,
though these latter are harmless (unless you get a great spurt
of steam…!) When the reaction is over the solution would also
contain a very little copper, a very little gold, and a few other
fairly harmless and minute amounts of odds and ends. Cheers,

       / \
     /  /
   /  /
 /  /__| \      @John_Burgess2
(______ )

At sunny Nelson NZ (in mid- winter)

24 
  Can we get a concensus of opinion as to the reaction between
the cyanide, peroxide, and water as to what you have remaining
after the bombing?

I’m not a chemist, remember, so I’m just repeating what I’ve
been told. The peroxide oxidizes the cyanide to cyanate, and in
the process the gold cyanide complexes formed when there was
still free cyanide dissolving gold are converted back to metalic
gold (why the formerly clear solution is brown after the pop).
Whether there remains any free cyanide depends on the amount of
peroxide used, and how long it is allowed to sit together after
the main reaction. I’ve always assumed that some unreacted
cyanide would likely remain. Safer to treat it that way.

   At the jewelry company I work for, we collect the remains
and send them to the refiner with the other suitable material,
although I have also worked at companies where it went in the
drain.

Unless you do only very little, it’s usually worth retaining for
refining. Evaporate the waste down to a sludge to save space.

I know that there are some serious EPA fines if you get caught
doing this, and as a personal opinion, I don't think that
anything this potentially dangerous should be disposed of in
such a cavilier manner.

Agreed. Cavalier is the wrong way to treat this stuff. And the
EPA doesn’t make exceptions based on quantity I’d guess, though
they’ll not likely catch the folks doing one small batch every
month or two.

Nevertheless, it’s appropriate to note that cyanide does indeed
occure naturally in nature, and in SMALL highly diluted amounts,
does little if any harm. The problem comes when every jeweler is
a building full of them has the same attitude with their own
twice weekly bombing process. With all the folks in the complex
doing the same thing, the sewage system is no longer getting
just an occasional trace of the stuff. It’s getting pounds of
cyanide per week. And THAT is not trivial or harmless.

  I hear of a non-cyanide bombing coming from Italy, but Shimon
can't find out anything in Vicenza- it would be great if it
works as well as the cyanide process, huh?

Yeah. but don’t hold your breath. They said the same for the
thiurea based non cyanide electrostrip solutions that PM and
others sell. They do work, but they sure are harder to get to
work well, in my experience. Plus, the sulphur smell is harder
(at least for me) to tolerate than the alkaline one from
bombing. And to date, I’ve not heard of a non cyanide bombing
process. let us know on the list, will you, if you hear more on
it.

Peter Rowe

25

I’ve been working on the bench for 28 years , now and until I
ran into you all, I hadn’t tried a number of things. Night before
last I stopped in to see the hairdressers across the courtyard
and picked up some hydrogen peroxide and tried bombing for the
first time. I’m impressed! I have read a couple of descriptions
tha proved to be untrue, but until now, I could never have known.
To be sure, the process is a weak form of stripping. I suspect
that it will reproduce the crystalline finish that was asked
about yesterday.

Tanx all!

Bruce D. Holmgrain
e-mail: @Bruce_Holmgrain
http://www.goldwerx.nu
phone:: 703-593-4652

26

Is anyone out there familiar with a process called “Bombing”?
I’ve been told that it put’s a nice luster/shine on matte
finished 18k. If any one knows the exact chemicals, and the
procedure involved, I would like to know. Or if any one knows of
another procedure that will provide a bright look to matte
finished gold. Thanks

kevin

27

Bombing requires the use of cyanide! As with plating, something
to be undertaken with the utmost of safety and ventillation
precautions… as an alternative, could you can do a depletion
treatment to put a high gold content layer on the surface of a
piece? I know that it works well on silver, has anyone tried it
on gold?

28

bombing involves heating cyanide dissolved in water (with the
pice to be treated in it) and then adding commercial strength
hydrogen peroxide - it will indeed resemble a bomb. Cyanide is
EXTREMELY nasty stuff. Please don’t mess with this procedure
unless you can put it under a chemical vent hood that’s enclosed
to on all sides with a door to prevent fumes from escaping. Not
stuff I mess with - nice finish aside, it just ain’t worth it.
Get an MSDS sheet on cyanide before you decide whether or not
it’s worth the risks to your health.

29

Kevin, first of all I do not suggest to anyone to do bombing.
It is considerably dangerous. It is done by heating a sodium
cyanide solution, covering the items in a corning ware type pot
and pouring a small amount (1Oz) of hydrogen peroxide 30% into
the solution. You then shake the pot, the solution will foam and
then it will burst. Be sure to hold the lid on tight and don’t
drop the pot when it makes the bursting noise.

