We discovered this wood spotting problem and are hoping someone can provide a bit of insight, recommendation, non-toxic fixing ideas, etc. There were two areas where this appeared:
On the floor. This was 2x6 tongue & groove pine that we sanded and sealed with a product called AFM Watershield. The black spotting showed up near the edge of the platform, in certain areas between where we put up the snow & wind kit support rafters. We did have a good bit of rain while we were putting the yurts up, though we did our best to dry the floor before continuing with assembly.
On the yurt door. The doors are Douglas Fir and were treated by the manufacturer - Pacific Yurts. The black spotting seems to be occurring near the metal pieces of the door as well as near some of the lower pieces.
Pictures below. Any suggestions, send us an e-mail.