We started building our log home last summer. Before getting the roof on last fall, we had many days of rain. Over the winter, the logs have turned a grayish black on both the inside and outside. A few of logs have what I think they call ”blue stain” in parts of the log. They are white pine logs. We just had the interior cob blasted and it left a fussy finish. The surface color drastically lightened, but the fuss on the surface does still appear gray in areas. We are planning on sanding an
You will need to sand the entire interior for a desirable finish to keep clean. Perma Chink makes a product called Wood ReNew that may take some of that black out. Blue stain is caused from the logs not being peeled soon after harvest, and goes all the way to the heart of the log. Not much you can do for it.