Here's the review of the Marbleous watercolour sketchbook I received from Wiltfried in Amsterdam during the Urban Sketchers Symposium a few months ago.
Wiltfried Pathuis is an illustrator and urban sketcher from The Netherlands and he makes some sketchbooks to sell. These are customised handmade sketchbooks with unique covers and watercolour paper you can choose.
The sketchbook I received was a hardcover sketchbook with 240gsm watercolour paper. Corners are rounded off.
The pages can be laid completely flat and the binding looks good. A bookmark ribbon is included.
However I'm not sure about how durable the stitching is. A split developed between the first and second signatures (pieces of paper that are folded as a group). The 2nd and 3rd signatures look alright.
The paper's brand is unknown. All I can say is the paper can handle water but it's not the 100% cotton watercolour paper so don't expect too much. It actually reminds me of the paper in some Stillman and Birn sketchbooks.
The paper is coldpress but the texture is more like fine grain cartridge drawing paper. Pen and ink works well on it.
Downside of the paper, or downside of non-cotton watercolour paper, is paint won't diffuse/move much when you use wet on wet techniques. For example when you charge in another colour into a wet wash/surface, the colours would just spread very slightly and stop. With good 100% cotton watercolour paper, you can expect the paint to diffuse softly. In other words, the paint, water and paper are doing the work for you. So for this paper, to get those soft colour blends, you have to move and mix those colours yourself with your brush manually.
Layering doesn't seem to work too well. You can definitely layer but I don't recommend using more than 2 layers. The paper surface is actually durable enough to handle more layers but the texture is not rough enough to hold more layers of paint.
In other words, this sketchbook is good for quick pen and ink sketches but not suitable for multi-layer full paintings.
Anyway, these custom made sketchbooks, which means if you want better paper, you just have to tell Wiltfried to make the sketchbooks with those paper.