Ugh...BIRDS!!!

[SPitz]

We tried the diluted acid route but that didn't work. My PB thinks it will start to come out with the acid wash and brushing but I am not convinced. Not to sound too crude here, but birds eat berries and what goes in one end, comes out the other. The droppings were a blue berry color and now the stains look brown. Maybe they will come out, I sure hope so. Someone on another forum suggested wet sand paper...any thoughts on that?