DENTAL ACID TESTING IS INEFFECTIVE.
Acid testing is a common way to distinguish how much gold is present in a simple jewelry alloy. This method is inappropriate for dental alloys because the composition is more complicated. For example, Platinum and Chrome will react to an acid test in the same way. They both will have a neutral reaction. Platinum is a valuable precious metal, and chromium cobalt is an inexpensive base metal.
Any acid test on an alloy containing Platinum Group Metals will be thrown off by this typical reaction. Platinum is found in older crowns, but Palladium also responds in this way. Other base metals will convolute the acid test and there’s simply no telling how without an assay (analysis) .
The alloys need to be refined so that an assay can be conducted. This is the only sure way to know how much of each precious metal you’ve got.