Unidentified stains in black cherry bowl blanks

[Rip Littig]

Has anyone experienced blueish black stains in bowl blanks such as the attached cherry wood photos? My first thought was iron stain but I haven't found metal in the logs I turned into blanks, then cored a few weeks ago.

When picked up from a local landscaper I noticed stains on the end grain face of half the logs (no, I should not have taken those). At the time I shrugged them off as a possible chemical reaction with the chain saw that was surface deep. As you can tell, these stains are on both sides of the large bowl running through the wall. They're also on the small blank pictured and on the other stained blanks I cored. When the wood was very wet it looked like someone drew lines with spray paint.

The tree itself had to be at least 40 years old (22" or larger trunk diameter) so possibly there was interaction with metal long ago. If any of you can share insight I'd really appreciate it. Unique features can be artistically pleasing but I don't find that the case here. I'm hoping the stains fade in the drying process. Thanks again for any helpful thoughts.

 

[hockenbery]

Interesting. I have seen black in cherry from iron and water stains where water sat in a hollow spot like where a limb broke off.
I use lemon juice to remove fingerprint iron stains from touching the wood while turning.
Lemon juice probably won’t remove your stain but worth a try.

Might be an opportunity to use some milk paint or sandblasting.
Al Stirt does a marvelous milk paint bowl demo. Cherry is great for that because it reacts with the milkpaint.

This is a sandcarved cherry piece. A resist is used to mask the image ( feathers here) the background is textured by the sandblasting and painted black with a airbrush for contrast.
You could use various patterns to work the stains into the background a fish bowl can have a random coverage

 

[Leo Van Der Loo]

I have found this only once, but not in Cherry (only brown rot in Cherry) but found this in a White Oak of the neighbours lawn, the tree got removed.

The streak of black/blue ran up the log in the length of the log, I always assumed that there was iron somewhere in the tree, either in the root or base and the iron stain just traveled up the log, just a guess.

 

[Richard Coers]

Cherry is super acidic. Let some wet cherry curls sit on your lathe bed for some time and you will see what the reaction is. (Don't really do this, your bed lathe will have rust pits in just a couple days.) Steel chemical stains can travel many feet away from the steel.

 

[Brian Gustin]

Almost wonder if there are examples someone may have of trees that survive a forest fire and keep growing, if there may be some signs within the tree growth rings of that long-ago forest fire? I have had that happen several times with some of my cherry bowls (as well as that green-ish stain between heartwood and sapwood) and have been mystified a number of times. At first I assumed it was just steel particles in the gouge from grinding it , but I also experienced those stains show up (they were not there initially) while roughing out a blank with a carbide scraper tool (no steel anywhere near it) - my second theory was some kind of oxidization of mineral content that was already there (that perhaps the tree drew up from the ground, or maybe it grew near a roadside, or any number of other things?) But I have no ideas as to that greenish looking stain that I have seen in some cherry that just seems to separate the heartwood from sapwood...

 

[robo hippy]

Look like iron stains to me, and not from your hands like metal powder from when you grind. The metal streaks can travel a long way up the tree, and only a little way down the tree. I have seen dark mineral stains in some woods, but most of the time black means metal, some where...

robo hippy