Blue streaks in glue squeeze-out

[Winston Chang]

I needed to extend a board, so I cut it at an angle and made a scarf joint. When I glued it together and clamped it together, I saw that some of the glue that had squeezed out had bright blue streaks in it! Has anyone seen this happen before, or know why it happened?

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On the other side, I don't see any of the blue coloration in the squeezed-out glue.

The board is cedar, and the glue is Titebond III. When I put the glue on, I used a credit card to spread it, and it looked normal. I didn't notice anything strange about it. For the cut, I used a track saw, then cleaned up the surface a bit with hand planes. Again, it seemed completely normal.

[Winston Chang]

I just had a head-smacking realization: when I marked the line for the cut, I used a pen so that I'd be able to see it easily on the rough-sawn lumber. A blue pen. I must have gone off the line by a little bit when I made the cut!

[Stan Calow]

Good catch! I sometimes use a pen to mark, so that's a good tip to remember.

[Matt Day]

That’s funny!

[Winston Chang]

That’s funny!

Glad to provide some amusement!

[Chris Fournier]

And that's why I use pencils! Good story and detective work.