The last time I used this paper for platinum/palladium/Ziatype printing, I got these weird discolored blotches in the image area. This time, in planning for doing some gum over printing, I decided to try a pre-acidification bath. I had a bottle of Oxalic Acid sitting around the house, so I mixed up a batch of 5% Oxalic Acid, and ran my paper through a 5 minute bath, followed by a brief warm water rinse. So far, so good - no impact on the sizing of the paper, and my first Ziatype came out flawlessly. Now it's on to dry the print and give a gum layer a try!