It was DOP pt.pd. Yeah I agree Fabriano Artistico has the hardest shell of sizing I have ever had to deal with. It is a watercolor paper that was created for watercolor artists to keep pushing their liquid water color around with brushes and the sizing was designed for the artist to work without the paper absorbing and stopping the this creative action unlike printmaking papers that has little size for the etching presses.
I work with humidity quite a bit and actually put the paper into a humidity box at 80% for ten minutes before exposure. I found this injected for some/not all increases the dMax but will also make it a bit harder to clear. With your SA method we are literally stripping out all of the papers prepared sizing and starting with a pristine sheet of rag paper. It is more difficult to clear in that there is no sizing to prevent the emulsion into settling deep within the paper fibers.
In my clearing I do a 3 minute development – water wash dump (no reason to have the first clearing bath work so hard) and then do 4% muratic acid – EDTA – Citric acid – sodium sulfite all at 5 minutes each and it works well. The sodium sulphite is just two minutes. I like this acid – sulphite – acid attack.
Best - Stan