Recommendation

Let’s just get right to it. If you are a beginner, and you just want to know what you should buy…

Summary

Watercolor paper is hands-down the most critical supply when it comes to watercolor. You can get away with inexpensive brushes, or even inexpensive paints, but nothing can make up for high-quality paper. The flat washes, smooth gradients, and bright colors you can get with artist-grade paper simply aren’t possible with cheap paper. In this post, I explain why the paper matters, what kinds of paper are available, and help explain some of the confusing terms you’ll come across when shopping for watercolor paper.

What is Cellulose and Why is it Important?

100% of paintings are painted on something. In the art world, the thing you paint on is called “the support.” Oil and acrylic painters typically use canvas or wood boards as a support. Mural painters use bedroom or dining room walls. Banksy uses buildings, roads, curbs and sidewalks… you get the idea. When we paint with watercolor, our support is paper.

Paper is made by mashing plant material into a pulp, boiling it, pressing it flat, and letting it dry. At a microscopic level, paper is really nothing more than a mat of tangled fiberous plant cells.

Almost all plant cells have cell walls, and almost all cell walls contain a natural polymer called cellulose. The amount of cellulose in a cell wall differs depending on the plant. For example, wood cell walls have 30-50% cellulose, whereas cotton cell walls can be as much as 95% cellulose.

Cellulose is important to plants because it gives them their unique property of being simultaneously rigid and flexible. Because paper is made from plants, it benefits from these structural properties. Cellulose is also important to plants because because it doesn’t dissolve in water. While it doesn’t dissolve in water, it does break down when exposed to acid, and actually produces more acid in the process. This creates a chain reaction of degredation. An acid turns cellulose into acid, which turns neighboring cellulose into acid, and on and on. If this chain reaction occurs in paper, the paper will become brittle and eventually turn to dust. (If you have ever held old newspaper, you know what I’m talking about.)

Wood Pulp Paper

Because wood is so abundant, and has so much cellulose, it is used to make most of the world’s paper. Unfortunately, wood cells have a secondary cell wall that wall contains a high concentration of a compound called lignin. Lignin becomes acidic when exposed to oxygen – and that’s bad news for cellulose. When paper is made from wood, that lignin gets mixed up with the cellulose, and triggers the chain reaction as the lignin oxidizes. Newsprint paper, which artists often use to practice drawing, is made this way. The manufacturer does nothing to counteract acidification which makes the paper less expensive, but also guarantees it will self destruct over time.

To protect wood pulp paper from self-destructing, manufacturers have to do something about the lignin. They can remove as much as possible in a number of ways. They can strip the bark (which has more lignin than internal wood). But stripping the bark means less overall material is available for production, and the resulting product is more expensive. They can also run the pulp through chemical baths that dissolve lignin, but they can’t remove all of it. To protect paper from any remaining lignin or future acidification, they can add chemicals to neutralize the pulp. The resulting acid-free pulp is used to make archival paper that can last for centuries. This acid-free paper is great for drawing, it is strong, relatively inexpensive, and stable.

Unfortunately for us watercolorists, lignin is also water-repellant. Because manufacturers can’t remove all of the lignin in wood pulp, the paper made from it is riddled with water-resistant fibers. There are a number of factors that can make paper unqualified for use in watercolor paintings (fiber length, impurities, sizing application, residual impurities etc.). Most of these could be addressed even when producing wood pulp paper, but no matter how perfectly that paper is made, it will always contain lignin. When you paint on paper that contains a mixture of lignin and cellulose, the water that carries your pigment will absorb readily into the cellulose fibers and deposit the color there, but it will run off of the lignin, leaving you with uneven, streaky washes.

Cotton / Rag Paper

This is why watercolorists turn to 100% cotton paper (sometimes called rag paper). The cell walls in cotton plants contain 95% cellulose, even more than wood. Cotton fibers are also longer than wood fibers, more flexible, whiter, and more absorbent. This results in paper that is stronger, whiter, and naturally stands up better to water. Most importantly for us, cotton cells contain virtually no lignin. So not only is cotton paper structurally preferable to wood pulp paper, it is also more absorbent, which makes it better suited for our purposes.

