How deep does this stain go in this walnut slab?

[bradleyheathhays]

I'm surfacing this 2" walnut slab on the CNC, and I'm wondering what this dark coloring is on the lighter sap wood and how deep it goes? I don't have a lot of experience with walnut, and I haven't seen this kind of coloring in other peoples' projects, so I don't know what to think.

Will this unwanted dark color possibly lessen as I take more layers off?

 

[jttheclockman]

Turn the board over and see if it is on the opposite side. Probably is. All part of the sap wood in that tree.

 

[Seer]

I have worked with a lot of Walnut and this is normal not a stain.

 

[darrin1200]

I believe that is, what I call, old wood.
The tree may have been on the ground for some time before being harvested. I think this is the wood being affected by moisture from the ground. A long way from rotten, but starting to colour.

 

[leehljp]

The gray streaks are moisture related oxidation and fungal reaction. Usually this is seen in the white sapwood. If you want to see it even more pronounced, go cut a large holly limb (or tree) in the late spring and cut it into a board. Within a couple of weeks, the white holly will be gray from the excess sap in a fungal reaction. In some cases it affects the spalting in different woods.

The reason you see it in the white wood of the walnut is that there is more moisture traveling in the white sap wood than the brown and (I have been told by several over the years) - wood cut in the spring and early summer will be more likely to have spalting or graying in the sap wood because more moisture is traveling through it at that time. Again, I have been told that if I want white holly to stay white, cut the tree in the late fall or winter. I don't know how true that is but I have heard it more than once.

 

[leehljp]

BTW, the graying of the sap wood can be found by Googling: "Why is the white sap wood turning gray?" But, I learned it the hard way by cutting a neighbor's small holly tree in the early summer (at his request) and seeing the white holly turn gray within a couple of weeks, destroying its value to me!