Can vitex salt pickle remove fire scale

[Muggins2003]

Hi,

I am a beginner and have made a silver ring which after polishing has black cloudy marks which I now know is fire scale.
This was removed by an acid pickle previously but returned when I repolished the piece.

Would vitex salt pickle remove the fire scale without the need for further polishing? Or is the acidic solution better?

Thanks

[Dennis]

Hi,
Firescale is due to the formation of a cupric oxide layer and some of the traditional ways to deal with this are:

1.A brief dip in nitric acid.
2.Use of strong abrasives such as wet and dry, or a green Scotchbrite wheel, or a brush and wet pumice on a polishing lathe.
3. Depletion gilding in pickle, or simply silver plating.
4. Leaving with a satin finish when it will hardly show.
When removing it, firescale is more easily seen in subdued light, or through tracing paper, or baking parchment.

Prevention consists of:
1. Not prolonging heating and using a bushy flame.
2. Applying a flux all over to prevent oxidation, such as Argotec, or a saturated solution of boric acid in meths. (but keep the bottle well away from naked flame).
Dennis.

[Goldsmith]

If the ring is thick enough, why not just polish off the firescale, using a bristle brush or a calico mop on a bench polisher, using Tripoli compound applied in small doses to the brush or mop. A little bit of pressure against the mop and the firescale soon goes, then a finish polish with a soft swansdown mop and rouge compound.
James

[Patstone]

Hi Dennis, I have had the same problem with some of mine, will Household ammonia help, I have found when you clean with red rouge it doesnt come off easily and if you put it in some ammonia for a while it comes off easy. Pat

[Dennis]

Hi Pat, How are you today? The answer to the firescale question is no, you can wear it away with abrasives, but it is exceedingly tough. Also it is difficult to see whether any remains, until you have a mirror finish again.

Alternatively you can dissolve it with nitric acid, try depletion gilding, or just give up and have it plated.

Depletion gilding of sterling silver consist of heating to dull red five or more times and each time dropping it into your pickle. This dissolves the surface copper leaving a very thin layer of fine silver, suitable for objects with little wear. Regards, Dennis.