It’s one of the essential components in watercolor painting. And believe me, when you really get going, you’re going to use a lot of it !
I remember when I started watercolor painting, I went to a huge art store near to where I live. They had an amazing choice of watercolor paper. All kinds of different sizes and formats.
The choice was mind-boggling !
So I asked the store assistant for help.
But when she asked me “do you want cold press or hot press” ? I have to admit I was stuck.
So What is the difference between hot and cold press watercolor paper?
In a nutshell, the terms “hot press” and “cold press” refer to the paper’s surface finish or texture. Cold pressed paper has a slightly bumpy, textured surface. But hot pressed paper has a smooth surface finish.
You will also hear artists talking about the tooth of the paper. For example, hot press paper has almost no tooth, but cold press paper has a more pronounced tooth.
There is another category of watercolor paper called rough (labeled R). This paper has a highly textured surface and a very pronounced tooth. This type of paper tends to be less popular because brush strokes are more difficult to control and the texture is accentuated when the paint dries.
Why should you care what kind of paper you use ?
Watercolor paper is a little more complicated than just “rough or smooth”.
It would be a mistake to attach little importance to your choice of paper. It actually has an effect on the results you obtain when painting, and different types of paper will react differently to paint.
There’s only one way to find out which type of paper suits you best, and that is to experiment.
With that being said, understanding the different characteristics of watercolor paper will go a long way to help you choose your paper confidently.
What are the differences between cold press and hot press watercolor paper ?
Cold press paper characteristics:
Cold press watercolor paper is labelled CP (or in england NOT meaning not hot pressed).
The term “cold press” originates from the process used to manufacture the paper.
A sheet of paper is basically a thin mat of tangled cellulose fibers. To make cold pressed paper, sheets of cellulose pulp are pressed through felt covered metal rollers at cold temperature - hence the designation “cold press”. The felt rollers and the drying process used contribute to the bumpy texture of this type of paper.
This is probably the most popular type of watercolor paper.
It’s known to be relatively easy to use, and is well adapted to almost any style of watercolor painting - hence it’s popularity.
Cold press paper is more absorbent than hot press. This means you have slightly less time to move the paint around the surface before the pigments fix to the paper.
Colors are less rich and slightly paler when using cold press paper. This is probably due to the way light reflects off the paper (after all, the white paper is the source of light for a watercolor painting). The indentations on the bumpy surface of cold pressed paper scatter reflected light, thus producing softer diffused colors.
This type of paper is dimensionally stable when wet.
It also accepts a certain amount of corrections or lifting off (where you remove some of the paint pigments off the paper).
The texture of the paper itself adds to the aesthetic appeal of the final painting.
Paint pigments settle and dry in the grooves and less on the ridges of the paper, revealing the texture of the paper, and contributing to the appearance of the finished artwork.
Hot press paper characteristics:
Hot press watercolor paper is labeled as HP.
Again, the term “hot press” refers to the method of fabrication used for this type of watercolor paper. Traditionally, with this method, the sheets are pressed at high pressure between smooth heated rollers - hence “hot pressed”.
This technique also contributes to the smooth surface finish of the paper.
This type of paper is popular for precise styles of watercolor work because it’s good at showing a high level of brush detail. This paper is also well adapted to styles that want to accentuate the watery irregularities of the paint and for combining pen and ink with watercolor. This makes the paper good for glazing (successive layers of dried paint) although when there are many layers of paint the surface can get overloaded quickly. This type of paper tends not to hold the pigment in place as well as cold pressed.
Because of the higher density of the paper fibers, hot press paper is less absorbent giving you more time to play with the paint before it dries.
Pigment colors are more vivid with hot press paper, probably because light is reflected directly off the flat white surface of the paper, producing brighter colors.
Lifting off paint is easy with this type of paper even when dry.
A quick comparison between hot and cold press paper
Hot press paper:
Cold press paper:
The quality of watercolor paper
There are some other important factors you need to keep in mind to help you judge the quality of the watercolor paper you choose. The quality of the paper affects the way that paint handles on the surface and the smoothness of your brush strokes.
A paper’s quality is dependent on its composition and the manufacturing process used to make it.
The best quality of paper to use for watercolor painting is 100% cotton, acid free, and pH neutral.
