Odd thing happened sawing oak

[cutterboy]

Hi everyone. I was sawing red oak today and an odd thing happened. Several of the boards got blue speckles all over them. I've been sawing oak for many years and I know that the combination of steel, water and the tannins in oak will leave that nasty dark blue color on the lumber- I know that. So, for several years I've been sawing oak dry, I mean I don't run water on the blade when I saw oak. Today I was sawing dry as I usually do and the lumber got blue speckles on it. It was not raining, but it was cloudy and humid. Do you think the moisture in the air would be enough to turn the oak blue?

Here, take a look.

[Jeff]

The moisture within the lumber is all that is needed. What steel was the lumber in contact with?

[Ron Wenrich]

I sometimes would get that after filing the saw and some metal filings got on the boards.  I'm running a circle mill.  Is there something worn that could be shedding filings onto the boards? 

[doghunter]

check for a bearing goinbad or a steel to steel clearance problem those speckles are definitely from metal filings

[cutterboy]

I think you guys may be right about metal filings. I never thought of that. I had problems with one of my blade guide rollers today. At one point it stopped turning and I saw small sparks shoot from it as the blade ran over it. I ended up replacing it but not before I had sawed most of the log.

Thanks guys, good call.        Ralph

[tyb525]

When I saw oak I use water, and there is enough of a reaction between the steel from the band, the water, and the tannins to cause a blue stain on the sawdust left on the board. It doesn't usually stain the board unless I don't get it knocked off soon enough.