As I look for a finish for my log home, I find many natural options: linseed, tung, pine rosin etc but what concerns me is maintaining a breathable finish. Does an oil finish like linseed reduce vapor permeability to a significant degree?
On an interior wood finish, I would also assume an oil like linseed would reduce hygroscopicity.
Any suggestions from experienced biological builders here on how to maintain vapor permeability and hygroscopicity of a log home?
Natural oil finishes do allow breathability and the hygroscopic nature to continue, but do slow down the reaction to environmental changes, the slowing effect deceased as the finish ages.
Things like boiled linseed oil, and Danish oils have "dryers" added that help dry the oil faster, and these tend to leave a heavier surface film, so their effect is greater, but the dryers are toxic and often contain heavy metals, so wiegh out your goals.
Commercial stains and finishes are the next step up in both moisture protection and chemical warfare.
One note please do not throw oil rags in a trash can, hang them to dry then despose of them safely, oil rags can spontaneously combust!
Companion Planting Guide by World Permaculture Association