oak turning black/blue?

[peatff]

Ah I figured it out! The wood didn't change colour until yesterday/day before, a week after cutting it. But I'm trying to clean the place up for Christmas and took the angle grinder to the old load bed off the L200, white thing in the background. It was right in front of the beam, so must have got showered in sparks. Thanks for solving the mystery folks:thumbup1: Quite amazing that a combination of iron filings and the natural tannins can create such a reaction, and is it just iron or do other metals?

 

Steel does it but only because of the iron content in it.

[wills-mill]

If you want a seriously strong version of that colour, have a go at rubbing Oak down with wire wool and vinegar. It stinks and you'll need gloves!