Gesso has an absorbent quality that prevents paint from bleeding or seeping when it's used as a primer on canvas, panel, paper, or other substrates.
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Before creating a painting of any kind—whether you're using oils, acrylics or tempera paints—it's important to apply a primer to the surface upon which you're painting. One type of painting surface primer that's been around for centuries and is still used today is gesso. Its purpose is to prevent paint from soaking into the weave of the canvas or any other material.

What Gesso Is Made From

Gesso is a pretty simple material—it was originally made from a mixture of chalk or plaster and glue. In fact, the word "gesso" stems from the Italian word meaning "chalk." Today's gesso is typically a bright white mixture of calcium carbonate and acrylic polymer medium used on canvas, panels, or heavyweight paper, according to Ashley Nordin, education developer at BLICK Art Materials. "The chalk or plaster component of gesso makes it absorbent so that when paint is applied to a surface primed with gesso, the moisture wicks evenly from the paint without any bleeding or seeping of paint binders such as oils into the fibers of the substrate, which can cause a breakdown of the painting in the long term," she says.

When to Use Gesso

While there are other types of primers out there, including latex, if you're painting with acrylic or oil, gesso is the best option. "This is because the calcium carbonate mixture and acrylic polymer medium are designed to be compatible with each other and help to better absorb those materials for an ideal color application," says Nordin. Needless to say, gesso is definitely an artist's studio essential.

Nordin recommends always priming pre-stretched store-bought canvas with a couple layers of gesso prior to starting a painting, even if it has already been primed. "Practicing this step will help to retighten the surface if there are any minor dents in the canvas, as well as refresh and brighten up your background," she says.

Different Types of Gesso

You can often find acrylic gesso in three grades—studio, artist, and professional. The difference among these three grades, according to Nordin, is the amount of concentrated gesso in the formula. "The professional-grade gesso is highly concentrated and should be thinned with water for the best application," she says. "Artist-grade gesso is slightly less concentrated than its professional counterpart, and even less so with the student-grade gesso that is almost ready for use right out of the container."

How to Apply Gesso

Gesso can be sprayed on or applied with a brush onto a substrate such as canvas, panel, or paper, explains Nordin. "It can absorb layers of paint without any bleeding or seeping of the painting medium (i.e., oil stains)," she says. "Gesso allows the surface to accept the paint, so that paint and mediums do not soak into the fibers of the substrate, which can ultimately cause long-term or severe damage to a painting."

To start, Nordin says to combine acrylic gesso with a small amount of water to help the primer glide along the surface. Next, she says to apply two to three coats with a large brush, brushing each layer in the opposite direction of the previous stroke before allowing layers to dry between applications. Once dry, she recommends lightly sanding using a fine grit sandpaper until the surface is smooth.

Gesso Techniques

Since gesso has a stiff formula, it should be thinned down with water or paint thinner for an ideal, smooth application. "Because of this, gesso acts as a modeling paste when it is applied in heavy amounts to a work surface and allowed to dry," Nordin says. Its stiff formula can serve as a great way to create textures for abstract painting, notes Nordin, or to build an under layer of texture for a landscape painting. If you go this route and decide to create a sculptural texture with gesso, she recommends using a palette knife for the best results.

How to Make Gesso at Home

While you can certainly buy pre-made gesso or purchase a canvas or panel that has already been pre-gessoed, making the primer from scratch is also an option. "Sometimes you want to use the raw ingredients, not merely to learn how to make a perfect batch, but also to understand how it's made, and then alter or amend future batches so that they further enhance your art's uniqueness," says Kimberly Brooks, contemporary American artist and author of The New Oil Painting: Your Essential Guide to Materials and Safe Practices

Materials You'll Need

  • PVA Size, such as Gamblin's PVA Size, Golden GAC 100, or Golden GAC 400
  • Chalk dust
  • 400-grain sandpaper 

Step-by-Step Instructions

  1. Add one layer of PVA size to your substrate, then let it dry. Brooks says you'll know it's completely dry when it's no longer cold to the touch. 
  2. Next, mix one part PVA size with one part chalk dust (the dust should have a fine, not coarse texture).
  3. Add the equal parts PVA size and chalk mixture to your substrate and let it dry.
  4. If you prefer a more opaque base, stop there. For those who like a milkier, thicker texture mix two parts chalk with one part PVA size and add a layer to your substrate. Let it dry. 
  5. Continue adding layers of the two-to-one mixture until you have the desired whiteness and thickness you want.
  6. When you're done adding layers, sand the dry gesso with 400-grain sandpaper until smooth.

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