JW -- one usually wants sizing in the paper...Larry is the first person I have heard of using unsized paper, on purpose anyway. Processes using a coating of liquids (platinum, van Dyke, cyanotypes, etc) want the chemicals to soak in, but not too far in. The image is suppose to form in the upper layer of the paper -- not deep inside it. At least with cyanotype, the chemicals are relatively cheap. To have an unsized paper soak up platinum salts would hurt the old pocketbook!:o