bombing help!

[lopez]

does anybody still cyanide bomb???? I always seem to get a 'hit and miss' result when bombing higher carat gold; if I bomb a polished yellow gold item should the result be a highly polished item with a richer colour or a matt finish with a rich colour?? I always get the later.....help!

[Kwant]

I can't help, but the title gave me a chuckle to think of black hats worldwide flagging this thread.

[Di Sandland]

I can't help, but the title gave me a chuckle to think of black hats worldwide flagging this thread.

I'm surprised MI6 haven't already closed us down!

[Dennis]

Go on Lopez, don't keep us in suspense: what the hell is a cyanide bomb?

[Julian]

Go on Lopez, don't keep us in suspense: what the hell is a cyanide bomb?

I could not wait I found this on Google (waiting for my door bell to ring! )


from http://goldrefiningforum.com:

"Jewelers used bombing solution to polish the gold because it uniformly removes a thin layer of metal from all exposed surfaces. By bombing before polishing the jeweler was able to retain a little more of the customers gold than by polishing alone.

Classically bombing is a mixture of potassium cyanide and hydrogen peroxide in water and the concentration of cyanide is high.

To recover the gold raise the pH to 12 with caustic soda and sprinkle in fine mesh powdered zinc dust, roughly 2 ounces for every ounce of gold you expect to recover. The gold will drop out pretty quickly and you will see the mud in solution go from brown to grey when it is complete. Filter the solids and you will have a mixture of zinc dust and precipitated gold. Rinse this well and if possible add hot water and boil it for a while to expel any cyanide. You can dissolve the excess zinc using HCl but be careful and do it upwind or in a hood to make sure you don't breathe in any fumes when you acidify what may contain residual cyanide. "

Julian

[Dennis]

Thanks for that Julian, but I'd rather be upwind of a pride of lions. Unless you are thinking of casting off this mortal coil, give it a miss. Dennis.

[Goldsmith]

In my younger days when I was an apprentice, my master used to what he called "Gold Colouring" some now call this depletion gilding. This was a method of suspending 18ct gold items in a boiling chemical mixture of water, potassium nitrate, alum and salt. The items were suspended in the froth of this boiling chemical mixture for a few seconds at a time and the chemical's reaction was to eat away the gold alloys from the top layer of the 18ct gold and giving a rich pure gold 24ct colour.

Does this process achieve the same effect as your cyanide bombing?

James

[Di Sandland]

certainly sounds less scary James!

[lopez]

Thanks all! I guess cyanide bombing is not that popular! But is was good to hear all the coments. On heating a mixture of potassium cyanide and hydrogen peroxide the gold items are placed in a bomb proof container and the mixture explodes ie, bomb! The items get coated is a fine gold layer which helps hide the different solder colours. The down side is that the fumes (cyanide) can leave you meeting your creator quicker than expected so you tend to become aware of the almond smell and run for cover! Luckily the wind on the North Cornwall coast is always at hand. Keep smiling or die trying!

[Julian]

I just stumbled acress this ;

http://www.balco.co.uk/polishing_bombing.shtm