# What would cause blue-green streaks in wood?



## Nickkwins (Aug 14, 2016)

I was planing some hackberry boards and I noticed a blueish green tint in the grain pattern that wasn't visible until planed. It looks kind of cool but since I'm making these into cutting boards I want to make sure that whatever caused this coloration is safe to contact food. So can anyone tell me what caused this and is it safe to make a cutting board out of this?


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## gfadvm (Jan 13, 2011)

Harmless wood fungus. Beautiful!


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## DirtyMike (Dec 6, 2015)

Makes me wish I was a worker of thy wood in the past. I cant count how many 80' hackberrys and locust i have cut down on my parents property. great looking wood.


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## TheFridge (May 1, 2014)

I made a table and chairs out of spalted hackberry elm. Great stuff and awesome color


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## wormil (Nov 19, 2011)

If it was standing dead tree or on the ground then probably fungus. But the fungus has to get that deep inside a tree somehow and typically it's through bug holes or if the tree was cut and left on the ground then it can enter through end grain. If you believe it's spalting and the wood hasn't been kiln dried then I would kill the fungus with heat because it can continue to spread. If it was a standing live tree then probably a mineral stain.


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## Tabletop (May 9, 2016)

I don't know if it is 100% accurate but, the old folks around here say that there would be metal in the tree. Probably an old fence or nail.


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## WDHLT15 (Aug 15, 2011)

That hackberry has a lot of gray stain. It is a chemical reaction, an enzymatic oxidation reaction of the sugars in the wood when the temp and humidity is high. It is seen in a number of light colored woods like maple. It happens when a log lays for a long time before being sawn or when lumber is sawn and stacked to dry where there is no air flow to wick the moisture away as the water evaporates from the boards.

I believe the green color to be a reaction similar to the gray stain reaction. So, I believe that it is a chemical and not a fungal infection.

"Some other hardwoods develop a similar discoloration during drying. Sugar hackberry (Celtis laevigata wild.) sapwood lumber often develops a brownish-gray to greenish-gray discoloration just below the surface 
and sometimes through-out the cross section of the piece. This discoloration is difficult to control because 
the discoloration can develop within two to three hours after sawing during warm, humid weather."

Quote above from this research study:

https://wfs.swst.org/index.php/wfs/article/viewFile/1013/1013


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## wormil (Nov 19, 2011)

> https://wfs.swst.org/index.php/wfs/article/viewFile/1013/1013
> 
> - WDHLT15


Good read, thanks.


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