I stumbled on a vast richness of beautiful vintage source material for early 20th Century Japanese brushes and came across two compiled volumes of a Japanese art and design magazine called Shin-Bijutsukai. Basically, it was a magazine that featured nothing but different artist's illustration work. You can find the scans here: [link] . All the material is public domain as they were published in 1901.
What was interesting was the scan technique. When I used Adobe Acrobat Pro to extract the images and left the setting as 'export to tiff' by mistake, it gave me two files for each scanned page - one containing mostly fields of colour, and the other giving me the clean dark outlines. The colour layer file was much lower res and quite lossy, but the line art layer was almost 580 dpi and very crisp and clean.
I gave a little thought to this and did some experimentation, and realized I could create brushes from this - a kind of a/b pair set that would overlay each other and allow for a beautiful two layer brush stamp.
I remember in the 80's hearing someone talk about the idea of using feedback (an accidental byproduct of amplified sound) as a texture in itself. This was a little the same. The idiosyncrasies of the scanning method, the compression strategies, and the strange way that Acrobat extracts images have resulted in some beautiful design possibilities.
So, I made two sets your delectation: