How to Treat Pine for Outdoor Use

Pine is the wood of choice for amateur and artistic woodworkers. It is relatively cheap, easy to cut or shape, and widely available. 

On the flip side, pine is also one of the most difficult woods to finish. It is an unevenly porous wood, making it difficult to absorb finishes evenly. The finish usually soaks much deeper into the larger earlywood pores than in the dense and smaller latewood pores, causing the former to be darker than the latter.

Due to this uneven distribution, painting is regarded as the most effective means of treating pine. Alternatively, you can apply several coats of polyurethane. Gold old poly will allow light to shine through it, maintaining the wood’s natural aesthetic. You could also opt for tinted poly if you wish to make the wood’s shade more vibrant

How to Treat Pine by Painting

Combined with a formidable sealant, paint forms an impervious layer that retards moisture movement out or into the wood and offers significant protection against contamination. Also, painting is particularly advantageous in pine because paint color balances the wood’s uneven grain staining. 

Applying Paint

The first step is to choose your paint. Apart from color, you should also choose between oil-based and latex paint. Woodworkers with pressure-treated pine should go for latex paint, while those with untreated pine should choose oil-based paint due to its enhanced moisture-resistance capability. 

Next, use fine-grit sandpaper to gently sand down the wood’s surface. Rub the wood in circular patterns to achieve a smooth surface and pay particular attention to uneven regions. Use a wet, soft cloth to wipe off wood shavings. Afterward, apply thin, even layers of primer on the entire surface and let the wood sit for at least one hour. Once the primer is dry, apply three coats of paint at intervals of one to two hours for each coat to dry. Complete this process by evenly spraying paint sealant for an impermeable yet glossy finish. 

How to Treat pine using polyurethane

As we mentioned in our outdoor wood treatment guide, poly is the best finish for exterior lumber because of its superior pore-sealing capability. It is an ideal treatment agent for pine, although you will need to take specific measures to minimize the uneven staining problem. 

Applying Poly

Start by sealing the wood surface with diluted poly. Use mineral spirits to thin a portion of your poly at a ratio of 1:2. This sealant solution gives the poly added durability and allows it to stick better. Use a paintbrush to gently apply the sealant in lengthy strokes across the wood grains. Give the sealant 24-36 hours to dry before applying pure poly to the surface. Ensure you spread out any drips using the brush before the coating dries. Apply at least two coats of poly, allowing each enough time to dry. 

The wood’s surface will likely have uneven areas and poly bumps after all the coats are dry. In this case, use a sharp blade to slice off the bumps and a 400-grit abrasive sheet to sand down the uneven regions. Wipe off the dust and shavings using a wet cloth. Finish off by applying a final coat of poly. 

Conclusion

In sum, pine’s uneven pore distribution is a major inconvenience for woodworkers intending to use this wood for outdoor purposes. This feature prevents the wood from evenly absorbing finishes and staining accordingly. Painting offers a good solution to this predicament as paint color balances the uneven sheen. Another viable option is applying polyurethane as it provides the wood with an additional protective coating without concealing its grains and patterns.