As mentioned earlier, paper is made up of cellulose fibers. Today, the more common sources of cellulose are wood, cotton and linen, with wood pulp being the most used.
However, wood is not a good source of cellulose for watercolor paper.
The biggest threat to a paper’s durability is acid. Acidic papers such as those made from wood pulp can become brittle and discolor in a very short time.
Wood cellulose causes acidification over time so wood pulp papers should generally be avoided for artistic use.
Cotton fibers are strong and flexible and they are naturally white and acid free. Cotton cellulose is also up to 10 times stronger than wood cellulose.
This makes cotton an ideal substance for watercolor artist grade paper.
How is watercolor paper made?
The manufacturing process used also affects the quality of the paper. As you can imagine, mass produced automated paper production is is less expensive and lower quality than handmade watercolor paper.
Handmade watercolor paper
This is the highest quality manufacturing process and the strongest type of paper.
The strength comes from the fabrication process. The mold used for making paper by hand has two parts - a wooden frame with a wire mesh stretched across it (the mold) and a second frame placed on top of the mold (called a deckle).
The mold is basically like a big sieve which is dipped into a vat of cellulose pulp. The mold is then moved up and down and side to side. This hand spreading results in the paper fibers being completely interlaced, making the final paper very strong.
The deckle is then placed on top of the mold. This keeps the wet pulp within the bounds of the wire mold and helps control the finished size of the paper sheet.
Handmade watercolor paper is recognisable by it deckle edges which are result of this paper making process. You can tell handmade paper because all four sides of the paper have a deckled effect.
Note that some manufacturers add deckle edges to industrially made papers. This is known as a faux deckle edge.
Moldmade watercolor paper
Moldmade paper is the next best quality manufacturing method.
With this type of method, the wire mesh is in the form of a cylinder which turns at slow speed. The pulp is poured over the mesh and the sheet of pulp is deposited onto a moving belt of felt.
With this method the the cellulose fibers a fairly randomly interwoven resulting in reasonably good paper strength.
Moldmade paper is recognisable by it’s two deckle edges (the very long sheets produced by the machine are cut into individual sheets leaving two cut edges and two deckle edges).
Machinemade watercolor paper
This is the lowest quality production method. Cellulose pulp is injected into a machine which has a wire mesh sheet, then sandwiched between two layers of felt. These machines produce a continuous roll of paper at very high speed.
With this process the cellulose fibers are not very well interlaced and tend to be aligned in one direction, resulting in paper which has less strength.
What is the GSM of watercolor paper?
As you probably know, watercolor paper is available in different thicknesses. Thickness is indicated by the weight of the paper. The weight is labeled as gsm or g/m2 or lb.
GSM refers to grams per square meter and is a more recent and more accurate measure of the weight and thickness of watercolor paper. You will also often see an imperial measurement equivalent in lb or pounds per ream.
(the old imperial measurement is inaccurate, because from one manufacturer to another, the size of the sheets in a ream could differ. A ream is 500 sheets, but the size of the sheets could be larger or smaller. So the weight of a ream isn’t a dependable measure).
My advice is to stick to GSM when comparing paper and forget the traditional pounds per ream measurement.
The thickness of watercolor paper is important because it has an influence on how much the paper buckles when wet and how quickly water is absorbed and dries.
Thicknesses can vary from one brand to another, but the more common weights are as below:
What’s the best paper for watercolor painting?
It’s up to you to find which paper suits you best, but if you stick to the following guidelines you should be OK !
The ideal weight for watercolor paper seems to be 300 gsm. Anything lighter will buckle easily when wet, and can tear when using a wet on wet technique. Thicker paper also tends to absorb quicker and modify the water cycle when working wet on wet. Using thicker paper means you can avoid having to stretch the paper to prevent it from buckling. However, the thicker the paper, the more expensive it becomes !
Remember to use 100% cotton, acid free paper for your final paintings. It’s fine to use lower grade papers mixed with wood cellulose, for anything else.
Most watercolor paper is moldmade, so the quality is good. If the paper is machinemade, that’s fine - but you should probably reserve this kind of paper for sketchbooks and watercolor studies. From time to time I like to buy some handmade paper for the sheer pleasure of it !
What are you waiting for ? Go use some watercolor paper !
Of course paper is just one of the basic necessities for painting - read more about which supplies you need for the best watercolor experience.