Black stain in black walnut heartwood - what is it?

[Eric Weis]

Hi all,

I almost posted this to the sawmill section but it seems a bit more appropriate here. The other day I passed by a huge black walnut that was taken down due to roadside
clearing for an expansion project. the next day I stopped to investigate further and ran home to grab the new saw - yes this was a first cut on a new Husky saw. Has to break it in
somehow... Anyways, upon further inspection after taking 3 slices home for possible tables, I see that black stain. It's in all three slabs, works its way all the way up the tree
as well. I took home some big logs yesterday just for fun and noticed that stain in o log too. Any ideas what that could be? It hasn't hurt the structure or integrity of the
heart wood at all as best I can tell. I cut the slabs a minimum 6" thick. They were very water logged and HEAVY - like 150 pounds heavy. Almost didn't get them in the jeep that day. I guess it will have
to add to the uniqueness of the wood at this point.

Thoughts? I've never seen black walnut with a black stain like that.

Thanks!

[John TenEyck]

There is metal somewhere above those stains (towards the top of the tree). If you cut off a cookie on the bottom end and the stain still shows on the remaining section of log then the cookie likely is metal free. If you cut off a cookie and there is unstained wood above it then the metal likely is in that cookie. For whatever reason, that black stain travels mostly downward in the tree. Beware, there often is more than just one piece of metal and some metal can be really nasty like electrical insulator lag screws. A chainsaw chain will go through common nails w/o much damage, but it dulls them immediately. Still worth the risk for nice walnut.

John

[Ed Aumiller]

Definitely iron in the wood... Probably nails from either fencing or putting up signs...
Use a metal detector if you have access to one...

[John K Jordan]

Definitely iron in the wood... Probably nails from either fencing or putting up signs...
Use a metal detector if you have access to one...

I agree - I've seen black stains from iron/steel in walnut. Once I found a screwdriver, once a railroad spike, barbed wire fence several times, lots of nails.
I use a Lumber Wizard metal detector at the sawmill. Often there is no indication at the end of the log when the steel is somewhere in the middle. When I find locate the metal I'll sometimes dig it out with a hammer and chisel.

Steel really does a number on bandsaw mill blades. I use extra caution with urban trees, yard trees, and trees from a known fence row (or trees from the middle of the woods where there USED to be a homestead or farm or a hunter).

At least walnut can give you a visual warning either on the end and sometimes if the stain spreads out you might see it when removing a board - some wood gives no hint. I sawed through a 1/2" steel rod in a cedar log once.

JKJ

[Andrew Hughes]

Beautiful looking grain nice and tight. Bummer that you didn’t get a proper long grain slab from the tree.
Those cookies are short on the long grain and mostly end grain that will crack.

[Brian Behrens]

Get some pentacryl to keep those cookies from cracking. It works