AskMaurice.org - Painting on Paper

Paper is made by soaking bark, cloth, or other plant fibers and forming it into sheets using a mold covered by a flat frame called a deckle. Shaken to spread the fibers evenly and drained of its excess water, the wet mat of fibers remaining in the newly formed sheet is dried against blankets & may be hot pressed, cold pressed, or air dried.

Cotton rag 100% paper has become the standard of artist's choice papers due to the paper's tear strength and (when properly sized) it's ability to take the abuse of water color and ink without feathering and bleed through. Cotton when processed yields the tissue alpha cellulose required for the production of permanent papers because their length and crystalline structure make them the strongest. Cotton paper has two sources: linter and rag. Cotton linter has shorter fibers left after the ginning process, which are not used in thread spinning fabric and textile manufacturing. The fibers used for threads are longer and tougher than cotton linter. Cotton rag comes from the part of the cotton plant that is used for making fabrics and textiles. Rag content, is a term taken from the cotton clothes and rags that were shredded for fiber to be used for paper and identifies the percentage of cotton fiber contained in relation to the total contents of the pulp.

Lignin an organic substance, which is removed during manufacturing, is a binder for cellulose fibers in wood and certain plants and it is not desirable in the production of permanent papers. It is has been known to contribute to chemical reactions with light and heat to produce acids, causing deterioration or self decomposition of paper. The measure between acidity and alkalinity known as the pH scale runs from 0 to 14. Seven is pH neutral: below 7 indicates acidity, while pH above 7 indicates alkalinity. Paper without acid in the pulp that has a pH higher than 7.0 pH is the only truly acid free paper. By adding an alkaline substance or "buffer" (usually calcium carbonate or magnesium carbonate) to the pulp to boost the alkalinity, it adds protection against any acid in the paper or what the paper can absorb from environmental conditions. Buffered papers generally have a pH between 8.5 and 9.5. Internal sizing, sizing which is added to the paper pulp, must also be neutral or alkaline. This starch, gelatin rosin, or synthetic substance is added to the paper pulp to provide strength and control of water resistance or absorbency.

Archival papers are monitored not to exceed specified amounts of metallic content. The water introduced to the pulp must be "softened" to remove these contaminates which cause discoloration over time. Iron should not exceed 30 parts per million and copper should not exceed 1 part per million. The paper is also colored in the pulp to assure fade resistance. Some mills use chemicals to obtain a bright white. Only a natural bleached pulp free from "Optical Brighteners" will maintain a stable white color. When a paper sheet is watermarked it identifies when and where it was made. It will show a code that is documented and dated with a translucent design or name made visible when a sheet is held to the light.

Understanding paper

It is important to understand the various classifications for the types of paper available. The choice of papers is quite large and includes various textures and weights. Top quality rag papers are available in the following brands: Arches , Canson , Fabriano , Winsor & Newton , Saunders Waterford , Strathmore , St. Armand , Lanaquarelle , and Whatman. Most paper is categorized by the materials used, weight of the paper, ply, surface, and size. Many of these higher quality papers have watermarks or stamped manufacture marks on one edge of the sheet. Due to the increased concern for the use of archive materials and certifications it is now advantageous for the artist to allow these markings to remain on their painting to validate appraised value.

Ply -Equals a single layer of paper. This term is used in reference to most illustration boards where several sheets of paper are laminated together to form a board.
Weight - Determining the weight of the paper you're about to use is important to understand since it is often referred to in different terms. Let's say you were to purchase a few sheets of 180lb paper and wind up confused because, you just found a few sheets of 140lb that looks almost twice as heavy. Chances are that you had not been informed as to whether the weight was calculated by SQUARE REAM or by SQUARE METER. Below shows briefly how weights differ.

lbs./ream        grs/m2
90                   180
140                   280
300                   640

Many paper manufacturers and retailers can provide you with a reference chart explaining the weights of the papers they have available. Take some time to study them to your advantage.

Surface

Hot Pressed - By pressing a finished sheet through hot cylinders this surface is made smooth. This surface favored for highly detailed work. Great texture for graphite, ink, pastels, etc.

