Acrylic paints were initially developed as industrial paints that were first used by artists after WW2. The first acrylic paints were called Magna paints and were soluble in paint thinner. Shortly after, water-based acrylics were developed as house paints (latex). Artist quality acrylic paints are composed of pigment suspended in pure acrylic emulsion. When wet, acrylic paints are soluble in water, but dry to an insoluble hard plastic. Acrylics are extremely versatile and can be applied with a wide range of textural effects. Because of their consistent drying time and flexibility, there are few rules in how they are applied. Thin layers can be applied on thick and visa versa. To create bled or poured effects, polymers can be directly applied to raw, unprimed canvas. Oil paints cannot be used in this way because acids naturally present in the oil will eventually cause canvas to deteriorate. Because acrylics are fast drying, thickly painted works can be completed quickly. If necessary, an acrylic retarder can be mixed with acrylic paints to help slow their drying. Acrylics are well suited for building transparencies and/or flat color, rather than for painting that requires delicate control and blending. Acrylics will peel from glass or other non-porous surfaces but bind well to cloth, wood, and unglazed ceramic.
Polymer medium - is the binder of acrylic paints that can be mixed with polymer colors to create smoother consistencies and glazes. A polymer medium (matte or gloss) has a milky color when wet, but dries completely transparent if used properly. Gloss medium can be used as a final varnish over acrylic painting. Matte medium works the same way, but has a duller finish. Polymer medium may dry cloudy when brushed continuously while drying or when diluted with too much water (not to exceed 25% water to medium).
Iridescent medium is available for "metallic" color mixtures. An iridescent color can be made by mixing a transparent acrylic color with this medium.
Polymer mediums can also be used as adhesives and work well when incorporated in mixed-media and other techniques. Polymer mediums are ideal for use in collage, or attaching tissue paper to the surfaces of canvas or board. Oil paint, oil glazes, and oil sticks can be applied over any acrylic surface. Chalk pastels (pigment plus clay) can also be used in combination with acrylic or oil paints.
Acrylic Polymer Gesso - is used as a primer (or ground) for both acrylic and oil. Acrylic gesso is usually opaque white, however black gesso is available for opaque black grounds. Color gesso can also be purchased for artists interested in using color grounds.
Taping - Sharp edges can be made in acrylics without the paint bleeding or crawling under masking tape. Artists seal the masking tape edge or edges with polymer medium, allowing it to dry, then painting in the masked-off areas.
In addition to gloss, matte, and gel medium, acrylic polymer gesso can be mixed with aggregate materials such as sand, marble dust, or cement to produce textural or sculptural effects.
Gel medium - Similar to polymer medium, polymer gel can be mixed with varying amounts of acrylic colors to create opaque or transparent impasto effects. Used by itself, gel medium dries transparent. It is well-suited for mixed media techniques and can be used as an adhesive or applied on top of collage, modeling paste, cloth, wood, unglazed ceramic, sanded metal, or any acrylic surface. Gel medium is now available in matte, gloss and opaque finishes. Golden makes a variety of gels that also include heavy, regular, and soft gels (see below).
Modeling Paste - Modeling paste is a blend of acrylic polymer and marble dust. Textural effects can be created with modeling paste directly on gessoed surfaces. However, modeling paste may crack on flexible surfaces (such as canvas) unless gel medium is added. Modeling paste is thick and opaque and dries white, so it should be used for textures on which glazes or paints are applied on top. It creates a stucco-like surface.
Golden Acrylic mediums and gels - One of the most innovative art supply companies specializing in acrylics is Golden Artist Colors. Golden continues to develop unique acrylic mediums, gels, and pastes for use by artists. Some of those gels and pastes include: