Watercolour paper classification

Watercolour papers can be sorted by couple most important criteria. Those are in my opinion main points you could take a look at before buying paper at artshop (or even online).

Paper weight 
Generally for watercolours – the higher is it the better paper works with watercolours. Paper weight is weight of 1m² of this paper which simply can indicate how thick paper is (although it’s not always perfect reply, paper can be pressed into thinner form and still have same paper weight). Usually watercolourists use paper with paper weight higher than 300 g/m² but personally all my favourite papers’ weight is rather closer to 250 g/m².  Best papers are the ones with 500g/m² or higher but 300 g/m² is usually most affordable.

Texture 
Watercolour papers come in 3 different textures: Hot press, cold press and rough. There are some papers that have texture pressed in them only on side of it and as far as I tried them they weren’t the ones I would recommend. If you know such paper and it works for you though then you shouldn’t worry about that.

• Hot press (Smooth, Satiné etc) – has very smooth and flat surface, very similar to some cartridge papers. Works really well with water solvable coloured pencils as well as watercolours – lower shelf types can absorb colour in too fast making it very hard and sometimes even impossible to blend. Its’ smooth surface eliminates bit rough effect that watercolours often have (which might be good or bad dependable on your preferences).
• Cold press (Grain Fin,  NOT etc) – textured, but usually only slightly bumpy. The texture allows paint to settle into the texture pockets or sit on top and skip over the pockets, creating some different painting technique options. It’s easier to blend colours on such paper and it gives this traditional rough edge look that watercolours you see around often have. It’s probably most popular and easy to get type of textures which gives you probably biggest choice in those papers. They are very comfy to use and often they are cheapest.
• Rough – has an even bumpier surface than cold press. This surface is good for exaggerated rough texture techniques. It’s less popular than cold pressed but works in similar way. Gives your work rough beautiful touch. They are harder to obtain and I would recommend it to rather more experienced watercolourists.

Fibres

In watercolour papers are usually 3 types of fibres – cellulose (fibres acquired from wood), cotton rag and bamboo. Last type isn’t often but for sure is worth mentioning. Paper from cellulose fibres is most easy to get and is the cheapest.  It’s also possible to get mixed fibres papers. Cotton fibres paper is the most expensive but it doesn’t deform easily after contact with water (even extensive one). It generally has more elegant feeling to it. Papers with bamboo fibres has similar qualities to cotton fibres but is more rough to touch (even though the surface is usually pressed flat). 

This is mostly some general information before publishing overview about watercolour papers : )