highly corrosive green wood? Red Oak

[Melvin Feng]

neither am I a metalurgist, and perhaps I am using the terms incorrectly.

I only meant to imply that the staining is a cosmetic nuisance but doesn't corrode it to the point of compromising the functionality.

Ah! I see. Yes, there is only a stain left on the ways now, no rust that I can see. It was a bit worrisome. The chuck jaws though definitely look to have some pitting, so I'll need to be much more aware of these things when I am turning green wood in the future!

[Dave Mount]

The black color is from the interaction of iron with tannin's in the oak. Although it looks bad, the amount of iron lost to it is infinitesimal. Some people actually use this reaction to "weather" (think barnwood) oak and some other woods by dissolving some steel wool in vinegar then painting the solution onto the wood. The acidity is probably important to dissolving and keeping the iron in solution, as iron (Fe^3+) is not very soluble at higher pH.

I spent a period making green-bent chairs out of oak, and the thin back splats were bent into the chairs green. I'd rive the back splats out of green quartersawn (er. . .quarter split) oak then hand plane them to final thickness. I had to use a wood bodied jack plane for this, because iron-bodied planes would turn the whole thing grey (wet wood). Oxalic acid can be used to bleach the grey out if need be.

As far is actual pitting tools/lathe beds, I don't think (from my own observations, not science) oak is substantially worse than other woods with high moisture content -- any of those will get rust going if you leave them on unprotected surfaces. Oak just looks worse because of the grey/black color.

Beyond wiping down the ways of the lathe, one place it's easy to forget is the shaft of the tool rest and the hole in the banjo. Learned the hard way that when turning wood that is actively throwing water, it can seep down in there and cause a mess. Now after turning green wood I always remove the tool rest and wipe it down, then spray compressed air down the hole in the banjo.

Best,

Dave

[Reed Gray]

I am wondering about the lathe tools getting pitted. Never happened to me. I do get some coloration on the sludge that builds up on the tools, but nothing that actually discolors the metals. I turn pretty much only with Thompson and D Way tools.

robo hippy

[Peter Blair]

This is exactly why I don't turn green Oak. Was a bad experience for me and not worth the effort!

[Scott T Smith]

The black color is from the interaction of iron with tannin's in the oak. Although it looks bad, the amount of iron lost to it is infinitesimal. Some people actually use this reaction to "weather" (think barnwood) oak and some other woods by dissolving some steel wool in vinegar then painting the solution onto the wood. The acidity is probably important to dissolving and keeping the iron in solution, as iron (Fe^3+) is not very soluble at higher pH.

I spent a period making green-bent chairs out of oak, and the thin back splats were bent into the chairs green. I'd rive the back splats out of green quartersawn (er. . .quarter split) oak then hand plane them to final thickness. I had to use a wood bodied jack plane for this, because iron-bodied planes would turn the whole thing grey (wet wood). Oxalic acid can be used to bleach the grey out if need be.

As far is actual pitting tools/lathe beds, I don't think (from my own observations, not science) oak is substantially worse than other woods with high moisture content -- any of those will get rust going if you leave them on unprotected surfaces. Oak just looks worse because of the grey/black color.

Beyond wiping down the ways of the lathe, one place it's easy to forget is the shaft of the tool rest and the hole in the banjo. Learned the hard way that when turning wood that is actively throwing water, it can seep down in there and cause a mess. Now after turning green wood I always remove the tool rest and wipe it down, then spray compressed air down the hole in the banjo.

Best,

Dave

Excellent explanation Dave.

[Brice Rogers]

If I'm turning wet oak, I put a sheet of plastic over the ways and then dump it and air-spray the bed when finished turning. Pre-applying WD40 or Boshield, etc. to the ways before covering them also is a good idea.

Also, I will sometimes put some stretch wrap or saran wrap over the chuck jaws, especially if I'm going to leave the piece chucked up for a few days. The reason for that is that it keeps the chuck jaws from leaving a black stain on the tenon or mortise - - plus also keeps the jaws from turning black.

[Melvin Feng]

Those are some good tips. I did apply some CRC 3-36 before turning, but I still had staining issues. The saran wrap would have definitely helped the jaws though, there is some pitting, and it left the black stain on the tenon as well.