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CHAPTER 1
what is acrylic?
Pigments, such as Ultramarine Blue and Quinacridone Magenta, are the same for all types of paint mediums, but the binders are different. For oil paint the binder is linseed oil, for watercolor it is gum arabic. The binder for acrylic products is technically called a polymer dispersion.
The polymer dispersion is basically a mixture of microscopic spheres of clear plastic suspended, or dispersed, in water. As the water evaporates the plastic spheres move closer together, touch and bond, creating an acrylic paint film. As the acrylic dries, the pigments become trapped in the film. The acrylic binder (polymer dispersion) acts as a glue, attaching the pigment to the canvas or paper. In this form, the acrylic is white when wet but dries to a glasslike clarity.
So what is complicated about that? For most artists, this explanation will take you a long way in your exploration of acrylic painting, but for artists who continually want to push the envelope, there's a cornucopia of materials coupled with a world of technical information to investigate.
The manufacture of a professional-grade acrylic requires highly specialized chemists and curious, determined minds willing to test and reformulate acrylic to achieve the optimum combination of pigment, binder, stability and longevity. To achieve this optimum formulation, professional-grade acrylics include things like biocides, coalescing agents, surfactants and defoamers. In addition to this complicated balance, each individual pigment has its own unique recipe for formulation.
categories of acrylic
Acrylic can be separated into several categories:
Paint
This category includes all the different paint viscosities of acrylic with color pigments. These include heavy body, fluid, Airbrush and OPEN acrylics.
Mediums
Mediums are acrylics without pigments. Gels and pastes are a subset of mediums. Mediums, gels and pastes are all designed to mix with paint.
Fluid Mediums are mediums that are thin and pourable such as Polymer Medium (Gloss), Matte Medium, OPEN Acrylic Medium (Gloss) and Acrylic Glazing Liquid. Mediums are typically used to change or extend your paint and to make glazes.
Gels are basically colorless paints. They are thick and range from transparent, semi-transparent and opaque. They can also be filled with particulate matter. Examples of gels include Heavy Gel (Gloss), Soft Gel (Matte), Clear Granular Gel, Coarse Pumice Gel and Self Leveling Gel.
Pastes contain marble dust, clays or other fillers resulting in a white or clay finish and are usually opaque and used to create texture. Some examples include Fiber Paste, Molding Paste and Coarse Molding Paste.
Additives
Additives have no acrylic binder so there's a limit to how much additives you can mix with paint. There are three additives: Acrylic Flow Release (water tension breaker), retarder and OPEN Thinner (both retarder and OPEN Thinner slow acrylic's drying time).
Gessos
Think of gesso as the bridge between the support and your paint. White gesso and black gesso fall into this category.
Grounds
A ground is a product that provides a desired surface on which to paint. Grounds can provide a surface to apply pastels, watercolor or other products. Examples of grounds include Absorbent Ground, Acrylic Ground for Pastels and Digital Grounds.
Varnishes
Varnishes are designed to be the final protective coating for a painting. They should be removable and add UVL protection. Polymer Varnish, MSA Varnish and Archival Spray Varnish are in this category.
options in paint viscosities
A paint's viscosity simply refers to how thick or thin that paint is. Thin paints are said to have a low viscosity, while thick paints have a high viscosity. Let's look at the options in acrylic paint, beginning with the thinnest, or lowest, viscosity.
... Airbrush colors have a low, ink-like viscosity and dry slowly because they need to move through an airbrush without clogging it. They're magnificent for staining canvas and as watermedia. Next time you want an extremely fine line, use Airbrush colors.
... Fluid acrylics have a thin, pourable viscosity with an equally strong pigment load to heavy body acrylics.
... Matte fluid acrylics have matting agents added to them, creating low-viscosity paints that dry to a flat, gouache-like finish.
... OPEN acrylics have a creamy viscosity for applying thin layers of paint used in traditional blending techniques. OPEN acrylics stay wet for longer periods of time.
... Heavy body acrylics have a high viscosity that's designed to hold a brushstroke and spread like butter with a palette knife.
... Matte acrylics are a version of heavy body acrylics that are designed to dry to a matte finish that will hold a brushstroke.
heavy body acrylics
A substantial viscosity, rich with pigment and free from fillers or matting agents, is the hallmark of heavy body acrylics. The creamy quality of these paints makes them one of the most popular types of acrylics.
fluid acrylics
A gorgeous pour of Pyrrole Red shows off the liquid viscosity of fluid acrylic paint. Fluids are a great solution for artists who want to create a smooth paint surface. If you're always thinning down heavy body acrylics, then fluid acrylics might provide the viscosity you're looking for.
