Have you tried Oxalic on it?BlowingOldBoots wrote:When the teak of the hatch coaming has been heavily stained by water leaking in through old hatch mounting holes (which had been filled with mastic that had since shrunk), don't waste time sanding the stains away. The stains penetrate deep into the wood and one would be better (and faster) making new coamings even when the wood is sound on the original coaming.
It is excellent for bleaching and restoring marked or faded wood.
C_W