Cotton is less abundant than wood, making cotton paper more expensive. Some manufacturers try to reduce costs by selling “cotton paper” that is made from a blend of cotton and wood pulp. This paper is less expensive than 100% cotton paper, but it contains lignin – and you’ll fight it. For that reason it is important to look for 100% cotton paper.

As a side note, you’ll find a handful of manufacturers that produce paper made from a cotton/linen blend. Linen has many of the same qualities as cotton. It’s a bit less absorbent, but also stronger. Paper made from a cotton/linen blend is going to work just fine for your watercolor painting. So, I recommend buying 100% cotton paper because (unscrupulous manufacturers on Amazon aside) you know what you’re getting. That said, paper made from a cotton/linen blend is absolutely acceptable, if not preferable. The biggest thing you want to be sure of is that there is no wood pulp involved. If you aren’t sure, it never hurts to buy a few sheets and try it out. Worst case scenario, its crap and you use it for practice.

Sizing

When manufacturers make watercolor paper, they impregnate the pulp and/or the finished paper with a gelatin or starch substance known as sizing. This substance makes the paper slightly less absorbent, making it easier to apply paint smoothly. Instead of immediately sucking the water deep into the cotton fibers, sizing slows down how quickly water gets absorbed into the fibers. This makes it easier to lay down smooth washes by giving the pigments in paint a chance to spread out evenly before the water gets sucked into the fibers and deposits color on the way down. Without sizing, paint would get sucked into the cotton fibers rapidly, leading to pools of concentrated color and dull washes. Unlike lignin, sizing isn’t water resistant, it will absorb water. It just absorbs water a little more slowly than cotton, leading to smooth washes.

Some manufacturers apply sizing to the surface of the paper after it is dried. Others add sizing to the pulp itself leading to paper that is empregnated with sizing throughout. Others (like Arches) apply sizing to the pulp, and again to the surface once the paper has dried.

Because sizing is water soluble, it is also susceptible to damage in humid environments, or when exposed to detergents. If you soak paper to stretch it, be sure the sink or tub you use has been rinsed thoroughly to ensure no soap is present. If you buy paper in bulk (and I suggest you do) it needs to be stored in a place where it won’t be exposed to excess heat or humidity. Any of these factors can cause the sizing to break.

When you paint on paper with broken sizing, you’ll notice speckles that don’t accept the paint. They sell products to fix broken sizing (Holbein Multi Size) but I have never used it, so I can’t comment on how well it works. I haven’t seen this happen very often, but it will happen. If you notice that the sizing on your paper has broken, just set the paper aside, and save it for practice.

Sizing is often described as “hard” or “soft.” The harder a sizing is, the longer it will take for water to absorb into the fibers. Some watercolorists like very hard sizing, others like softer sizing. Neither is inherintly better than the other, it just depends on your preference and level of familiarity. As you paint more, you’ll begin to get a feel for these differences, and eventually notice that some papers feel pillowy, while others feel more glossy. It’s a very subtle difference, but you’ll begin to notice it after a while.

Paper Weight

You may have noticed watercolor paper is described by its weight. You’ll see 140 lb / 300 gsm or 300 lb / 640 gsm on the package. The imperial (lbs) number tells you how much a ream (500 sheets) of full sized paper (22″ x 30″) would weigh. The metric number tells you how much a square meter of that paper would weigh. Weight is important in watercolor because thicker papers resist buckling when wet, and hold up better over long periods of time.

Buckling

Buckling occurs in paper because the fibers swell as they absorb water. If you tape your paper down to a board when the paper is dry, all the fibers are tightly connected and as thin as they will get. When you introduce water, those fibers swell, increasing the overall size of the paper. Because the paper is taped down, it cannot grow laterally or vertically, and it buckles. There are a few ways to combat buckling.

