got a good question

[Mike_Barcaskey]

talked with a sawyer today, tramp metal came up and how to detect it
staining in the wood was most of our conversation

let's say you have a nail in a tree
he claims in some species, the staining will be above and below the nail in the wood
and in other species the staining will be only below the nail

I'm of the opinion that the staining will appear above and below
because the sap runs both ways

what do you know?
no opinions not based on fact please

[Frank_Pender]

All of the species I deal with the stain goes primarely down the tree.  There is, at times very minor stain above the metal entry, like two or three inches. :'(

[woodmills1]

in oak the stain is very noticable below the tramp most times all the way to the end of the log.  sometimes you can see stain on the pass just before you get to the metal.  drywall screws don't stain much but being hardened they ruin blades.

[Ron Wenrich]

Galvanized or coated steel will not show any stain.  I hit a 3/8"x1"x8" piece of galvainzed steel in a log.  It didn't show stain within 1/2".  Wiped out a big blade.

Most times the blue will go mainly down, with a little going above.  It depends on the amount of steel and how long its been in the log.  Sap flow has little to do with it.  Probably has more to do with osmosis and gravity.

[Mike_Barcaskey]

sawed a piece of black oak up today for firewood, a little too knoby and curved for the mill

found a nail and the staining was about 13 - 18" both ways
this is what sparked this thread

(brain fart - the sawyer conversation was a couple days ago, dont know what I was thinking when I type the first post and said it was today)

[SwampDonkey]

If it's a regular nail, I'de say the stain can travel both ways. In the xylem, which is the wood , minerals and water travel up the tree so the stain would travel upward. In the sapwood of the xylem, the direction of flow can be bi-directional, because food is stored here and can be transported where needed, and the stain can be up or down. But, would mainly be downward because food produced in the crown comes down the phloem (inner bark) to support wood growth , root growth and maintenance.