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The Alchemy of Oil Painting

What is oil paint?

Oil paint is an art medium made up of dry color pigments suspended in drying oils, traditionally linseed oil. Some pigments are natural, some are lab-produced.

Where’d it come from?

Oil paint surpassed the more finicky egg tempura as the most popular easel painting medium during the Renaissance (1350 - 1620 C.E.) With oil paint, paints could now be saved and transported instead of having to be mixed on the spot. It also allowed linen canvas to replace wood panels as the most commonly used painting surface. Because it is purely pigment suspended in oil , oil paint surpasses all other painting mediums in its tonal depth and color intensity.


What can we paint on with oil?

  • Wood Panel

  • Canvas

  • Thick watercolor, rag, or printing paper (I only recommend paper for practice or studies but it is a good way to save money while learning)

  • A myriad of new age materials (I personally love clay board - it’s pricey though)

*You can buy already primed canvas, boards or canvas paper if you want to get started right away. The benefit of priming your own surface is that you can reduce costs and you can control your surface texture. I apply a coat of gesso even if I buy a primed canvas to reduce the weave texture that bought canvas tends to have.

Do I have to prime?

With oil paint you do have to prime the surface or the oil from the paint will leak out of the paint and into the material - deteriorating both the material and the integrity of the paint itself. Eventually, the paper,canvas, or wood will deteriorate. The paint will not cure properly.

Types of Primers:

  • Gesso - has a smooth, plaster-like texture, vegan

  • Rabbit skin glue - has a rough texture, made the way it sounds

  • Lead white - toxic, rarely used today

  • Alternatives - today there are a myriad of primers with different textures that you can experiment with. Make sure you do your research and that it is intended for oil paint.

*If you love animals and want to reduce any toxic exposure, like me, Gesso is the easy choice. Some are still made with animal glue but most are water based and made by combining glue and white chalk or plaster of Paris. The more expensive the gesso, usually the thicker and smoother it is.

Steps of Priming:

  1. Stretch canvas, prep wood panel, or tape paper edges with artist tape.

  2. Wipe with a damp rag to remove any dust.

  3. Apply a thin coat of gesso, moving a large brush in consistent strokes in the same direction. If working large, make sure to start applying gesso in the middle of the stretched canvas and work out to the edges to avoid warping. Don’t forget the corners and edges!

4. Immediately wash your brush. Once gesso dries, it is like plaster. You can use warm water and dove soap. Dove soap bars work just as well as fancy brush soap.

5. Let the first coat of gesso dry for at least one hour.

6. For a very smooth texture, lightly sand the first layer of gesso and wipe with a damp rag. You may want to wear a mask to prevent breathing in the gesso dust.

*If you’re working on paper, I don’t recommend sanding.

7. Apply the next layer of gesso, moving your brush with strokes in the opposite direction as your previous layer. I used vertical strokes in the first layer, so I’ll use horizontal strokes in the second layer.

8. Repeat steps 3 - 6 to create the surface texture that you want to paint on. I always do at minimum 3 coats of gesso. The more you do, the smoother you can make the surface.

9. Let your surface dry for at least 24 hours before getting started with oil paint.

*Some artists stretch their paintings after they are finished. You can do this but you risk cracking the priming layer.

*With paper I use my drawing board and tape the edges with artists’s tape for a clean finish. Paper is great for studies & lessons.

Let’s Paint!

Most oil painters use washes, pure oil paint, glazes or any combination of the three to create their masterpieces.

Wash: A wash is the thinning of the oil paint with turpentine or odorless mineral spirits. I recommend odorless mineral spirits as they are much less toxic.

Pure Paint: Paint straight from the tube, with nothing else mixed in.

Glaze: A glaze is when you extend the oil paint by adding more oil. Traditional glazing mediums are linseed oil, safflower oil, or walnut oil. Today we have some pretty amazing mediums that both extend the oil paint as well as help it dry faster like Galkyd or Liquin. I prefer Liquin because it has more gloss, dries a little more slowly, and is less tacky in texture.

