Varnishing your oil painting is essential for protecting it from environmental damage, enhancing its colors, and giving it a professional finish. Varnish acts as a barrier against ultraviolet light, atmospheric pollution, and abrasion. It’s composed of Damar resin dissolved in turpentine and other organic solvents.
However, timing is crucial. Oil paint dries from the surface inward, forming a skin with microscopic pores. While the surface might feel dry, the paint beneath remains wet for an extended period. Applying varnish too soon can trap solvents and lead to problems like wrinkling, cracking, and yellowing.
Generally, allow at least six months for the oil paint to fully dry before varnishing. This ensures that the solvents in the varnish won’t re-dissolve the underlying paint layer.
Here’s a step-by-step guide to varnishing your oil painting:
1. **Cleaning:** Ensure the painting is free of dust and dirt. Gently wipe the surface with a slightly dampened cotton ball.
2. **Drying:** Remove any excess moisture with a clean cotton ball. Carefully pick off any cotton fibers that may stick to the paint surface.
3. **Rest:** Allow the painting to dry completely for several hours.
4. **Varnish Selection:** Choose between high gloss, satin, or matte varnish, depending on your desired finish. Varnishes can be applied with a brush or spray. A flat bristle brush works well for manual application. For a less shiny effect, opt for a matte varnish.
5. **Application:** Lay the painting flat. Apply the varnish in smooth, parallel strokes from one edge to the other, working in one direction. Maintain a consistent amount of varnish on the brush for even coverage. Varnish the entire painting in one session to avoid unevenness.
6. **Second Coat (Optional):** Once the first coat is dry, apply a second coat at a right angle to the first for a uniform finish.
7. **Initial Drying:** Leave the painting flat for at least 10 minutes to prevent varnish runs. Then, prop it up against a wall, facing inward, to dry.
8. **Complete Drying:** Test for dryness by gently touching the edge of the painting. The varnish should be dry to the touch within one to two days, depending on weather conditions.