Depending on how much the paint is diluted (with water) or modified with acrylic mediums such as acrylic gels, media, or pastes, the finished acrylic painting can resemble a watercolor or an oil painting, or have its own unique characteristics not attainable with other media.
The beauty of the acrylic paint along with acrylic mediums when using palette knifes is that you can create some interesting textures that can give a unique look to your overall painting. I love making different textures using the palette knife in various ways that gives a different characteristic to my work.
Many artist who use acrylics thin their paint with water and used as washes in the manner of watercolor paints, but the washes are not re-hydratable once dry. For this reason, acrylics do not lend themselves to color lifting techniques as do gum arabic based watercolor paints. However, if artist uses acrylics for palette knife it would not be as wise to water the paint down. You will not be able to manage the paint as you would a brush if the paint consists of a large amount of water.
There are also acrylic paints with gloss or matte finishes that are available, although a satin (semi-matte) sheen is most common; some brands exhibit a range of finish (e.g., heavy-body paints from Golden, Liquitex, Winsor & Newton and Daler-Rowney). Politec acrylics are fully matte. I personally use paints with a gloss and add a glossy varnish such as Golden Gloss Varnish once the paint is dry. Though the chemicals are toxic and have to be applied outdoors, however; the results gloss varnish are incomparable to some of the other brands.
When dry, acrylic paint is generally non-removable from a solid surface. Water or mild solvents do not re-solubilize it, although isopropyl alcohol can lift some fresh paint films off. Toluene and acetone can remove paint films, but they do not lift paint stains very well and are not selective. The use of a solvent to remove paint will result in removal of all of the paint layers, acrylic gesso, etc.
Only a proper, artist-grade acrylic gesso should be used to prime canvas in preparation for painting with acrylic. (However, acrylic paint can be applied to raw canvas if so desired without any negative effect or chemical reaction as would be the case with oils)) It is important to avoid adding non-stable or non-archival elements to the gesso upon application. However, the viscosity of acrylic can successfully be reduced by using suitable extenders that maintain the integrity of the paint film. There are retarders to slow drying and extend work-ability time and flow releases to increase color-blending ability.
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