Fat Over Lean Rule:

Working in layers to build up an image is a wonderful possibility when oil painting. You can use washes and glazes to create transparent layers of color that build up to make dynamic tonal and chromatic relationships. To ensure that paint dries properly and prevent any cracking or slipping, we have to follow the rule of fat over lean.

  1. Begin with LEAN layers. Lean layers are layers where the paint is thinned into a wash with odorless mineral spirits or turpentine. You’ll notice that the chroma (color intensity) is diluted in a wash.

  2. You may want to move into working with paint straight from the tube from this point or follow the next step if you want to work in semi-transparent layers.

  3. For the next layer, mix a little of your FAT into the mineral spirits. Your fat is your oil or medium - linseed oil or Liquin, etc. Depending on how many layers you want to work in you might do a 75% lean 25% fat or 50% and 50%. Use this mixture with your paints to make them more fluid.

  4. In each successive layer, add a higher proportion of fat to your paint until you are only adding your fat element (Liquin) to the paints (no spirits or turpentine).

  5. Finish your oil painting layers by glazing. Glazing is when you use your fat element to extend the viscosity of your oil paint. You’ll notice that differently from a wash, a glaze does not lose any chromatic intensity, it just makes the paint more transparent with the more fat that you add.

Below is an example of how you could build up layers in an oil painting. You can do as few as one layer up to an infinite number. Just remember: Fat over Lean!


Why do we varnish?

  • Varnishing brings back the original luster of the painting, how it looked when it was wet and you first painted it.

  • It increases chroma intensity as well as tonal depth - it especially deepens the richness of dark colors.

  • It protects the painting from dust, elements, and deterioration.

  • Galleries prefer varnished paintings.

  • Makes the painting easy to clean. Varnish comes in gloss, matte and satin textures. I recommend Gamvar Gloss Varnish.

Varnishing steps:

  1. Wait until your painting has dried and cured. This can take anywhere from 2 weeks to 2 years depending on how thick your paint layers are. *Gamvar is a special varnish made by Gamblin that can be applied to your painting as soon as it is thoroughly dry to the touch. Wait at least 6 months if using any other varnish.

  2. Clean your painting with a lint free rag - like the kind you use on glasses. Get everything! Every hair, every speck of dust! Anything left will be varnished onto your painting forever. Varnish in a clean area with paintings laid flat.

  3. Pour your preferred varnish directly onto the painting, creating quarter sized pools in different areas. Be conservative because you can add more.*Some people prefer dipping their brush in a separate jar with varnish. I find it turns out less even.

  4. Use a fresh foam brush to drag varnish across the painting - extending your pools so that the entire painting has a thin, even coat. You need a fresh foam brush (preferably) or a brush dedicated to varnishing that has soft bristles. I usually batch varnish when I have a few paintings ready at the same time, using a new foam brush.

  5. Get on level with your painting.Make sure that you have coated every inch and that the varnish is even. Fill in any dry spots. Pull your foam brush across the entire painting - moving in the same direction to ensure an even coat. Thinner is better! Check for any hair/dust that may have fallen on the painting during varnishing - remove with tweezers.

  6. Leave in a clean space, preferably well-ventilated, with your beloved fur babies kept out. Gamvar will dry between 24 and 48 hours. During this time, we want to minimize the risk of anything falling into the varnish and curing onto the painting. Other varnishes will take longer to cure.

  7. Once the varnish is dry to the touch, you can repeat steps 2 - 6 if you would like additional layers. I recommend keeping your layers thin and building them up. You may experience a “dry spot” which is just an area where they varnish got missed. Don’t panic! Just do another thin layer, and make sure you focus on that “dry” area.

*I have had devastating things happen when moving freshly varnished paintings when it is very hot or humid. I prefer to have varnishing finished 2 weeks prior to moving my work, ESPECIALLY in the summer. If you have to move it sooner - do not stack paintings! I’ve had them weld together in a hot car.

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