Floating

You can just not tape the paper to the board. I call this “floating.” When the paper is not taped to the board, it can grow laterally and vertically without constraint, and it won’t buckle. However, even floating can cause buckling. If you only add water to a small portion of the paper (and you will need to), the dry fibers around that spot will constrain the fibers in the wet spot. The fibers in the wet spot won’t be able to grow unconstrained, and will buckle if the wet spot is large enough. So even floated paper will buckle. It will buckle a lot less, and since this is the easiest way to combat buckling, it is the preferred solution for a lot of artists.

For me, the biggest drawback to floating is that the back side of your painting will get ruined. The board you are using will get pigment on it, and that pigment will stain the back of the paper. This does nothing to the painting on the front, so if you don’t care about the back of the paper this is completely fine. But I almost always use the back side of the paper for another painting. I still see myself as a learner, and paper is expensive. So, I paint on the back of the paper whenever I can. Watercolor paper is thick enough that you won’t hurt the painting on the other side unless you use an absolute ton of water – in which case the painting on the front will be sitting in a puddle, and the applied paint will smear. But if you aren’t happy with the painting on the front, who cares if it smears? Right?

Stretching

Another way to combat buckling is to stretch the paper. If you wet the paper thoroughly, and don’t contstrain it, the paper will swell. If you tape or staple it to a board while it is at this largest size, and then let it dry, the fibers will stretch like a drum head. Then, when you go to paint in the future, the fibers will have room to swell, and the paper won’t buckle. This is the most reliable way to guard against buckling on thinner paper. For watercolorists who paint in a very illustrative manner this is often their preferred solution.

Stretching does take some practice. You cannot use regular masking tape when stretching because it won’t adhere to wet paper. You have to use gum tape instead (which is also non-acidic, and better for watercolor paper in that regard). Gum tape contains a water-activated glue that will stick to wet paper. But, if that glue gets too wet it washes off, and the paper won’t stick. This can be a problem when you first apply the paper – if the paper is too wet, the gum tape won’t stick and the paper will shrink as it dries. And it can be a problem if you use very wet applications while painting – the water can reactivate the gum tape, causing it to loosen. If you stretch paper with gum tape, expect failures on your first few attempts. Those failures won’t ruin anything – the paper will still be perfectly usable, but it won’t be as resistant to buckling. Some artists combat this by using staples, either on their own or in addition to the gum tape. This solution works well, it all but guarantees the paper will stretch correctly, but it damages the board you are painting on. This is only a concern if you plan on using that board for years and years.

Thicker paper

The easiest way to prevent buckling is to use thick paper. If you use thicker paper (300lb / 640 gsm or greater) it won’t buckle, even with a large application of water. This is the easiest solution, but its also the most expensive solution by far.

Texture

Watercolor also comes in a variety of textures. As I mentioned at the beginning, paper is made by creating a pulp of plant fibers, then spreading them thin and drying them out. The thing you spread the paper out on is called a linter. Linters are usually made from flat steel plates, fine mesh, or dense felt. The texture of paper comes from partially from the surface of the linter, and partially from the method used to dry it.

Hot Press

If you use heat and a smooth linter to dry the paper, you will literally iron it flat. Paper produced this way is known as Hot Press – it was dried by pressing it with a hot thing. Hot Press paper has little to no texture to it – the surface is reminiscent of printer paper. This is great for illustrative painting like botanical, architectural, or biological paintings, but it takes some getting used to. Because the fibers have been ironed flat, they are more resistant to absorbing water. This can result in streaky washes unless the surface is properly dampened before you paint. This paper is also usually more receptive to lifting pigment. Because the fibers are ironed flat, there are fewer nooks and crannies for pigment to fall into. When you rewet a previously painted spot, you reactivate the paint, and can actually pull it up and remove it from the paper. This is used intentionally in many cases, to erase mistakes, or create effects, but can also be a problem if you want to glaze layers on top of each other and aren’t careful with water control.