OPEN acrylics
Because OPEN acrylics are created with a unique polymer, they are well suited for blending and can sit on a palette for days without drying. They can be mixed with all types of gels and mediums.
organic and inorganic pigments
There are two chemical classifications of pigments: the technical terms are organic and inorganic. However, it's easier to distinguish these pigments by their nicknames: modern and mineral.
modern (organic) pigments
These pigments are generally translucent and have a high chroma. Modern pigments also have a high tinting strength (think Phthalo Blue) and make very clean, bright glazes.
mineral (inorganic) pigments
Mineral pigments are easy to recognize because they have names that reflect their origins, such as Sienna, Oxide, Umber and Ochre. These pigments have a relatively low chroma, a low tinting strength and are generally opaque.
pigment reality
Knowing the differences between modern and mineral pigments is essential for successful color mixing. Mineral pigments, partly due to their opacity, make mixtures of a lower chroma than mixtures made from the modern family. This isn't color theory, but pigment reality. Acknowledging this will give you control over your color mixing choices.
use professional-grade paints
Professional-grade acrylics are simply not what they used to be. They have higher pigment loads, and, if fillers are used at all, they are used only to produce unique formulations, not to fill up space or reduce the cost. By selecting professional-grade acrylics, you'll get more pigment for your investment, allowing you more ways to manipulate your paint with gels and mediums. The color will mix more easily and will not shift as much as it dries. Lastly, the binder of professional-grade acrylic paints is designed with the goal of making them resistant to chemical changes resulting from reactions with oxygen, water and exposure to ultraviolet light. While it's not known how long acrylic films will retain their physical qualities, current tests suggest they will last hundreds if not thousands of years.
student vs. professional acrylics
Here you can see the difference between student-grade Naphthol Red Light and professional-grade. Notice the transparency of the student-grade paint compared to the professional-grade. In the second row, 1 part red has been mixed with 10 parts Titanium White. When the pigments are mixed with white, the considerable difference in pigment load becomes obvious.
pigment control
Each of these color wheels was made by mixing three primary colors. The mineral pigment color wheel used Cadmium Yellow Medium, Cadmium Red Medium and Cobalt Blue. The modern pigment color wheel used Hansa Yellow Medium, Quinacridone Magenta and Phthalo Blue (Red Shade). Notice the translucency and brightness of the modern colors compared to the opaque, dull mineral mixtures. One is not necessarily better than the other, but knowing their differences will give you more control over your palette.
read the paint label
By federal law, all paint must be labeled with health and safety precautions. Read all the information on the label, though it can be confusing at times. Here's a simple and effective way to approach all art materials. First, consider how these materials can get into your body: inhalation, ingestion and absorption through your skin. Second, these materials are tested, but they are tested for use. "For use" with paints and gels indicates the expected use is that you take the paint out of a jar with a palette knife or brush and directly apply it to a surface. These products are not designed to be face paint, tattoo ink, hand cream or room deodorizer. When a label indicates that it's not toxic, it's assumed you will not eat it or finger paint with it.
safety label
Through the American Society for Testing and Materials (ASTM) art materials are tested and labeled for chronic health hazards. It's essential that you follow the precautions listed on these labels. In other words, reading the label is important.
anatomy of a paint label
... Lightfastness rating indicates if a pigment will fade or darken when exposed to long periods of ultraviolet light. A lightfastness rating of I (excellent) or II (very good) is considered suitable for archival paints.
... Paint swatch is a hand-painted swatch of the Quinacridone Magenta over black lines, indicating the level of transparency.
... Pigment identification number refers to the color index number. P is for pigment and R stands for red. The 122 is the color index number, which is useful if you are looking at different manufacturers and want the same pigment.
... Product codes are used by all manufacturers to describe the color and size of a product.
... Series code refers to the retail price for each series.
tools and tips
A plethora of implements can be used to move acrylic around on your painting surface.
... Palette knives. These are great for mixing and applying paint. You can select either stainless steel or plastic. (Dried acrylic can be peeled off a plastic knife.) Even big cooking spatulas can be used as palette knives for applying paint to large areas.
... Brushes. Select a variety of round, flat and filbert brushes in different sizes and handle lengths. Generally, use smaller brushes for smaller paintings and detailed work, and larger brushes for larger paintings and for laying in large areas. Synthetic bristles are handy for their range of stiffness and ability to sit in water for long periods of time. Wide, flat house-painting brushes are great for priming your surface with gesso. Faux-finishing brushes are handy for blending and special effects. Natural-hair brushes such as sable and mongoose are good for very smooth, oil-like blending, so keep a few on hand.
