Oil vs Watercolor: The Fundamental Difference Every Painter Must Know

When I started painting, I made every mistake in the book. But the biggest revelation came from understanding one simple principle that separates oil painting from watercolor.

The Oil Painting Approach: Dark to Light

With oils, you have complete control. You can paint over anything, adjust anything, fix anything. This gives you a specific workflow:

1. Tone Your Canvas First

Never paint on white canvas with oils. Cover it with a neutral mid-tone—burnt sienna, yellow ochre, or a warm gray. This does several things:

Eliminates the intimidation of a blank white surface

Gives you a middle value to judge lights and darks against

Creates unity throughout the painting

Shows through thin paint areas, adding warmth

2. Establish Your Darks

Start with your darkest values. Block in the shadows and dark masses first. Oil paint is opaque—you can always paint lighter colors on top, but it's harder to go darker over light.

3. Build Up to Lights

Work progressively lighter. Save your brightest highlights for last. This layering creates luminosity because light passes through thin upper layers and bounces off the layers beneath.

The Watercolor Approach: Light to Dark

Watercolor is the opposite. The white paper is your light source, and you can never get it back once it's covered.

1. Preserve Your Whites

Before you touch brush to paper, identify every area that needs to stay white or very light. These are your highlights, your brightest spots. Once they're gone, they're gone.

2. Start with Light Washes

Begin with the lightest values across the painting. Watercolor is transparent—darker layers will show what's underneath. Starting light gives you room to build.

3. Build Darkness Gradually

Each layer should be slightly darker than the one before. Let layers dry completely between applications to maintain clean colors.

Why This Matters

Understanding this fundamental difference will:

Save you from muddy watercolors (trying to lift out highlights that are gone)

Save you from chalky oils (putting too-light values on too early)

Help you plan your paintings before you start

Make you more confident in your approach

The Common Thread

Despite these differences, both mediums share one truth: value is more important than color. A painting with correct values will work even if the colors are wrong. A painting with incorrect values will fail even with beautiful colors.

Start by getting your values right. Everything else follows.