Cold Press (Not)

You don’t have to dry paper with a hot iron, you can also just let the water evaporate off of it, or you can spin in very fast. In either case, you will first press the pulp onto the linter. Guess what it’s called if you press it into a linter with something cold. Yep. Cold press paper is also known as “Not,” because it was not hot pressed. Cold pressed paper gets a distinct texture, also known as “tooth,” from the linter it is dried on, and the mere fact that heat was not used. Because heat wasn’t used to dry the paper, the fibers won’t dry as quickly, or as uniformly. This causes tiny bumps and valley in the final paper.

Those bumps and valleys are incredibly useful for a watercolorist. We can lay the pigment down into the valleys, and leave the peaks untouched. In this case you’ll see prominent white highlights among the pigment. This is often used to give the impression of light reflecting off of water, or other surfaces. But those bumps and valleys also cast tiny little shadows onto the paper. You don’t really notice these shadows when looking at a painting, but they have the effect of masking imperfections in a wash. It is about a million times easier to achieve flat washes and smooth gradients on cold press paper than on hot press. Cold press is the most popular surface for non-illustrative watercolor painting.

Rough

Rough textured paper is just that – rough. The linter used to dry rough paper is usually more textured than the linter used to dry cold press paper, and less pressure is applied. These two factors result in paper with higher peaks and lower valleys – a more aggressive tooth. This rough surface is prized by watercolorists who prefer a loose style. It is much easier to achieve that water-glisten effect where you leave the peaks unpainted, simply because the valleys are deeper. Personally, this is my preferred texture.

Size & Format

When you go to purchase watercolor paper, you’ll see a dizzying array of products. The most common formats are notebooks, pads, blocks, sheets, and rolls.

Notebooks

Notebooks are great for practice and studies because they keep all your paintings organized into one place. It is easier to store a notebook than a bunch of loose paintings, and they make a chronological record of your progress. When you are first learning how to paint, you can often see a dramatic improvement from the first page of a notebook to the last page. Filling a notebook is also incredibly rewarding for some reason unbeknownst to me. I don’t know why, but when I put a painting or a drawing on the last page of a notebook, I feel like I have accomplished something, even if it’s full of garbage ugly sketches.

A word of warning when buying notebooks. Watercolor paper is expensive, and so are notebooks made of watercolor paper. If the notebook is very inexpensive, take a close look to be sure the paper isn’t wood pulp paper. You also might want to get a notebook with lay-flat binding. These notebooks are more complicated to build, and hence more expensive, but they won’t have that huge crease in the middle of the book that can make it difficult to paint or draw on.

Pads

Pads are more common than notebooks. These are precut pieces of paper glued together on one side. The glue used to adhere these pages is only applied to the edge of the paper, so it keeps the papers all together, but it’s easy to remove a sheet when you want to. Some people use pads like a notebook, never removing sheets from the others. Some people take the paper off every time they paint so they can stretch it or just paint flat on a flat surface. If you choose to paint on a pad without removing the paper, you should be careful not to accidentally paint the page beneath. It is easy for water color to wick around the edge of a piece of paper and stain the back of the page you are working on. That ruins the back side if you wanted to use it for practice, but in a notebook it also ruins the front of the next page. For this reason, when painting in a notebook, it’s a good idea to not paint all the way to the edge of the paper.

Blocks

A block of watercolor is just a pad, but instead of gluing one edge, the manufacturer glues all four edges together. A lot of beginning plein air painters like pads because they provide a ready-made hard surface to paint on. Because many pages are glued together, and because all sides are affixed, the paper in a pad is also much less prone to buckling. Pads have the added benefit of protecting the paper beneath the one you are working on. Because all sides of the paper are glued together, the water won’t wick around to the back side of your paper. This preserved the back of the paper if you want to use it for pracitice, and protects the front of the next sheet of paper.

