When is dry rotted sapwood a concern?

[Eddie Wilson]

I purchased some air-dried lumber from a local lumber guy, walnut slabs. I noticed that the sapwood on the edge (1 or so inches thick) was dry rotted. I can break off a bit by hand, with some force. I planed a bit of the heartwood and it looks great. In contrast, I've purchased kiln dried lumber from another local guy, and the sapwood seems to be just as strong as the heartwood. I see people incorporating walnut sapwood into their projects with beautiful results. 

Should I be concerned about dry rotted sapwood? Is this the difference between air-dried and kiln-dried? How safe is it to incorporate walnut sapwood into your projects?

[wdwerker]

Sapwood could have been dead before the tree was cut. Or it could have been exposed during air drying and degraded.

[Bmac]

Walnut heartwood is very resistant to decay, you can use that with no worries. Wood that is resistant to decay (cedar, locust, osage, walnut, etc) all have sapwood that will decay. The heartwood is what is resistant to decay in wood. As Steve mentioned above, the sapwood was likely rotted/decayed when the wood was milled. There is a slight, but very small chance the sapwood decayed during the air drying. Lets put it this way, correct air drying technique will not cause degradation of the sapwood.

Decay and rot cannot occur in wood if it is deprived of moisture, so once dried if the sapwood is solid than you can comfortably use it with your projects. The only caveat would be that the project will not be used outside. If building an outdoor project with decay resistant wood, I'd try to eliminate all the sapwood prior to construction.

With this air dried stuff you purchased, you will need to cut away all the rotted sapwood and just use the heartwood, but you can use the heartwood with confidence. 

  

[Chestnut]

Bmac beat me to what i was going to say.

[Eddie Wilson]

Thanks you for the detailed answer Bmac. Explained everything perfectly.

[Pondhockey]

I like Bmac's explanation.  I will note that an outdoor table that I made a few years ago with Western Red Cedar, that was treated with Clear Penetrating Epoxy Sealer, and then with spar varnish - and kept under cover - has lasted quite well (both the sapwood and heartwood.)

That doesn't conflict with what Bmac said.

[Ronn W]

I learned something.....again!

[Tom King]

I built our Walnut kitchen cabinets out of Walnut that came from a standing dead log.   The sapwood had long ago rotted completely away, and it had been struck by lightning.  That was when I was young, and foolish, and had I known how much work, and waste there would have been, I would have just bought wood.  There was absolutely nothing wrong with the wood I was able to use though.