Water stain on new oak??

Mikeyorks

Just putting the finishing touches to a small conservatory. Unfortunately the idiot who fitted it had to come back after we'd started the internal woodwork. Fortunately managed to get the oak floor fully sealed.

But, despite dust sheets everywhere, I've now got two water stains on 1 of the (3) oak window cills. As the cills are biscuit jointed and stuck down - I don't want to attempt to take it off. So need to try and fix it 'in situ'.

One of the stains is just circular and has (it's European oak - so light in colour) virtually sanded into the background. But the other is from a drip from one of the pushout windows (how does an experienced fitter manage to block the vents in a d/g window with the spacers?? So the window fills with water [it's leaded on the outside so does let a lot into the frame] .. and 'overflows' inside??) and has really splattered all over the cill.

A damp cloth dragged across the whole of the cill? Just sand it (tried it once and it really does still show)? I don't think I want to try woodstain as I don't want to darken the oak.

Any ideas, please? The sealer is an oil based one and will probably diminish the marks - but I don't want to try that except as a last resort.