Some kind of wood rot.

[Steliz]

Hi,
I was having a rummage through my blank pile for my next 'masterpiece' in wood and I chose a small Oak log. Once I'd rounded it off and dressed the ends I noticed this -

Can someone tell me what it is and whether I should throw it away or make it a design feature!

Cheers

 

[Chrispy]

Sorry I can't help with your question but to pose another, are you sure it's Oak? as as looks more like Ash or Elm on my phone.

 

[Sgian Dubh]

It looks superficially more like a bark inclusion plus a bit of rotted branch than anything else. If that's what it is it's probably from where a branch was broken off a short distance from the main stem and its been covered by the main stem as it grew around it. Even though there is some evidence of historical fungal activity, I presume the wood is dry, i.e., at or below 20% moisture content which means the fungal activity has stopped, and it will remain stopped as long as the wood stays dry.

As to keep or dispose(?) I'd say that's entirely up to you, all depending on your sensibilities and sense of what's 'right' aesthetically. Slainte.

 

[Steliz]

Sorry I can't help with your question but to pose another, are you sure it's Oak? as as looks more like Ash or Elm on my phone.

Hi Chris,

You are right, it's not Oak. I thought I saw the usual medullary rays you see in Oak but it was probably saw marks! Actually, I have plenty of Oak bits so I'm happy that this is something else. I think it is Ash as I made a small side table with Ash and ABW last year and it looks very similar.

Steve

 

[Steliz]

It looks superficially more like a bark inclusion plus a bit of rotted branch than anything else. If that's what it is it's probably from where a branch was broken off a short distance from the main stem and its been covered by the main stem as it grew around it. Even though there is some evidence of historical fungal activity, I presume the wood is dry, i.e., at or below 20% moisture content which means the fungal activity has stopped, and it will remain stopped as long as the wood stays dry.

As to keep or dispose(?) I'd say that's entirely up to you, all depending on your sensibilities and sense of what's 'right' aesthetically. Slainte.

Hi,
The rotten branch theory makes sense for this piece but I have some other pieces from the same log and some of them also have this same condition but it runs right through the heart wood. I don't remember there being any sign of this when I cut it up and the moisture content is below 10%. There is a sketch in my Keith Rowley woodturning book that describes something called 'heart shake' which can be caused by shrinkage although it doesn't mention the discolouration.

Steve

 

[Sgian Dubh]

It's certainly not heart shake because that fault appears as cracks or splits radiating from the pith to the log's/branch's circumference. You could try doing an online search for "heart shake in logs" for examples.

The pith, which you mention in your latest post is at the centre of a tree's trunk: it's the remains of the original stem that developed from the seed, typically around no more than perhaps 15 mm diameter and is usually soft, spongy, and frequently partially rotted compared to the tree's heartwood. In most work, especially finer quality work, like good furniture and high quality joinery, woodworkers remove the pith because it can cause problems in construction such as instability and warping. Others woodworkers, e.g., carvers, turners and the like are more likely to leave the pith in place sort of treating as 'character'. Slainte.

 

[Steliz]

Slight update - despite the low moisture content of the wood the 'rot' is continuing to breakdown the central pith of the main growth as well as the secondary growth off shoots.

I rough turned a piece a couple of weeks ago and had to give up on it due to it being very sensitive to catches which resulted in at least half a dozen design changes to rescue it!. It has sat on my workshop window ledge since then and I noticed recently that the small knot areas were starting to turn black.

I am tempted to chuck it out in case this can somehow spread to my other stock.

Any thoughts?

 

[Sgian Dubh]

Slight update - despite the low moisture content of the wood the 'rot' is continuing to breakdown the central pith of the main growth as well as the secondary growth off shoots.

It has sat on my workshop window ledge since then and I noticed recently that the small knot areas were starting to turn black.

I am tempted to chuck it out in case this can somehow spread to my other stock.

Any thoughts?

The difficulty with trying to assess what's going on is that the piece, or pieces, of wood aren't in front of me to observe changes. Assuming your wood really is dry, i.e., at or below 20% MC then all fungal activity will have ceased, and it won't start again unless the wood gains moisture. It's usually pretty easy to tell if wood is wetter than 20% MC because of the way it works, in this case, for example, how the shavings curl off as you turn it: dry wood produces somewhat dustier shavings that tend to break up and wetter wood tends to produce more continuous shavings that curl off the tool in longer spools. It's not an exact relationship, and shaving characteristics tend to vary somewhat species to species, but there are clues to wood's wetness whether it's turned, carved, planed, sawn, etc.

But, going back to your description off the visual clues doesn't really help me come to a conclusion about the processes occurring. The ongoing blackening of knots may be a something to do with exposure to UV light, or a chemical reaction to something in the air. I suppose it's even possible that some sort of bacterial activity is present, but I really don't know. As to the pith breaking down further as you describe, are you sure it ever had structural integrity to begin with? Pith can be very fragile when it's exposed. Sometimes it's quite woody and hard, at others it's almost like soft dry spongy material, and in other cases it's a mixture of both forms.

As to keep or dispose, again I can't offer definitive advice. If you're really not happy with the stuff, and you have little or no financial or time investment in it either, and it's only a small quantity, perhaps getting rid of it would be best just for your peace of mind. Slainte.