Knot questions

[Chris152]

I picked up a piece of walnut and a piece of lime today (i've never used either before and wanted to see how they are to work with), both have knots that make we wonder.

The walnut has a strange (to me) structure at its centre/ pith - is this normal, and is there a name for it? It's in a few knots along the board.

And the piece of lime has a pretty normal knot on one face, but the other seems to have collapsed as it's dried:

Any ideas what the cause of this might have been?

Thanks

Chris

 

[MikeG.]

First of all, you'll love working with walnut. It's an absolute dream, especially if you have only worked with pine and oak.

The knots both look to me like they may have been branches that were lost whilst the trees were still standing. The walnut one looks as though it may have rotted a bit, and the lime looks as though it has healed up between the branch coming off and the tree being felled. It is hard to tell from the photos, though, and I wouldn't be at all surprised to be 100% wrong.

 

[Chris152]

Thanks Mike - the walnut knots/ rot makes sense to me. The lime tho is less clear - the photo doesn't show it well, but across the collapsed side of the knot are complete saw marks that have now sunk into the recess, which means the collapse must have happened after sawing when it dried - maybe it was already rotten but on drying collapsed? It does look odd, though.
Cheers
C