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Schwerter's solution is quite forgiving to the composition so there are a lot of different recipes on how to prepare it. Here are a couple different.
10g potassium dichromate + 22ml nitric (67-70%) + 7.5ml distilled water
HNO3 + K2Cr2O7 =Schwerter's Silver Test Solution Add 20 grains of potassium dichromate to 30 mL of 35% nitric acid.
Dissolve Potassium Dichromate salt in 8mL of distilled water in a glass container. Add crystals until no more salt will dissolve in the liquid. Add 25mL of 70% Nitric Acid Store in a small bottle.
To test an object a notch is filed into the object, at least so deep that any heavy plating is penetrated. A drop of the solution is applied and the color during the first minute is observed and the mark left by the test. Different alloys and metals will give different colored reactions.
|Alloy / metal||Color after a minute||Color of mark left|
|Pure silver||Bright blood-red||Grayish white|
|.925 silver||Dark red||Dark brown|
|.800 silver||Chocolate brown||Dark brown|
|.500 silver||Green||Dark brown|
|German silver||Dark blue||Light gray Scarcely any|
|Brass||Dark brown||Light brown|
|Zinc||Light chocolate||Steel gray|
|Pure gold||No reaction|
|Platinum||Vandyke brown||No stain|