This is the best way I’ve found so far to clean the interior side of the original (extremely hard) white oak hand hewn logs. This is the Northwest second floor corner. Since this was eventually turned into a formal entry way, long before the plaster was installed over the logs, they were given various coats of whitewash white paint, in order to make the walls look like they were plaster, rather than logs. Such was the trend, since there was nothing glamorous about having a log plantation house.
It’s a lot more work than power washing it, but I’m trying to avoid introducing water to the inside of the house. I’m also trying to be very conservative in any preservation work to the logs. This seems to do the trick. It’s just time consuming. I may also experiment with sand blasting or walnut shell blasting, if I can ever get my blaster to work.