What is the black stuff?

[Brian Grenia]

Walnut bowl. What is all the black stuff creeping into the sap wood? Could I have avoided it?

 

[John Jordan]

That is fungal growth, supported by the free water/sap. If you had used compressed air to blow the free water out after you turned it (before sanding would be best) it would stay white. Not much you can do now, and lemon juice won't remove it, though that is often suggested. Lemon juice removes the black stain from tannic acid/iron.

John

 

[Keith Barrett]

I'm not familiar with using compressed air to dry a freshly turned vessel...please elaborate. Thanks.

 

[MichaelMouse]

At what point in the process did it start showing up? You can keep sapwood brightest by getting into the log quickly. Any length of time with the bark on will allow the fungal growth to begin as long as there's sufficient temperature and moisture. Got to deny at least one.

Shakeout can be as simple as spinning the fresh rough rapidly - after ensuring it's secure - say 1000-1500. Let the water fling until it stops, wait ten minutes, repeat. You can also use compressed air along the grain - won't do much trying to push sideways. Air ejection more of a tactic for thin-cut stuff which will warp freely. If the bottom is broad and thick, you'll have very little luck pushing water out.

Other things include no bagging with wet shavings. Better no bagging at all, but broader bottoms might not be able to take more rapid open air drying. Dry shavings will pull moisture somewhere in between open and green, but should be discarded and replaced after two-three days and then a week.

Last, cut your blanks so you can store them out in the garage while temps are low. Growth is retarded/halted below the fifties. No bagging required, because the cooler temps will normally provide higher RH than indoor air.

Lemon juice is for your skin. Handy for the iron tannates wood can create.

 

[john lucas]

Keith There isn't much to elaborate about. Just turn on the compressor and blow. After John showed us this technique I tried it. There's really not much learning curve. You just aim the air and it only takes a short time to figure out which direction to aim to get bubbles or even spray coming out of the wood. I only do it on the sap wood area since that's where the fungus discoloration is a problem.
This works best when the wood is fresh cut and hasn't been sitting long. The longer it sits the more discoloration gets into the sap wood that won't come out.

 

[Brian Grenia]

To date, my process was to rough turn, anchorseal and store, then finish in yr2 (this is when I discovered the fungus)

So to clarify....

1) I should rough turn, spin and blow, then store. I should avoid the anchorseal I imagine? b/c it adds/traps moisture??

2) There is no need for comp air on the final turning before sanding b/c the wood is dry by that point. Right? Wrong?

I'm a little concerned about the bowls cracking without the sealer.

Thanks

 

[MichaelMouse]

Yep, rough, then try to eject as much water as you can. Spin keeps it moving in one direction - outward. While you can blast from inside ONLY on the endgrain, won't do you a lot of good, because that's what dries fastest anyway. If you have a long area of grain like a broad bottom or thick sides, I'd just spin.

Anchorseal is a tossup. The thing you worry about is relative humidity. If you take care of that by placement in your storage area, you won't need to enclose in wax or bags. If your only choice are dry areas, might want to go with one control - bag/box/wax your choice. As I said above, broad bottoms mean a long way from the inside to escape. it's differences between surface and interior that causes trouble. On my stuff there's rarely any place on a rough that's more than an inch and a half or an inch and three quarters from escape, so I don't worry.

Once the piece has reached equilibrium, you don't need to eject unbound water - there isn't any. Nor more than maybe half of the bound water. Doesn't hurt to give a shot of air between grits of paper, though.

 

[Brian Grenia]

Ok next issue.

I drug the compressor in to my SMALL shop. It is a Bostitch pancake compressor that I bought to run my nail guns years ago.

It is louder than war.

Are there small silent (or close to silent) compressors that anyone would recommend or do I just have to put this thing in a closet and run the hose through the wall/ceiling.

As of right now, not running any tools off of air.

Thanks

 

[MichaelMouse]

For as little as you use it, ear defenders will certainly do. Or you may do the long hose routine. My compressor has fifty feet permanently mounted so it'll reach the garage. It's also a piston type now. Those universal motors are noisy enough, and used with diaphragm design, just too jarring.