Cold Pressed - Favored for watercolor painting this slight texture is acquired by pressing the sheet between cold cylinders.

Rough - When the wet sheets of paper are placed against textured blankets or allowed to just air dry it creates this heavily textured paper surface. Often used for painting landscapes, were clean sharp edges are difficult to create with this rough-textured paper.

Deckle - The jagged edge caused by the run-off of wet pulp or tearing off at the edges of the sheets when wet.

Preparation

Paper can be used effectively with any medium but each medium requires a different form of preparation. Most painting mediums perform best with an application of external sizing. Since "internal sizing" has no effect on paper porosity, it will not limit the amount of penetration of liquids and pigment. Naturally hydrophilic cellulose paper loves water and will permit ink or water based pigment to soak into paper spreading quickly with random bleeding or feathering causing the artist to lose control of the work (unless done intentionally).

Watercolor - Previous to starting to work you will need to attach or stretch the paper to a stretcher board. When using wood you the surface should be finished with a water repellent coating such as Urethane to prevent wicking of any chemicals from the wood into the back of the paper. There are a few types of stretcher boards on the market such as "Bromley Paper Stretcher" or the ZIPP CLAMP specifically for this purpose however you can make your own. I personally prefer Plexiglas with my own clamp bars for this purpose. Some artists prefer stretching by applying water soaked paper to a board, brushing out the air bubbles and tacking or stapling the wet paper to a board and then allowing the drying process pull the paper tight. It is important to secure the wet paper tightly to the board since watercolor paper pulls enough to pull the staples out when drying. It can take up to 48 hours for the paper to dry completely. As the paper dries the paper fibers contract providing you with a sheet of paper that will remain somewhat flat during the painting process. In a different process some artists soak their paper in water and then do an entire painting on the stretcher board while the paper is still wet. This is known as the "wet on wet" technique (see watercolor). You can also dodge the stretching process by using either 300lb paper or 100% rag museum board.

Unless you are using the "wet on wet" technique, to improve the surface strength characteristics of the paper and to protect the fibers from breakdown due to oxidation, I recommend applying Neutral pH PVA (poly vinyl acetate) Adhesive diluted with distilled water to at least the area of the paper to be painted. External surface sizing encases the cellulose fibers with a chemical barrier that restricts the penetration of liquids and vapors. You can apply external sizing to paper by brushing, or tub sizing. I personally don't recommend spraying since the additional thinning required limits the amount of size utilized. Use a large soft brush or, lightly soak dry sheets in a wall paper tray of liquid sizing. To avoid waste line up several sheets when using the tub method. Afterwards light pressing with an iron between two cotton cloth sheets while the paper is still damp will smooth the buckling commonly associated with wet paper.

Acrylic and Oils - When painting paper with acrylic or oil paint you should be sure to use at least a 140lb/ream paper. However, as in almost every case 300lb/ream or 100% museum board is better. Apply two to three thin coats of Acrylic Gesso diluted (4) parts gesso and (1) part solution of 50/50% water and acrylic matte medium to the area to be painted. Sanding lightly in between coats with fine grade sandpaper, brush on using crosshatched strokes or in one direction changing direction perpendicular to the previous coat. Another effective method is to use a 4" foam roller similar to the brush. This procedure will provide you with a fine ground for painting.

Pastels - Although many paper manufactures produce paper specifically for caulk and oil pastel use such as Sennelier La Carte Pastel Card, Sanded Pastel Papers and Wallis Sanded Pastel Paper , you can effectively make your own pastel paper to prepare the precise texture or (tooth) that your work requires. This can be achieved by sprinkling Pumice or quartz powder onto a thinned consistency of acrylic gesso or Neutral pH PVA (poly vinyl acetate) Adhesive diluted with distilled water that has been applied to 300lb (hot press) watercolor or 100% rag museum board. Then before the surface dries, lightly sprinkle more grit on the sheet evenly across the sheet and set it with spray fixative. Tap off the excess and apply more grit and fixative as needed. Unless you are using oil pastels, avoid excessive coats of gesso since the build up of latex will create a sight resistance to the pastel pigments. You have now created a textured support needed for dry media such as pastels to hold their color particles in place.