I first heard of this product when Catherine Beale came to my art group to do a demo. She uses these boards for her 'gravity painting' technique. Several of the group have since tried them and indeed bought blocks. They come in A3 size, there is also a smaller version, with 10 boards costing £15- £19, depending where you buy them and what offers are current. The price is similar for a single sheet in a 20 sheet Waterford block.
The boards are thick and absolutely rigid. The surface has a slight tooth, somewhere between fine grain and not. It struck me they might be worth trying on portraits. They come as already said in a thick block of ten boards.
'Fish Hawk' Cayuse Indian 1905 A3 Watercolour Board.
This is the result. I actually used only two or three colours, the main ones being Perylene Maroon and Ultramarine Blue. There is a little Burnt Umber and Raw Sienna but the figure is mainly the first two colours with some Transparent Brown (Schmincke PBr41) to darken the blue. It's early days yet but I shall definitely persevere and see where (or if!) it leads me. It is very monochrome but I like it - not perfect as my stuff never is but there you are.
The brushes above are synthetic mixes apart from the white Neef that is pure synthetic. Neef are what Robert Wade uses.The redoubtable Zvonimir recently pointed out that sables were damaged quite easily on rough hard surfaces, papers like Arches or Khadi. He recommended synthetic brushes for those papers. I have quite a collection of sables but also the three above, not previously used. I'm also concerned at the escalating and eye watering prices of sable brushes, especially when you get past size 4. So as well as the board I tried out the Da Vinci 5530 Cosmotop B size 8 and the Rosemary 401 size 10. I used a smaller older sable brush for the smallest detail. The Da Vinci brush is a mixture of animal hairs with a small amount of synthetic. Viktoria Prischedko and Piet Lap both use these Da Vinci brushes in a range of sizes and types, not just rounds. Jacksons current price for the size 8 is £11.00. Rosemary is a mixture of red sable and synthetic, and offers two round series (plus other types) 401 and 402. The size 10 401 is £10.40p or £10.70p with a longer handle., the 402, a longer slimmer brush, £11.25p. Size 8 is only £7.95p.
To be honest I don't see much difference in the above result - if any - between these and the dearest sables I use. Possibly that's just me so don't take it as gospel. How they will last is something that only time will tell. I won't be buying any more expensive sables as I have plenty. There are now a mass of new synthetic brushes on the market and possibly they are finally living up to the claims that they 'emulate sable'. Otherwise try sable/synthetic mixes - the best of both worlds.
As said these are provisional comments based on just a little experience. I will post again when I've further to report.