To effectively paint over a charcoal drawing on canvas, the key is to fix or stabilize the charcoal lines first to prevent them from smudging and mixing into your subsequent paint layers. Based on traditional methods, a reliable way to prepare your charcoal underdrawing for painting is by tracing over the charcoal lines with lean oil paint like raw or burnt umber.
Preparing Your Charcoal Underdrawing for Painting
Charcoal is a powdery medium that can easily lift or smudge when paint is applied over it. To avoid muddy colours and preserve your drawing lines, it's essential to fix the drawing before you begin painting in earnest.
Method Using Lean Oil Paint (Based on Reference)
A time-tested technique involves using lean oil paint to create a stable layer over the charcoal lines.
- Ensure Drawing is Complete: Finalize your charcoal drawing on the canvas.
- Prepare Lean Oil Paint: Thin a small amount of oil paint with a solvent like mineral spirits or turpentine. Colours like raw or burnt umber are often used for their transparency and earthy tones, which can work well as an underlayer. The goal is to make the paint "lean" (more solvent, less oil).
- Trace the Lines: Using a fine brush, carefully trace over the charcoal lines with this lean oil paint. This encapsulates the charcoal dust and creates a permanent line.
- Allow to Dry: Let this lean oil paint layer dry completely. This can take a day or two depending on the paint and ventilation.
Once the lean oil paint lines are dry, they effectively seal the charcoal, providing a fixed guide that you can then paint over without disrupting the underdrawing.
Traditional Alternatives
Historically, artists also used other methods to fix charcoal underdrawings before painting. As the reference notes, artists would traditionally go over the charcoal lines with sepia or bistre ink. While this is an ink-based method rather than paint, it serves the same purpose of fixing the drawing.
Important Considerations
- Lean Over Fat: When working with oil paints, it's crucial to apply 'lean' layers (more solvent, less oil) before 'fat' layers (more oil). Tracing with lean paint adheres to this principle, creating a stable, fast-drying base.
- Complete Drying: Ensure the traced lines are thoroughly dry before proceeding with your main painting layers. Painting over wet or semi-dry tracing lines can still cause smudging.
- Minimal Charcoal: For best results, keep the initial charcoal drawing relatively light. Excessive charcoal can be harder to fix completely.
By tracing your charcoal lines with lean oil paint as described, you create a stable foundation on your canvas, allowing you to paint over your initial sketch without fear of the charcoal interfering with your colours and brushstrokes.
