I have black raised dots on my white cedar shingles that have semi-transparent stain on them. They're only 3 years old.
I'm having a hard time removing the dots.
I've tried bleach as well as other products but nothing works unless I sand it down to the bare wood. Even after sanding you can see little black stains in the wood.
Also when it rains my shingles turn black.
I do have Tyvec behind the shingles and put two coats of stain on them.

Help?

black dots on shingles

dots