Gesso, Whites and Glazing Medium for Acrylic Layers

Gesso, White Mixing and Glazing Medium in Acrylic Layering

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Gesso basics

• Modern gesso is acrylic primer plus calcium carbonate (chalk) and pigment. Traditional gesso is rabbit skin glue plus calcium carbonate, made to seal canvas from oil paint.
• Gesso seals, primes and adds tooth on paper, wood and canvas.
• Student and artist grades differ in pigment amount and in how finely pigment and chalk are ground. This affects coverage and smoothness.
• Colors available: white, black and clear. Viscosities vary by brand, so test brands and viscosities for the surface texture you want.

Storage

• Buy gesso in bottles for easy dispensing. Decant jar gesso into airtight art or hobby store bottles.
• Bottles that don't seal tightly let the gesso dry out.

White gesso (surface prep)

• Liquitex Professional Gesso is pourable. One coat covers paper. It is also suited to adjusting paint opacity.
• On Yupo, gesso adds tooth and slight absorbency. This gives more control of wet paint than bare Yupo.
• Coat nonabsorbent Yupo with gesso to increase absorbency.
• Coat traditional watercolor paper with gesso to make it less absorbent.

Black gesso

• Golden black gesso covers white paper (Yupo or watercolor paper) in one coat. It is archival and won't fade.
• Transparent paint cannot cover a black or dark surface. Build up with translucent and opaque layers.
• It can replace black acrylic paint. Black gesso dries matte, where black acrylic dries glossy, and it keeps some absorbency from its tooth.

Clear gesso

• It has considerably more tooth than other gessoes and dries clear to translucent.
• Coat Yupo with it for more tooth than white gesso gives.
• Mix it with acrylic paint for custom color.

Mixing gesso with acrylic

• There is no chemical problem mixing gesso with acrylic paint, and it is cheaper than white paint.
• Gesso plus transparent acrylic gives an opaque or semiopaque paint with a flat matte finish.
• Best results come from fluid paint plus low viscosity gesso.
• On black, mix white gesso into transparent paint to get opaque or semiopaque coverage.
• For a glossy opaque finish, use Titanium White acrylic instead of gesso.

Choosing a white

• White gesso, Titanium White and Zinc White acrylic can each be used alone or mixed with acrylic for opaque or translucent mixtures.
• White gesso: covers about like Titanium White. Dries matte.
• Titanium White: covers about like gesso. Dries semigloss.
• Zinc White: very transparent, about 1/10 the tinting strength of Titanium. Dries semigloss.
• White gouache: very opaque and dries matte. It stays soluble once dry, like watercolor.

Mixing whites with color

• Gesso and Titanium White both lighten the color and raise opacity, in proportion to the white-to-color ratio. Enough white makes the layer fully opaque but pastel.
• For a more translucent mix with gesso or Titanium White, use less white, or add glazing liquid with the white.
• Zinc White with transparent color stays translucent. Unlike Titanium, it doesn't immediately turn the color pastel.
• Gouache opacity varies with the amount used.
• Gesso and gouache mixtures dry flat matte. Titanium and Zinc mixtures dry semigloss.
• Alternative to adding white: buy paint of the opacity you want. This avoids lightening the color, but you must check each paint's opacity and buy each opaque color.
• Fluid acrylics range from transparent to opaque, but some colors are opaque only by adding white. Tube paint has more opaque colors, and labels usually state opacity.

Acrylic with watercolor and gouache

• Mixing any acrylic white (gesso, Titanium, Zinc) into watercolor makes the paint layer insoluble. Use white gouache to avoid this.
• Dried gouache over dried acrylic can be lifted off to reveal the acrylic color. The acrylic underneath is not disturbed, because dry acrylic can't be lifted.
• Keep gouache-containing layers thin. Thick layers can crack or flake off when dry.
• Mix white gouache with paint straight from the tube. Diluted gouache weakens the mixture.
• For vibrant hues, use colored gouache rather than white plus watercolor.
• Palette warning: acrylic or gesso on a watercolor palette, or in the wells, cannot be removed from the palette or the paint. Always mix acrylic and watercolor on a separate disposable palette.

Acrylic glazing medium: what it does

• Mixed with acrylic, it extends working time and increases transparency. Thin acrylic dries very fast, so the medium lets you blend layers.
• It is especially useful for translucent and opaque paint on black gesso.
• Added to opaque paint, it gives translucent mixtures that adding white alone can't easily produce.
• Added to transparent acrylic, it extends drying time and increases transparency.
• Golden Open Medium also extends drying time.

Gloss vs satin

• Gloss gives a high sheen.
• Satin gives a slight sheen. It suits gesso mixtures, which dry matte, and blends with thinly applied acrylic when the medium is used in only some areas.

Mixing method on the palette

• Keep glazing medium separate on the palette, not premixed with a palette knife. This lets you adjust the ratio as you paint.
• Load the brush with paint, pull out medium, and blend on the palette before applying.
• Test transparency on scrap paper first. More medium means more transparent.

Gesso + paint + glazing medium

• Load color, blend in white gesso to the value you want, then pull out medium and blend thoroughly on the palette.
• For a translucent mix, use less gesso and more medium. Medium added to a gesso-and-paint opaque mix makes it translucent.

Blending and scraping back

• To blend two colors on the surface, mix medium into both before applying. For example, Lemon Yellow with medium on black, then Phthalo Blue with medium, blends yellow to green to blue. This is very hard without the medium.
• Medium keeps the layer open, so you can scrape back through translucent or opaque paint to reveal the layer or paper beneath. This often helps integrate the layer into the painting.