grizzly1 - Posted - 12/07/2009:  16:01:07

First of all, Thanks everyone for all the great discussions. I have learned a huge amount just listening. This is my first posting as I just recently got the nerve to join, so please bear with me.

I have been gathering a selection of woods to start seasoning in preparation for building my first complete banjo (or banjos). A couple of weeks ago I ran across some decent colored Gabon Ebony at a favorite wood supplier. Remembering the recent posts and pics on the thread that Ol Lefty started on ebony banjo building, I figured I would get some to throw in the pile so that maybe in a few years it might be ready.

My first clue should have been that the entire chunk had been dipped in paraffin. Figuring that the moisture needed some place to go for the wood to equalize, I got out my scraper and took off most, but not all, of the wax from the side surfaces. The ends were left covered. It was beautiful in grain orientation, color, free of checking and yes, a little on the damp side. At this point a family member had some health problems, so I hopped a plane and was gone for a couple of weeks.

When I returned, to my horror, the ebony had basically exploded. The biggest billet cracked all the way through the two inches of thickness about 2/3s of the way down the board. Most of the surfaces are now covered with micro/macro checking. In retrospect I am guessing the piece must have come straight out of the tree, past the resaw, and into the paraffin pot.

My attempts at recovery were as follows: I got out a large bottle of cyanoacrylate and tried to stabilize the smaller checks until the fumes were so bad the wife and the huskies were driven to the other end of the house. In retrospect I am not sure this was a good idea. The core problem, as I understand it, is that despite the waxed ends the outer surface is drying faster than the middle and the outer surface is shrinking around a still expanded (waterlogged) core. I am now wondering if supergluing the smaller checking will just transfer the stress to adjacent areas and create more checks.

To try to get at the underlying moisture discontinuity, I took a suggestion I found online at one of the woodworking sites: " Two hours at 200 degrees in the oven will drive the moisture out of Spruce and Ebony". Well, it may well have "driven" more moisture out, but it also drove more checking in. The whole mess is now tightly wrapped in a plastic bag, to try to slow the drying process, and because I can't bear to look at it.

So: Any suggestion for a newby as how to safely dry really really green ebony. In two weeks this wood went from a fine but green billet, to something that looked like a firecracker went off in the middle, despite waxed ends.

Thanks,

Mark

Helix - Posted - 12/07/2009:  16:22:41

Hi Mark, what a great thread, welcome to the forum.

You are right about the moisture barrier. I once bought some Black Walnut that had internal cavities not visible from the surface, the planks were already planed, I thought that to be good, but the wood had been improperly cured.

Cap the ends with paint or wax. Your piece must have been green green. It may be difficult to rescue this particular piece.

Best of luck

Edited by - Helix on 12/07/2009 18:26:31

Brian T - Posted - 12/07/2009:  16:30:11

Hey Grizz, welcome. Could be why the whole piece was waxed. Woodworker pal had an end table explode in a spare bedroom one winter night. He resawed some billets to 1/2" and edge glued them, knew they were "damp."

As water molecules escape from the wood, the residual tension can reach 1,000psi or more. I just wrecked a 8" x 24" piece of alder at the rough-in stage of a carved bowl. Left it for 2 weeks, 1/2" split the whole length. Quite impressive but I wasn't in love with it anyway.

How to do it safely? Time. More time. Probably more time than you have.

grizzly1 - Posted - 12/07/2009:  17:40:22

It occurs to me that what I need is a semi-permeable membrane. I wonder what sort of coating would do? something that's not waterproof. Tung oil? Paraffin is too resistant to moisture transfer, and obviously the scraped surface is loosing moisture too quickly.

or is the way to go finding someone who does kiln drying?

Thanks for the thoughts guys,

Mark

rudy - Posted - 12/07/2009:  17:52:45

Grizz,
I'm wondering if the billet you obtained was center cut from the log?
Ebony continues to be harvested from smaller and smaller tree sections, and the tighter the grain toward the center the less stability can be expected from the resultant dimensioned lumber obtained from it. This may be a case of your purchase, amounting to harvesting and marketing an unusable portion of the tree. There's a reason why good, stable, and useable large pieces of ebony are priced the way they are.

grizzly1 - Posted - 12/07/2009:  18:14:37

Thanks Rudy,

I am not sure I can tell how close the rings are. It somewhat obscured by the wax, which is mostly melted in/away by the ill fated home oven/kiln-drying experiment. The grain I think I can see is oriented vertically and does not have much of a radius to it. This brings up an interesting point for me. How does one know when faced with waxed ends what you are dealing with: you don't. When I was at the store i did scrape a little off one end, but couldn't tell much from the exercise.

again, thanks,

Mark

RBuddy - Posted - 12/07/2009:  18:59:44

I'm bettin' Randy (Rudy) nailed it. Could even be a squared up limb.

Brian T - Posted - 12/07/2009:  20:40:54

Possibly, Grizz bought a limb or a leaning stem that was 1/2 tension wood? Rudy's offering suggests some microscopic detective work.
I can do that with my handy-dandy Nikon 'scope and a wood-cutting sledge-microtome that I can get access to. Ah, the smell of boiled ebony.
Grizz, you're not that far away. Maybe to rake the wax with a comb might allow more gas exchange but I'd go no further.

Pine Cone - Posted - 12/07/2009:  23:33:05

What about soaking it in polyethylene glycol? Should rehydrate it and might stabilize it?

http://www.rockler.com/product.cfm?page=686