When you have finished painting on a block, you need to remove that piece of paper in order to access the next sheet. I have actually seen people who didn’t know that a watercolor block contained multiple sheets of paper, they thought it was just one piece of paper glued onto a tall surface. They were so happy when I showed them how to remove the top sheet – they suddenly “found” $50 worth of paper! To free the top sheet, find the gap in the glue. It’s usually about an inch wide and often at the bottom of the page. Insert a palette knife (or a credit card, anything thin and clean) between the two pages, and run it along the edges of the paper, breaking the glue at that joint. This will free the top sheet of paper from the block, and expose the next sheet ready for a new painting.

Sheets

Unbound paper is referred to as sheets. When you buy sheets of paper, they come just like printer paper, a whole bunch of loose pieces of paper. You can buy sheets of almost any size and in whatever quantity you want. The only downside to buying sheets of paper is carrying them around, or finding a place to store them until you’re ready to paint. This is the most economical way to buy watercolor since you aren’t paying for the binding in addition to the paper. This is what most watercolor artists buy.

You can buy sheets of paper that have been precut to the size you want, or you can buy full sheets and cut them up yourself. Most full sheets are 22″ x 30″ though you can buy “Imperial” or “Elephantine” sheets that are slightly larger. For a long time I was afraid of buying full sheets because I thought cutting them would be hard to do. It’s not. All you have to do is fold the sheet in half, and stick a knife in the fold. Pull the knife as you work down the fold and you now have two pieces of paper (22 x 15, or 11 x 30 depending on if you folded hamburger or hot dog). Cut those in half and you now have four pieces of paper at 11 x 15 (my preferred size for most paintings). You can even cut these down further to make cards if you like.

The benefit of buying full sheets is cost. If you buy full sheets in bulk, you’ll often get paper at the best price. Cutting it into smaller pieces isn’t hard at all, so this is what I choose to do. The only downside is storing the full sheets until I’m ready to cut them up. Fortunately for me, the crawl space in my basement is dry, so I just keep the sheets in their factory plastic in the crawl space, and take a pack whenever I’m ready for more paper. They usually come 5 sheets to a pack, and the factory plastic does a good job of protecting them from any ambient humidity. I’ve had sheets kept like this for four years or more, and they are perfectly fine.

Rolls

You can also buy rolls of watercolor paper. This is usually the cheapest option since the manufacturer has the least amount of work to do. I find rolls a bit intimidating because I don’t have a great place to store them. These are often a pretty big investment, and I’m nervous about having $500 worth of paper just standing in a corner somewhere. I’d rather buy a bunch of full sheets, and just keep them in the factory plastic until I’m ready. Rolls usually aren’t a whole lot cheaper than sheets on a price/inch basis, so I just stay with sheets. Maybe if I ever have a truly dedicated space to painting I’ll change my mind, but for now I just buy paper in full sheets.

Summary

Whew! That was a lot.

Paper. It’s just paper right? How can I have said so much about paper? The truth is, when it comes to watercolor, paper is king. It’s expensive, you use a ton of it, and it has an enormous impact on the final product. For those reasons, I really recommend knowing as much as you can about the paper you buy. Many people learning watercolor start with cheap wood pulp paper, and get frustrated with the results. They follow an online tutorial, and follow the instructions to a t, but get different results. Some people get so frustrated by this that they just give up. The think they can’t master the simplest skill, when in reality it had nothing to do with them, and everything to do with the paper they were painting on.

I don’t recommend spending a ton of money on things. I don’t think buying the expensive pencil or the tajmyr male sable size 20 mop brush is going to magically make your art better. For most supplies, you can get excellent results with subpar equipment. That’s simply not the case when it comes to watercolor paper. I know it’s expensive, I know it’s an investment – so hopefully I’ve given you enough information to help you make the right decision.

And even though this was a super long article – there’s still a ton more to learn if you really want to. Believe it or not, I left a lot out. If you want more information, take a look at the links below. As always, Bruce MacEvoy has a metric shit tonne of great information about paper, so I recommend checking out handprint.com if you really want to know more.

Learn More

Here are some links to other sources of information about watercolor paper. If you know of more good resources, please let me know in the comments.

• Jackson’s Art
• Solving Watercolour
• Handprint.com
• A paper describing the different kinds of cellulose