Acrylic paints and varnishes are colorants based on plastic dispersions . They can often be diluted with water and harden to form a waterproof coating. There are also acrylic paints that are based on organic solvents .
In 1934, BASF created the first ready-to-use, aqueous acrylic resin dispersion. Röhm and Haas registered the patent for it in 1930 under the name Plextol . In 1946, the Bocour Artists Colors company in New York City launched their Magna Plastic product line , the production of which was not discontinued until the 1990s. Depending on the degree of polymerization, the solvents were initially toluene or xylene , later it was white spirit (Acryloid to the called F-10 ).
The acrylic resin paints made on the basis of polymerized acrylic acid esters were first produced by artists' paint factories for use in painting at the end of the 1940s in the United States , and from the early 1960s also in Europe . Today they are also used in craft, industry and in the hobby area.
The binding agent in the acrylic paint is initially milky white and only becomes transparent when it dries. Therefore, acrylic paints will darken slightly as they dry. Since the paint can be mixed with water, it is sometimes used instead of watercolor and wall paint .
Acrylic paint can be used as an alternative or complement to oil paint and with most of the painting techniques commonly used here. The drying time of pure acrylic paint is very short, but can be artificially extended with painting materials. The paint can be applied using the impasto technique with brushes or painting knives and dries even in thick layers without cracking. When thinned with water, the acrylic paint can be painted in a transparent manner. With the help of acrylic binders , thin glazes can be applied, similar to watercolor painting . The dried paint is slightly shiny and forms an elastic film on the painting surface. Acrylic paint can be used on any grease-free painting surface (e.g. canvas, wood, metal). When using oil paints at the same time, the acrylic paint can be used as an underpainting. However, solid image carriers such as painting boards are required for very impasto working methods and image design with pastes and gels . For color changes and light effects, modeling paste and other texturing agents such as effect, fiber and metallic gel can be used in acrylic painting. The structure gel or structure paste can be applied to the primed painting surface with a variety of tools such as painting knives, combs or spatulas and then colored.
Tools can be cleaned with water; the paint only becomes insoluble in water when it dries and must then be removed with special solvents. Compared to oil paint, water-based acrylic paint has a very low odor when painting.
Acrylic paints in craft
In the construction and do-it-yourself sector, acrylic paints have largely prevailed against comparable products such as nitro or alkyd resin paints . One advantage is that the harmful solvents used are significantly reduced (7 to 15%) compared to, for example, nitro lacquers (70 to 80%). The initially lower abrasion resistance compared to synthetic resin paints was largely offset by new product developments.
Like other paints, acrylic paints essentially consist of three components:
- Pigments . There are organic, inorganic and effect pigments . In addition to the color , the covering (covering of the substrate) and color (changing other colors) are the most important properties.
- Binders serve to connect the pigment particles to one another and to the substrate. Acrylic binders consist of synthetic resin particles that are in high concentration in the solvent (water). When the water evaporates, the particles combine and form a water-insoluble, elastic layer. The type of binder determines properties such as elasticity, thinnability and adhesion.
- Solvents in which the binders are dissolved. Their evaporation leads to hardening. In contrast to oil paint, it is mostly water here. Due to its evaporation, the paint mass loses its volume slightly.
The smell that acrylic paints give off is due to volatile organic compounds. The Fraunhofer Institute for Process Engineering and Packaging IVV examined the odor-active components of acrylic paints in more detail in 2018. For the analysis, six acrylic paints that are regularly available in the trade were selected for artist use. The smell is mainly due to various benzene derivatives. The main odorous substances identified are styrene , ethylbenzene , isopropylbenzene , sec-butylbenzene and n-propylbenzene . They cause the plastic-like and solvent-like smell of the colors. Polycyclic aromatic hydrocarbons , including naphthalene , indane and tetralin derivatives, and various acrylates also play a decisive role .
The subjective perception of the smell is - depending on the use z. B. with artists - different. In the living area, many people find the smell pleasant, which promotes environmentally friendly use.
Painting and aids
- Ground white ( Gesso ): serves as a primer on all unprocessed painting grounds.
- Thickeners : increase the consistency of the paint and are well suited for an impasto application or for working with a spatula.
- Retarders: extend the drying time of the paint. Good for working with the wet-on-wet technique . Glycerine can also be used as a cheap substitute . Drying accelerators ( siccatives ) are not used with the already quick-drying acrylic paints.
- Modeling pastes: allow after several hours of drying, without significant shrinkage of the volume, a plastic post-processing with abrasive materials or knives.
- Shine dispersions (media): influence the gloss properties in stages from semi-gloss to high-gloss.
- Varnishes : create a lacquer-like protective layer on the surface. The color brilliance can be increased (gloss varnish), retained (neutral varnish) or reduced (matt varnish).
- Perfluorinated surfactants : improve the wetting and surface properties, concentrations from 300 to 500 mg / kg (flow control agent).
- Acrylic binders: enable the production of acrylic paint, the painting of fine glazes and are also suitable as an intermediate varnish.
- Thomas Hoppe: Acrylic painting. The artistic techniques , Ravensburger Buchverlag, Ravensburg 2000, ISBN 3-473-48408-3 , pp. 26–32.
- Fraunhofer IVV: Harmful odorous substances identified in acrylic paints - Fraunhofer IVV , accessed on January 3, 2019
- Patrick Bauer, Andrea Buettner: Characterization of Odorous and Potentially Harmful Substances in Artists' Acrylic Paint. In: Frontiers in Public Health. 6, 2018, doi : 10.3389 / fpubh.2018.00350 .
- Thomas Hoppe: Acrylic painting. The artistic techniques , EA Seemann Verlag, Leipzig 2000, ISBN 3-363-00810-4
- Max Doerner : Painting material and its use in the picture. , Enke Verlag, Stuttgart 1994, ISBN 3-432-81048-2
- Brigitte Waldschmidt: Acrylic workshop. Structural means and their application. English publisher . Wiesbaden 2005, ISBN 978-3-8241-1317-0
- Manfred Hönig: Acrylic painting. Tools and possibilities. English publisher. Wiesbaden 2003, ISBN 978-3-8241-1227-2