The stain found mineral spirits, therefore it was oil based.
It will help to diagnose the issue first, before starting the cover up. You need to contact the producer of the stain you utilized. Because of so many variables involved, it’s tough to figure out from your explanation whether this’s a product failure or maybe an application problem.
And also the black spots might not be mildew. Eggert states that tannic staining from redwood as well as cedar looks exactly love mildew and actually passes the bleach evaluation.
Bleach is going to kill mildew and help make it disappear, and it’ll perform the exact same with tannic acid.
There’s one other factor going on with these. Exterior semi transparent stains are nothing more than thinned down paint.
Then allow it to dry. Eggert stresses this particular part especially. Among the possible reasons for the original issue would be that the siding might not have been completely dry when you 1st applied the stain.