Would like some help drying a piece of blue gum stump

[jimmy1516]

Hi everyone.

I would like some advice about drying a piece of blue gum.
It is a piece of a stump about 120mm thick, about 1200mm in diameter at its widest point.
I am looking to make a table out of it, so it doesn't need to be of structural quality, just hopefully won't warp in the near future.
I have access to precious little equipment or facilities and I am operating on a student's budget.

Thanks for the help.

[Ianab]

Welcome.

This question comes up from time to time, and it's a challenge, especially with wood like Bluegum Eucalyptus.

It's not actually likely to warp, it's going to split, and look like a large pizza with a couple of slices gone. This is because wood shrinks more in circumference than it does in diameter, and most eucalyptus has a large differential. No matter how fancy the drying process, the wood is going to shrink by a specific amount as it dries. Some woods you can get away with this as they shrink less and are more flexible, or the shape of the stump has ingrown bark or a hollow centre that acts as stress relief gaps.

It may be possible to soak the whole stump in a PEG wood stabiliser, which soaks into the wood and displaces the moisture. It stays in place and so the wood never actually shrinks. But that's going to be expensive and isn't 100%.

Other option is, knowing it's going to crack is to actually cut it in 1/2 to make two semi circles. As these dry they should remain intact, but the straight edge will warp. But once dry you can join them back together and fabricate up the missing piece(s) of pizza to fill the gap with similar or contrasting wood.

[jimmy1516]

Welcome.

This question comes up from time to time, and it's a challenge, especially with wood like Bluegum Eucalyptus.

It's not actually likely to warp, it's going to split, and look like a large pizza with a couple of slices gone. This is because wood shrinks more in circumference than it does in diameter, and most eucalyptus has a large differential. No matter how fancy the drying process, the wood is going to shrink by a specific amount as it dries. Some woods you can get away with this as they shrink less and are more flexible, or the shape of the stump has ingrown bark or a hollow centre that acts as stress relief gaps.

It may be possible to soak the whole stump in a PEG wood stabiliser, which soaks into the wood and displaces the moisture. It stays in place and so the wood never actually shrinks. But that's going to be expensive and isn't 100%.

Other option is, knowing it's going to crack is to actually cut it in 1/2 to make two semi circles. As these dry they should remain intact, but the straight edge will warp. But once dry you can join them back together and fabricate up the missing piece(s) of pizza to fill the gap with similar or contrasting wood.

Ok, thanks.

Is there any merit to sealing the exposed sides of the stump (for lack of a better way to phrase it), the little bit of reading I have done suggests that that might help, but I don't know if that would be useful for Bluegum due to my lack of experience.

Thanks so much for the help.

[Ianab]

In this situation, not really.

You seal the end grain because it dries out faster than the sides. This causes the end few inches to start shrinking before the rest of the board or block. By painting the ends with wax you reduce that early drying, the whole piece dries at an even rate, and you reduce end checking.

But this case the piece is still going to eventually dry out the same, and shrink the same in total. It will just take longer.

[Den Socling]

Sorry Jimmy but what Ian should say is "forget it". It's not going to work. You have three impossible obstacles. 1. What we call a "cookie". 2. Blue Gum. 3. Stump.

[JustinW_NZ]

I agree with Den, really bad choice of wood for cookies.

End coating it will make it dry straighter and have less checking but as Ian points out, It will still split eventually.

some old timers I've meet used to slow the process by putting the wood in sawdust piles for a year, but I would say your only delaying the problem..

oversize the cookie, and remove the pith wood from the center with a drill and hole saw, then dry VERY slowly somewhere, this would be your best shot at one piece OR as Ian says just get ahead of it and split it from day 1 and joint it back together later..

photo in my gallery of a customers table where this sort of approach has been done.

Cheers
Justin

[longtime lurker]

Only time I've seen this done with eucalypts with any repeated success was a guy who used to paint tar onto the tops of the freshly cut stumps, then come back years later and cut the cookies out of them. Even then he had cracks after further drying - but fillable cracks not tear itself to bits cracks.

[Den Socling]

I've probably shown these pictures before but I have had some success drying pieces which contained pith if the pieces weren't round like this cherry and walnut.



 



 

[Bill Ragosta]

Not to hijack the original thread or question, but if a cookie is likely to crack, how soon would it typically occur?  I know that it surely depends on species of wood and climate/conditions, but generally does it happen quite quickly?  The reason that I ask is that I've cut 9 cookies out of a fairly large (20" DBH) American chestnut about 2 months ago and at this point in time, none of them have cracked, check or split at all.  Two of those cookies had their end grains treated with Anchorseal and the others were untreated. I haven't tested the moisture in them, but they've clearly and obviously dried a good bit already and I'm hopeful that I may get lucky.

[Denny]

Hey Bill I'm no cookie-expert so I can't answer your question but I'm curious about how thick your cookies are and what physical shape they're in, IE are they perfectly circular or are they oval'ish or do they have an irregular shaped circumference ?

[Bill Ragosta]

I think they're around 10/4" and they're mostly round.  Here's a photo of one of them.....(In looking at the photo, that's actually just a round that we cut off with the chainsaw while in the woods, but the others were done on a bandmill, you get the idea.



 

[Den Socling]

Bill, the irregular shape of the stem in your picture would be a definite advantage IMO.

[Bill Ragosta]

Bill, the irregular shape of the stem in your picture would be a definite advantage IMO.

That's good to hear, unfortunately, only the bottom two or three cookies had those lobes, those on top of that were basically round.  Like I said before, and knock on wood, no cracking yet.