I bought 16 coins - a mix of (advertised) premium, desert and low quality coins.

I soaked all in distilled water and used a small soft brush or blunted toothpick as required.

The low quality coins all turned out to be blank discs or unattributable. Unfortunate but good practice. The desert coins i wouldnt soak again, the sandy patina came off immediately but the detail became more difficult (even under a jewellers microscope) to see and weren’t able to attributed. I learned all the same.

Of the 16 coins, 7 had visible detail and 3 could be attributed. I look forward to buying some more and having better luck.