Linseed oil on outdoor projects?

Our expert answers

Thanks for your question Paul. Raw linseed oil is generally not recommended for outdoor projects. One of the main drawbacks is its very slow drying time — it can take days or even weeks to fully cure, especially in cooler or more humid conditions. Additionally, it doesn’t provide much protection against the elements, such as UV rays, moisture or mildew. Because it remains tacky for a long time, it can also attract dirt and promote mold growth.

If you’re looking for a better option, boiled linseed oil (BLO) is a more practical choice, as it dries much faster. However, even BLO isn’t the most durable option for outdoor use. Pure or polymerized tung oil provides better water resistance and durability, though it still requires regular maintenance.

For the best protection, consider using a finish specifically formulated for exterior use, such as Penofin, Watco Exterior, or a marine-grade spar varnish or oil blend. The best finish ultimately depends on factors like the type of wood, the level of exposure to sun and rain, whether you prefer a natural or glossy look, and how often you’re willing to maintain the finish.