I just finished building a rough sawn douglas fir porch cover with my contractor. Unfortunately, when he cut the bolts with the grinding wheel, it left a residue of either burnt metal (or the aluminum oxide grinding disc dust). He came back and sandblasted it, but some of it, and a little bit of grease from the grading chains at the saw mill remain. Any suggestions?
Not sure on how to remove the grease or the burnt metal. Deck cleaners will not remove it.