This may start off by discussing the differences between the Pine Tar options but the conversation is ultimately going to be about a light finish vs. a darker finish.
Many out there want to use a finish that maintains the natural color of the wood. In other words, they are hoping to preserve what the wood looked like on day of install. Completely understandable of course as it feels like the best way to celebrate the beauty of the material.
For interior surfaces, this is often possible.
For exterior, it is more complicated.
A light finish does not offer much UV protection. The Purified Linseed Oil, for example, can be used as a finish by itself and while it provides excellent moisture protection, it lacks important UV protection that will prevent natural weathering and aging of the wood surface over time.
If you add another traditional coating in combination with the Purified Linseed Oil, then the best protective and preservative properties can be achieved.
A perfect example of this is the Light Pine Tar vs. the Dark Pine Tar.
Authentic Pine Tar has naturally occurring resins and terpenes, making it an excellent exterior wood surface preservative.
While many gravitate towards the Light Pine Tar for their exterior siding, the long-term protection and visual integrity of the substrate will greatly benefit from the use of the Dark Pine Tar or one of the Pigmented Pine Tar options.
Now what are the biggest downsides to a light finish with little UV protection?
The ultimate goal here is to protect and preserve the wood that is in turn protecting the structure (a home we may very well live in) from the elements. We must consider the impact of exposure on these surfaces in order to ensure the material can continue to fulfill that purpose for many years to come.
Wood that is bare or has a very light natural finish is better off than if a modern plastic paint or stain was used - at least moisture can move back and forth within the substrate based on seasonal changes.
That said, bare wood or a very light, natural finish will weather or discolor over time as exposure breaks down the lignin in the wood. Sometimes this natural aging can be quite beautiful but it is slowly impacting the integrity of the wood. This process may happen over a long period of time but the end result is the same: deterioration.
If natural pigmentation effectively improves and strengthens the wood overall, it makes sense to include it in the protective coating whenever possible.
Take a look at the projects below for an illustration of this relationship:
The image on the left is a 50/50 ratio of Light Pine Tar and Viking Purified Raw Linseed Oil. The image on the left is a 50/50 Dark Pine Tar and Viking Purified Raw Linseed Oil.
As you can see, the light finish has held up well and while there is no wood rot or significant deterioration, discoloration from splash-back is evident after a 5 year period. A darker finish would help offset these environmental factors considerably; in the short-term, as well as, in the long-term with reasonable maintenance.
Consider this dynamic when you are deciding on the best Pine Tar option for your project.
A Light Pine Tar finish can always be maintained, or in other words, transitioned to the Dark Pine Tar and Purified Linseed Oil if needed but labor, time, and the overall integrity of the wood will all benefit from the choice of a slightly darker finish from the onset.
Now how about a compromise? A popular option is a higher ratio of Purified Linseed Oil to Dark Pine Tar. This will create a lighter finish, but still offer more UV protection in comparison to the Light Pine Tar and Purified Linseed Oil mixture.
The same principles apply of course – avoid going too light when using the Dark as the lighter you make it, the less UV protection you can expect.
Questions? Reach out via info@earthandflax.com and visit our Pine Tar product page for more information on application suggestions.