Art I'm Making: Cyanotype progress

Under the heading of "For What it's Worth": I've been working with the new Christina Z. Anderson Cyanotype book, following a couple of months of experimentation on my own (but with the generous help of another member here who happens to live nearby), focused on classic cyanotype and Arches Platine paper.

Looking at the book, I was very impressed by the work by Eugene Starobinskiy (for example, on page 117). Saying to myself "That's the kind of print I want to make!" and reading his comment saying his best-looking prints have been done on Canson XL Watercolor paper (in a 9 x 12 tablet), I decided to start a new calibration using this paper. It has one huge advantage right off the bat--it's much cheaper than Arches Platine. Also, I don't like that the Arches Platine sheets always come with a sticker on them that ruins part of the already expensive paper. On the downside, the Canson paper is less absorbent, making it a little harder to coat evenly. The blues are slightly different, but hard to characterize. The Arches Platine blue is a little fatter, a little more velvety, but I don't dislike the color of the Canson XL.

The Canson seems to give me a much better range of tones. I used Christine's method to determine a base exposure (I hope I've done it right), based on the information on pages 49-53. I've modified my standard processing slightly, by increasing the acidity of the developing water--going from one tbsp of vinegar/quart to 1 tbsp/500ml, essentially doubling the vinegar--although that's still a comparatively small amount.

The first cyanotype I posted here, and my first real effort was appealing and I put it up with some enthusiasm because I was simply pleased to got an interesting image of any kind (the image of the Transamerica Pyramid in San Francisco). However, the shadows are blocked up in the original print (on the left) and the mid-tones are muddy. Changing to the Canson XL Watercolor paper with the above-noted modification immediately produced a much better result. So, I think I will move forward trying to create a curve for this new paper and development routine. Information about the two prints is given below the images (I hope it's readable). Both were exposed in a beautiful UV-light box my brother made for me. Identical negative. Both classic cyanotype formula from Bostick and Sullivan. Double coated. Naturally, these are images of images, so approximations, but I've made an effort to tweak them so that the on-screen versions look as close as possible to the real prints--although they may look rather different on your monitor. Still, I hope the comparison is of some interest to anyone considering these papers. 

[Having posted this on the Facebook cyanotype page I unexpectedly triggered a long thread with many people much more experience than me. They've convinced me that the Canson is not a good choice for serious work because it has buffers in it that react badly with cyanotype chemistry over time. Although it works very well, it's not archival. Back to the Arches Platine.]