It actually leaves a 24k thin layer on the items. Personally I
don’t like the look and will not buy anything that has been
bombed.

If you choose to try it good luck and be careful.

Bill Wismar wismargallery.com

30

HI:

I have used the bombing process many times, Great care must be
taken as the cyanide is rather reactive to acids and if you are
exposed to it with flesh contact you can have the problem I have
because of a poor training and working with people that could
not understand the language. I was trained to control the acid
by pouring cold water into the hydrogen peroxide cyanide and hot
water. when the person did not cool the acid it went throught
the reaction called bombing and went up my arm into my glove, 4
yrs later my liver gave out and it has taken ten years to find
the proof of the damage and then it may be too late. There is
also the thought of what do I do with the spent acid? if you
keep it liquid it can react again if conditions are right. the
only way is to dry it! then you have the transportation to deal
with. If I were you I would invest in a plating system with a
stripping action. God Bless…Ringman John

31

Ringman John, This is the first I’ve heard of cyanide causing
liver damage. I was dealing with cyanide a few years ago and
wasn’t real sure what I was doing, so I read up on all I could
find about safety precautions with cyanide. The things that I
remember are that cyanide doesn’t have a residual effect and
that it flushes from your system in a matter of hours. If
enough is absorbed through skin contact or breathing fumes it
retards your body’s ability to absorb oxygen, enough exposure,
and you can die. I seem to remember that OSHA requires anybody
that uses cyanide to have amylnytrate “poppers” available in
case of cyanide poisoning (for immediate treatment). Oh yea,
and that a cyanide solution can be neutralized with household
bleach. All things considered, it seemed safe enough to work
with in a well ventilated area. The idea of liver failure
resulting from an accident with cyanide adds a new perspective
to an already dangerous chemical. Rick Barnes Fl

32

Hi:
I have done extensive reasearch on the matter in a few days I
should have the answers, the first thing that warning sign say
are afects in ternal organs, the first word on the list is liver.
I have had a reasearch Scientist tell me most definatley it can
and will do that. Most places teach you to have good ventilation,
but alas it was my first opportunity to enter the trade and I was
eager to learn. the room that I worked in had a tiny bath fan for
ventilation and before I stopped them they use to pour the
charged solution thru a filter trap where I found people dumping
pickles and using other acids in the sink and there is always the
chlorine, take off the top and? it was four years after that that
I Started having problems consistant with the diagnosis of the
contamination, sure I was a drinker at the time but I was not an
alcoholic, gave it up ten years ago and not going back there.
Sorry to write a book but just wanted to explain conditions. will
revel what I know when I find out.
Ringman John Henry

33

Hi everyone, I came across the term of ‘bombing’ lately and it is
used in industry for polishing as far as I can comprehend. OK, I
must admit that we are hearing a lot of bombing lately going on and
doing a lot of damage, but this time this type of bombing has a
particular meaning. Could anyone, from the expert section of the
orchidians tell us some useful as to: what bombing is in
finishing industry, what is it’s particular function and what is the
final result? Can the jeweller perform this type of bombing on a
small scale in his workshop?

JOSEPH TANTI
Malta

34

Ah yea the cosmic reaction of hot water, sodium cyanide and, reagent
grade hydrogen peroxide… used for stripping the metals other than
14k gold from a piece of lesser carat. The purpose is to hide
improper casting techniques and give oxidized gold a butter yellow
color. Kinda the proverbial snow job! The technique is best done
outdoors or in a special box vented outside!!! The resulting
vapor is not good for the body and always protect yourself from the
liquid. It can be neutralized by adding baking soda and then drying
the remaining liquid to a powder, I believe this is an inert non
harmful reside but please check to be sure. I had some spilt on me
in 85 and in 90 had liver problems… I believe this was a direct
result of skin and lung contamination… Please be careful and store
the product well away from any acids…Ringman

