I stained this 2 years ago before installation - back and front. The boards were kiln dried and stained inside. The penetrating stain I used contains linseed oil and after I installed I read some reviews saying the stain wasn't very good. I had hoped my cedar being in the soffit would not have any problems but there goes that.
This is the worst one but you can see signs of mold on the others. I tried sanding with 150 grit but the mold seems wet and just smudges.
What would you sand with? or would you scrape it? maybe steel wool it? I could go for a dish sponge? I haven't done much work with stain grade wood so any advice appreciated. I currently have scaffolding up so now is the time to fix if there is a time. I don't think I'll spend time on the lesser effected boards unless there is something easy, maybe a topical mildicide? I can't see sanding / staining 140 linear feet at 2' depth being worth while until the lesser effected boards look much worse even then maybe I go with it and stain black.