✿    How papers are made

Paper manufacturers use the fibrous plant material cellulose, which plants use to build the cell walls in stems and leaves.  For European and American papers, cellulose is extracted from cotton, flax (linen) or wood pulp, for traditional Asian papers from jute, kozo, salago or mitsumata. A sheet of paper is basically a thin mat of tangled cellulose fibers. The grade or quality of cellulose is determined by how much of the plant material dissolves in different chemical solutions. Based on this characteristic we know alpha (portion of plant material that does not dissolve in a moderate solution of sodium hydroxide at room temperature) and beta (the dissolved portion that precipitate when an acid is added to the solution) cellulose. Alpha cellulose is the most stable and permanent part of extracted plant material.

Cotton cellulose fibers are called cotton rag, these fibers are flexible and strong, and because they are naturally long, they produce papers that resist tearing. They are almost 100% alpha cellulose, naturally white and already separated, which means little or no bleaching or chemical treatments are necessary. Linen cellulose fibers (from flax) are longer and stronger than cotton, which makes linen papers harder and more translucent. By far the most common source of cellulose in machine-made papers is wood pulp. Cellulose is extracted from wood pulp using either mechanical or chemical methods, resulting in a coarse, brownish paper commonly used in wrapping papers, packaging, newsprint and paperboard. Mechanical methods can leave a considerable residue of lignin, a kind of glue that binds together the cellulose fibers of a living plant. Lignin repels water, causes clumping in the paper pulp during manufacture and becomes acidic and turns a yellow or brown color with age, so it is necessary to remove it completely in quality paper production (look for acid-free papers).

CONCLUSION & RECOMMENDATION: Cotton cellulose is up to 10 times stronger than wood cellulose and naturally lignin free and acid free. Some residual lignin and chemicals remain in chemically extracted wood cellulose, which cause embrittlement and acidification over time. For this reason, wood pulp papers should generally be avoided for archival or museum quality artwork. Papers made from 100% cotton, 100% linen or pure cotton/linen rag are all suitable for artistic use.

✐   2. Brushes

In the past, artists used to make their own materials. Nowadays, painters rely on commercial brand reputation, recommendations from other artists/art books or simply stick to what they know. Good advice does not always last, don't be surprised if you realize one day that the product you always used is somehow different (manufacturers can change their products or simply stop making a specific pigment).

Commercial watercolor paints can be purchased in two most common forms - pans (dry cake in small plastic cans) and tubes (a thick liquid or paste packaged in metal cubes). There's much more to the forms of packaging than difference in price. Dry pan colors are quick to set up and paint with, also very easy to clean up. If well protected, they will store indefinitely. There is no wasted color, they are compact and easy to transport, but also harder to make mixes with and relatively expensive for the amount of pigment they contain. Tubes, on the other hand, are efficient for mixing up large quantities of paint. They are ready for mixing straight from the tube and dissolve quickly in water. However, it's hard to judge just how much paint you need for your next painting, and whatever amount you don't use ends up wasted (re-wetting a dry tube paint on your palette is not recommended). Also, once a tube paint gets contaminated with other colors, it's hard to retrieve. Finally, metal tubes are not ideal packaging solution due to numerous reasons (pigment and its vehicle separate when paint isn't used for some time, the cap sticks if it's gummed up with paint, paint can dry out). Some artists claim that using tube watercolor paints leads to more vibrant results but the difference may simply be due to the fact that it's easier to achieve a high concentration of paint and water (some use paint straight from the tube) - the pigments are identical in either form. Another ugly myth is that pans are for children and students while tubes for "real" artists, in history many exceptional painters preferred pans even in a studio.

With all that being said, I still suggest - if you are an occasional painter - to get pans over tubes, due to practical reasons. 

The newest packaging idea are liquid watercolors - pigment and vehicle prediluted in distilled water. This is a category with significant differences among products. The most popular brand is Dr. Ph. Martin's. These radiant watercolors are not true watercolors (pigment suspensions) but moderately diluted, synchromatic transparent aniline dyes. Many of these colors are exceptionally brilliant but equally fugitive - they stain the paper immediately and cannot be revised. These colors are efficient enough to use in graphical art applications intended for photographic reproduction or printing, but otherwise they are not suitable to be used in an artwork you expect to last for more than a few months.

✿  Other attributes of watercolor paints

✿ Watercolor pigments > are either natural (found in earth, mineral, clay etc.) or synthetic. Here is a great resource to learn everything about the material attributes of paint. When choosing pigments for your palette, use GUIDE TO WATERCOLOR PIGMENTS.

✿ Lightfastness > this factor indicates whether the color you see in a painting today will last. Once you've chosen and purchased paints, it is recommended to do your own lightfastness test.

✿ Transparency > transparent watercolor allows the light to shine through the watercolor paper and in turn lets the white of the paper reflect back. The colors look clean, crisp and appear to glow. Opaque colors, on the other hand, block the light from coming through to the watercolor paper. Instead, the light bounces off the pigment. This can make the colors appear to look dull, even though some of the opaque's are quite vibrant in color. Information about whether the color you've chosen in transparent, semi-opaque or opaque is usually provided in a catalogue.

✿ Staining > Non-staining watercolor pigments will settle on the paper surface once the water has evaporated. These colors allow you to lift the pigment off the surface and reveal the white of the paper underneath. Staining color, in contrast, immediately absorb into the first few layers of watercolor paper and will leave a stained tint of the color. Again, use the recommended GUIDE TO WATERCOLOR PIGMENTS to see which pigments stain strongly and which don't (pigments stain simply due to a very small particle size). Beginners will be better off using non-staining pigments.

✿ "Artist" versus "Student" paints > Some manufacturers offer two lines of watercolor products - artist (finest) quality and a student line that is typically less expensive and comes in a smaller color selection and tube sizes. The cost difference is usually achieved by using less or a lower grade of pigment and the addition of brighteners and fillers. Since price is a poor judge of quality of a product, "professional" paints made by some manufacturers can be of lower quality than student line of the most reputable brands. It is highly recommended to buy the highest quality product and focus on value for your money (tinting strength, lightfastness, packaging quality and color appearance).