Bill;

The original patents also refer to "salting out" using Calcium Sulfate or Magnesium Sulfate. I did this in early precipitations, but when I had to develop a method to teach, I decided on ISO washing with Phthaled gelatin or noodle washing.

You can add a huge dose of these inert salts and the gelatin will curdle. Then you remove the curd and rinse with ice cold distilled water. Afterwards, you add the desired amount of water and then warm until the entire thing melts.

This leaves an inevitable amount of sulfate salts in the coating but does work. To this day, Kodak Park has piped into labs a "Sweet Water" which is Calcium Sulfate for washing. You see, they could combine the salt treatment with washing repeatedly and then a final water rinse.

The problem is that measuring the final pAg becomes complicated due to the inert (but not really inert) salts present. It was used though until ISO washing was invented.

PE