I picked up a pad of a new (to me) paper called "Black Block" which I got from the Pendemonium Desk at the Chicago Pen Show last weekend. It is made by Exacompta in France.
By my measurements (with a crappy plastic ruler) the paper measures 214 mm x 287 mm. That makes it a little narrower and longer than standards US letter paper, but doesn't seem to be quite as long or narrow as A4 paper. It seems to be a little closer to US letter, though.
The paper color is more of an off white with a grey grid system on it. It is not a bright white color, in other words.
As far as performance, I am attaching a scan. The only visible feathering that I could significantly detect was with my Sailor Professional Gear using Sailor ink; however, since my nib is scratchy (and, I think needs work), that may be due to a pen defect. Using a loupe, I saw a couple of very focal points of feathering with my Waterman Edson using Waterman Black and my Lamy Studio using Noodler's Iraqi Indigo. However, for all real purposes, there was no significant feathering (in my opinion) with those inks to the naked eye.
I detected no bleed-through to the other side. Writing was not visible when the paper was turned over.
The only real problem was that some inks were a little slow to absorb into the paper. Using my Pilot VP/Pilot Ink, there usually was a 13-15 second delay until the line I drew stopped smudging.
The cost of the paper from the Pendemonium desk was $5 for a 70 sheet pad. This compares to $6.40 for a pad of 50 pages for Levenger's pads (if you buy a pack of 5 for $32).
The cover folds back completely and the pages tear off easily.
Conclusion:
I feel that this is good quality, fountain-pen friendly paper. It has some mild short-time smudging risks. My use will probably be for meeting notes. It is not super-bright, so that may limit its appeal/uses for some people.
Click to view attachment