35

Joseph, Bombing is a chemical means of “polishing” that, wit=
hout
getting specific (for saftey concerns), involves the use of a cyanide
solution to disolve metal(s) from an object then hydrogen peroxide
addition to cause re-depositing the metal(s) onto the object. The
reason I prefer to not go into detail about the technique is that
there will always be the risk of cyanide contamination of the area
surrounding the reaction vessel and the problem of disposal of the
"spent" cyanide solution; which is more often than not still highly
toxic and not truly “spent”. (Seldom does a chemical reation happen
to completion in an under-controlled environment). With the =
advent
of magnetic finishers (also called pin finishers or magnetic pin
tumblers) there is really no need for the bombing technique because
these machines will achieve similar results without the risks and
within a very reasonable time frame (25 minutes or so). The major use
for both methods is to polish in the otherwise inaccessable areas of
the object ( such as in between prongs, in the concave areas inside a
ring, etc.) without risk of detail loss or rounding of edges. Pin
finishers are available in a range of sizes for differing quantity
capacities for respectively differing prices and are available from
most of the better known tool and equiptment suppliers here in the
U.S. (I am not famaliar with their availability abroad). Paul D.
Reilly Colorado Springs, Colorado

36

Bombing is a term used for cleaning castings. Mainly it is used to
remove scales and leftover/clinging investment from the pieces. It
also removes any coloration & makes the pieces brighter.

The pieces to be cleaned are boiled in water and while it is boiling
cyanide is added to the boiling water. You have to do this in a well
ventilated area. You have to avoid the fumes and preferably stand
far and away from all this. A good Ventilation Hood is recommended.

If you check some of the casting books. They may give you better
details

I love Malta the island of the Crusaders. Best of luck

Kenneth

37

Bombing employs the use of concentrated hydrogen peroxide and
potassium or sodium cyanide. All of these compounds are extremely
dangerous singlely or in combination. The reaction that is intended
is that of instanteneously removing oxides and /or copper from the
objects being treated. The resultant precious metal residue has the
effect of making the piece bright as if it had been polished,
although the coloration is modified by virtue of the fact that the
residue is pure precious metal. IT IS NOT RECOMMENDED FOR USE BY THE
SMALL OPERATION ! The risks can be much greater than the benefits
and it is very difficult to control the reaction. Ron at Mills Gem, Los Osos, CA.

38

Hi Joseph, Bombing is a surface reduction technique used for the
purpose of removing cupric oxide, commonly referred to as firescale.

It entails dissolving sodium cyanide in very hot water, dropping
your pieces in, usually in a stainless steel basket, and then adding
industrial grade (35%) hydrogen peroxide. Shake the basket and GET
OUT OF THE WAY before the reaction takes place. The reaction can be
rather violent, sometimes almost explosive, hence the name “bombing”.
Hot water tends to produce a slower, more controlled reaction than
cold water, which can really go off like a small volcano.

Proper chemical resistant apparel and eye and face protection must
be used. Some companies manufacture specially designed “bombing
cabinets” to prevent direc exposure to the process. These are around
$2000. You don’t want to get this on your skin!

I have done a lot of cyanide bombing, and do not recommend doing
this if you are not experienced. Should you require this however,
many plating shops offer bombing services, usually charging by the
pound. Otherwise, thee are many deoxidized alloys which eliminate the
need for this process.

Mark Moretti
Fredericksburg, VA
www.auagcast.com

39

Actually called fire bombing, it covers up porosity in bad castings
and cleans up gold making it look bright. It puts a certain texture
on the metal, like ice on a window pane… Its hot water, sodium
cyanide and hydrogen porxide, very nasty indeed.

Ed Dawson
Maine Master Models
http://www.goldandsilversmithing.com

40 
    Could anyone, from the expert section of the orchidians tell us
some useful as to: what bombing is in finishing
industry, what is it's particular function and what is the final
result? Can the jeweller perform this type of bombing on a small
scale in his workshop?

Hi Joseph, Bombing is a quick chemical strip. It removes and
“substantial” amount of metal from goldwork prior to finishing. It is
useful, in that hidden and very hard to get at surfaces can be
brightened quickly. Some will tell you that bombing will leave a fine
gold surface. Not so. If you ever bomb white gold, you will learn
that in only leaves the surface the color of the true metal.

It can be done with cyanide salts and hydrogen peroxide. Someone on
this list (Daniel Grandi?) pointed out that regular drug store 3%
peroxide works fine if it is heated. I heat a cyanide solution and a
beaker of peroxide in the microwave and combine them in a deep sink to
contain spills. Theory is that the cyanide is broken down. Left over
cyanide can be broken down with household bleach. I also use good
ventilation. Some gold is stripped into solution, so if one is doing
a lot of stripping, it would behove them to save the solutions for
later refining. This process is not like plating in that a truly
substantial amount of gold can be removed. I used to eletrostrip. I
found the found the smell of cyanide even under good ventilation a
little too disturbing. I personally prefer bombing. Then again, I do
it but rarely.

There is a lot of good info on this in the archives. There is also a
lot of bad. Be careful. You be the judge.

Bruce Holmgrain
JACMBJ