... Sponges. Flat sponge brushes and sponge rollers can be used to create interesting textural effects.
... Additional tools. Metal combs can be used to scrape in interesting textural surfaces. Window scrapers, paint scrapers and putty knives are handy for excavating layers or cleaning your palette. It's also good to have a spray bottle filled with water for misting your surface and another spray bottle filled with isopropyl alcohol, which will dissolve acrylic for unique textural effects. Have a selection of tapes on hand for masking off areas you don't want to paint, or for creating straight lines. Color shapers, available in a range of widths from very fine points to 5" (13cm) can be used to carve into the wet acrylic surface. Finally, always have a flathead screwdriver on hand for opening gallon containers.
care of brushes
With acrylics, synthetic brushes or synthetic-blend brushes are best for everyday use and can be washed with soap or brush cleaners. Pay special attention to your expensive natural-hair brushes. Keep them separate from your regular brushes. Condition them with an inexpensive hair conditioner by rubbing a small amount into the filaments after use, then rub in a bit of conditioner for storage. Soak brushes that have become rock-hard in specially formulated brush cleaners.
drying time
The standard refrain about acrylics is that they dry too fast. For some painters, though, too fast is not fast enough. If you want to speed up the drying time, let fans blow over the painting's surface. Or let the painting dry in a hot room, or under a heat lamp, or place a heating pad under the substrate. If you want a longer open time (open time is how long the paint is workable), consider using OPEN acrylics (for thinner layers) or working in cooler temperatures. You could also use thicker applications of paint and gels or mix Acrylic Glazing Liquid or retarder into your paint.
substrates
When working with acrylics, almost any surface can act as a substrate, including canvas, paper, wood, ceramic, bisque ware, Masonite, fiberglass, Plexiglas, and--with proper priming--metals and glass. Wax, surfaces with oil paint, unprimed metal, and water-sensitive surfaces are the few substrates that are not recommended for use with acrylic.
preparing the substrate
As with most paints, the most critical factor in obtaining a good adhesion between the paint and the substrate is to properly prepare the substrate. A quick rule of thumb is to apply two thin coats of GAC 100 allowing each layer to dry thoroughly before applying the next. Then apply two to three coats of gesso, also letting each layer dry before applying the next.
preventing support induced discoloration (sid)
During acrylic's drying time, water moves back and forth between the paint and the painting support and actually pulls the "dirt" of the support into the paint layer. To prevent this, the best practice for acrylic painters is to prime any painting support with two coats of GAC 100 before applying gesso. Common art supports, such as cotton and linen canvas, Masonite and some papers, contain water-extractable materials that can discolor transparent glazes or thick gel applications.
environmental studio practices
Always dispose of acrylic paint in a dry form; don't wash acrylic down the drain. Wipe your tools with paper towels to take off as much paint as possible before washing.
Wash brushes in a container, then pour the water you used to clean the brushes into a gallon bucket and let the water evaporate. Peel the layer of pigment and dried acrylic from the bucket's sides and bottom and throw the chips away.
watermedia effects
THIS CHAPTER IS ALL ABOUT WATER, washes, stains, bleeds and blooms. It's about taking time-honored watercolor techniques and "blowing them out of the water." Using acrylic gels and grounds, you can create a variety of surfaces with varying degrees of absorbency that will allow you to put acrylic on numerous substrates. We're not talking just paper or canvas anymore--now you can use wood, ceramics, Plexiglas and metals. Almost any surface can be made to accept acrylic, giving us an embarrassing number of porous surfaces to paint on.
maximizing washes
fluid acrylics
Acrylics must be thinned with water to create a wash consistency, and the very best acrylics to dilute are fluid acrylics. These are thinner in viscosity than heavy body acrylics, yet they have the same amount of pigment per ounce, requiring significantly less water to achieve rich, vibrant stains.
Acrylics are great for multilayered washes. Since they aren't resoluble (like watercolor), they will not lift and remix with the new wash and will hold a tight, clean edge.
staining and granulating pigments
Watercolorists who are familiar with pigments that stain and granulate will find that acrylics act in much the same way. Inorganic or "earth" pigments are heavier, and when suspended in water on a highly absorbent surface, will fl oat out into the larger crevices of the surface. Organic pigments will stain into any and all microscopic pockets.
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Excerpted from "Rethinking Acrylic"
by .
Copyright © 2008 Patti Brady.
Excerpted by permission of F+W Media, Inc..
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