Acrylic paint is a popular medium for all levels of painters, ranging from the absolute beginner to the well-established professional. Part of what makes it so user-friendly is that it is a water-soluble paint made from a plastic polymer that can be painted on any surface that isn't too greasy or glossy and can be used in a variety of ways - thinly like watercolor, thickly like oil, or mixed with other media.
Paper provides an excellent flexible surface, also called support, to paint on with acrylics. It is portable, light-weight, and relatively inexpensive compared to canvas, linen, and other prepared art boards. Paper is particularly good for small to medium-sized paintings or studies and can also be used for larger paintings when a suitable heavyweight paper is chosen, or when used as part of a series, such as in a triptych. When prepared right, it can accept a wide range of acrylic and mixed media uses.
Paper should be durable to resist tearing from erasure, heavy paint application, sanding, scrubbing, scraping, and other techniques. Paper made from cotton or linen pulp tends to be a stronger and more durable paper than that made from wood, which may contain acids. You might see it labeled "100% cotton" or "100% linen" or "pure cotton rag."
Paper should be heavyweight. You want to choose a heavier weight paper that will not buckle when you use a lot of water or medium with your paint (unless you are doing quick studies and don't care about buckling). We recommend using not less than 300 gsm (140 lb) to avoid buckling. Heavier weights are even sturdier and can be mounted on a board or canvas more easily.
Paper should be acid-free for longevity. The acidity of the paper is an indicator of its archival quality, or how long it will last. You want a pH neutral paper, which means that the cellulose pulp should be pH neutral and any primer used should be free of any chemicals that might cause acidity. High-quality papers will indicate that they are acid-free.
Paper should not discolor with age. Papers that contain acidic components are prone to yellowing, discoloration, and become brittle with age. These papers are less expensive papers such as regular copy paper, brown wrapping paper, newsprint paper, etc.
Paper should not be glossy, oily, or too smooth. Paper comes in different textures. It needs to have enough tooth, or surface texture, to absorb the pigment. There are different roughnesses of paper available in watercolor papers - cold pressed watercolor paper is generally rougher and has more tooth while hot pressed paper is smoother. Smooth paper allows your brush to glide easily along the surface, and is good for fine detailed work, but may not absorb the paint as well. Rougher, more textured paper is good for loose, expressive work and for "happy accidents" of textural detail. There are also papers that mimic the textures of canvas, such as Canson Foundation Canva-Paper Pads and Winsor & Newton Galeria Acrylic Colour Paper Pad.
As long as you've chosen a high quality, acid-free paper, you can paint acrylic directly onto the surface of the paper and be assured that your painting will be of archival quality. When painting with acrylic you do not need to prime the paper first since the paint, a plastic polymer, will not damage the paper. However, the paper will still absorb some of the moisture and pigment from the initial layers of paint. (This is true even though the most high-quality paper is treated with surface sizing for water resistance) So if you want the paint to glide on more smoothly at first we recommend applying at least two coats of acrylic gesso before painting.
If you are using a paper that is not acid-free you should gesso both sides of the paper to seal it before beginning to paint. If you prefer a clear sealer you can also use a matte gel or medium to prime both sides.
You can paint on many different surfaces with acrylic paint. While good quality acid-free papers are the best for archival purposes, don't be afraid to try out other papers as well. You never know what you might discover and enjoy.