When talking about Strathmore, I should first mention their methodology of using numbers for grading products. The products they have range from series 100 to 500 where 500 represents their very best, their top of the line paper.
For this particular 400 series watercolour journal, Strathmore has used 300gsm watercolour paper. Sketchbooks with 300gsm paper are uncommon but very much appreciated. Because the paper is thick, this sketchbook has only 48 pages. The surface is coldpress with a slight texture that works well with watercolour as well as pen and pencil.
One important thing to note is this sketchbook is available in paperback and hardcover versions. The paperback has some sort of smooth faux leather-like feel to the surface. It seems quite durable as well because I've pulled out and put this sketchbook in my sketching bag countless times and there are no signs of dog-eared pages or of the edges fraying. The hardcover version is even more durable.
I would recommend getting the hardcover because it's easier to draw against a hard back. The paperback is best used on a table and hence it's not as suitable for use when sketching outdoors where you may not have access to a hard surface to draw on. It's great that Strathmore has both paperback and hardcover. Price difference between the two isn't too much.
The pages are bound together by stitching and they can open flat for drawing across the gutter. The stitching looks and feels durable.
The coldpress watercolour paper has consistent texture on both pages. It does not contain any cotton, and is a wood based sheet, but it is acid free. The 500 Series Mixed Media on the other hand is 100% cotton. The paper handles water well enough but not good enough for wet on wet. There's no warping even with heavy washes or multiple washes, but you do have to control the amount of water used because too much water will just glide on the surface.
The paper is white and watercolours appear brilliant and vibrant when dried.
The only downside of the sketchbook is for some reason, it does not work well with Noodler's ink. By that, I mean the slow drying Noodler's ink dries even more slowly on this paper. Even when the ink looks dry, it may not actually be dry. I've several black and white sketches that were damaged by smudges because the ink wasn't dry. I've also used Noodler's ink on the Global Art Materials watercolour sketchbook and there were no problems with smudging. So the combination of Noodler's ink and Strathmore 400 Series watercolour paper don't work.
Overall, this is a fantastic watercolour sketchbook that's well worth the money. There's just that little quirk with Noodler's ink which isn't an issue if you use other ink. The paper is satisfyingly thick and handles watercolours beautifully.
Here are some sketches from the sketchbook.