Poster boards are used for a myriad of purposes. Artists use poster boards as backing for their paintings and collages. Businesses use them to make semi-durable signs for advertisements or to mark directions. Teachers use poster boards to display student projects. Poster boards come in varying thicknesses and are comprised of different materials. The type of poster board you need depends on the application for which it will be used.
Foam Core Board
Foam core is made of a polystyrene core and a white clay-coated or brown paper facing. The first white foam core board was made for the graphic arts industry and called Fome-Cor. Today there are numerous competitors making the board. The way that polystyrene bubbles are formed during the manufacturing process allows the edges of the board to stay sealed or crimped when die cut. The downside is that accidental impressions or dents can permanently damage the board.
The foam part of foam core is not affected by moisture, but the facing is. This means outdoor use and wet mounts can be problematic. Foam core can be used for oil and acrylic painting, but the foam is sensitive to solvents, so use of lacquers and shellacs is not advisable. Foam core is easily cut with a sharp razor blade, but a dull or nicked blade will tear instead of cut. Foam core is commonly used for vacuum and dry mounts.
Gatorfoam is a board with a foam centre made of Dow styrofoam polystyrene using a Luxcell veneer. Styrofoam is a much harder and more durable form of polystyrene foam, but does not age any better. The hardness of Gatorfoam makes it difficult to cut without a table saw. A major advantage of Gatorfoam is its thickness. Gatorfoam can be as thin as 3/16ths of an inch, up to 1 inch.
Gatorfoam is made with two different surfaces, one in white, and one in brown. The brown paper surface is best for painting and mounting. There are two grades: Gatorfoam I is standard, and Gatorfoam II is less expensive and is made with an expanded polystyrene centre. Gatorfoam II is mainly used in building models and as a substitute for plywood.
Artcore, manufactured by the Amoco Company, is a poster board that is not paper-surfaced like other boards, but is entirely plastic. It is made out of polystyrene foam and is covered with a sheet of white styrene. Being made entirely of plastic, it is fully waterproof. The surface sheet of styrene is also treated with an ultraviolet inhibitor to keep it from degrading in sunlight or fluorescent light. The downside to the surface being non-absorbent is that it makes mounting difficult. Artcore is more practical for making signs, displays and models.
Paperboard is a thin composite, generally 10 mils or thicker. Some paperboard is used for making corrugated fiberboard as well. Cardboard, as it is also called, is a more generic term that refers to any heavy pulp-based board, like card stock and corrugated fiberboard. Another common use for paperboard is for art and craft projects for collages and other projects. Paperboard is the most common form of posterboard.