Thread: Australian timbers and tool steels

Originally Posted by Luke Maddux

"...and whether or not it has the hardest woods to work, Australia has, in my opinion, the best," he said, glancing nervously about in anticipation of incoming backhands or sticks made of Hickory.

Cheers

Derek

Also, Stewie, to say that a soil contains ore is a misuse of terminology. Ore is any rock from which a mineral is extracted by humans. It's not really an ore until we want to go get it, in a sense. If humans ceased to inhabit the Earth, then "ore" would cease to exist, and if there were bits of a rock type which could be an ore (like Bauxite) in a laterite soil, it wouldn't matter because the minerals would be bound up in the rock structure and not readily accessible by the tree.

I'm not sure if that was even remotely helpful to the discussion... but I think it's an interesting one. I also don't think it's a witch hunt, and I'm glad you brought it up, Derek. Whether we find an answer to the question or not, the whole point of this website is for a bunch of dudes to chat about wood, so: Mission Accomplished.

Luke; you will have to excuse my excuse my misuse of the terminology "ore". I am not a Geologist. Understanding the science of why 1 timber is harder than the other is not something I get overly concerned with. No doubt a result of my blue collar background.

ps. In Australia we dont call ourselves dudes. That's Yank terminology.

Stewie;

I've managed to cool down a bit and am feeling somewhat less dehydrated.

This figure is abstracted from Wikipedia:

Elemental abundance in crust 062317a.jpg

This figure shows the abundances of the more common elements vs. their atomic numbers that are present in the crust of the Earth. The top five elements are oxygen, silicon, aluminum, iron and calcium in decreasing order of abundance (red highlights).
Oxygen is ranked first primarily because the following four elements occur as various compounds with oxygen and silicon (No profit or point in discussion of nucleogenesis here.). Silicon constitutes approximately 28% of the mass of the crust. Silicon occurs mostly in the form of silicates (SiO₄)^4- of other elements. The other major naturally occurring form is the dioxide (sand or silica).
As Luke has pointed out, silica depleted does not mean silica free.

From my readings of the papers I mentioned above it appears that silica/silicates inhibit the destruction of wood and plants generally by herbivores, apparently by abrading the body parts that they use to eat the wood.

I've been following this thread with interest. There have been some great contributions. I had a look through the links that BobL posted earlier and one in particular on the mineral content of NSW trees is interesting in that they compared the mineral content of the bark, sapwood and heartwood and found huge variation within a tree. They also compared the same species from different districts and compared variations. There is also reference to a 1952 study by Amos of the silica content of 400 species. This is available in book form from Australian libraries.
http://www.dpi.nsw.gov.au/__data/ass...ee-Species.pdf

That got got me thinking about other properties of trees which led me to this book excerpt from The Preservation of Timber in the Tropics:
https://books.google.com.au/books?id...silica&f=false
Here it states that silica content is more important than physical properties of wood in attack by marine borers but Jarrah is also resistant due to the presence of alkaloids. So the idea that other minerals may be present to affect workability is not unreasonable.

It also compares the Silica content of Turpentine grown in Australia (0.59%) having high marine durability to grown in Hawaii (0.09%) and being susceptible to attack!

So where the wood grows definitely matters.

It also compares the Silica content of Turpentine grown in Australia (0.59%) having high marine durability to grown in Hawaii (0.09%) and being susceptible to attack!

Our Turpentine is resistance to attacks by sharks?

So where the wood grows definitely matters.

That appears to be a logical conclusion to which we are coming. Is there something different about the regions in which our timbers grow, and compared to other countries. One possible distinction is climate: the fairly dry and hot WA (at times desert) conditions versus the wetter climes of the Eastern states.

I wonder if eucalypts grown in the USA (where they were transplanted from Oz) work the same way as here? (Assuming that anyone has managed to harvest them for timber - from what I have read, these trees, although now abundant, are considered likely to check and split too much when drying to be worth the effort).

Regards from Perth

Derek

Judging by this article, the South Africans might be a better source of that detail as Australian Eucalypts and Acacias are grown for comercial timber and honey industry.
https://www.ssrc.org/pages/A-Contest...-South-Africa/

A little more botanical information here from the CSIRO. Dates to the 1970s. Tables at the end.

https://publications.csiro.au/rpr/do...979c5&dsid=DS1

Regards
Paul

Interesting thread, surprised I hadn't noticed it before

Originally Posted by IanW

..When it comes to Bull oak, or Buloke (Allocasaurina leuhmanii)...it's far better to work than many other of our famously hard woods... it's easier to work than Gidgee...

Now this raises an old argument of mine, that Buloke is not the hardest timber, just the samples or Janka tests were flawed???? I have worked a fair bit, never found it really that hard and it worked well (turning anyway), and indeed I have had some samples I can mark with my fingernail . Perhaps the samples tested were affected by fire or lightning making it harder than normal??

From my own experience the hardest timbers are a close race between Minirichie (Acacia grasbyi), Inland Rosewood (Acacia rhodoxylon) and Waddy-wood (Acacia peuce), especially old samples (100 year old posts/beams for example) that apart from the silica obviously have the odd bit of sand and grit in them. The age affects timbers too, case hardening of some sort, I know if you mill Bluegum for example it is relatively soft (for a euc anyway) if you mill it within days of dropping it, but leave it for a month and it is as hard as leaving it for 10 years. Inland Rosewood turns almost to steel when aged.

Which brings up another impact affect on hardness/workability, fire/lightning/desert conditions/age etc.

Neil

You raise an interesting aspect and it is one of availability. If you live in Sydney or Melbourne and never travel more than 25Km from the centre you are probably severely restricted in what is available from your local timber supplier. These timbers become the so-called commercial timbers as they are available in relative abundance.

Once you start to travel, as I know you do, you discover a whole new world and exotic doesn't begin to describe it. The fact is that the timbers you are familiar with, the vast majority of people have not even heard of let alone worked with. They are certainly not commercial (the timbers, not the people) as if you find these timbers, you might be lucky to half fill your ute with them: Certainly there is no way you are getting a jinker load!

Hairy Oak and Bull Oak are two of my favourite timbers for knife handles: To my mind they are almost, but not quite, unsurpassed by any other timber, but I am still trying to find a billet to successfully recover a sound blank large enough to make a saw handle.

IanW grabbed a ute load of this material and said he only found about five pieces large enough and sound enough to make small saw handles.

Some of the Acacias are the hardest woods you can imagine and the most dense, and I love them, but they are probably not typical of Australian timbers. Having said all that (probably had too much to drink: Anybody here like Harvey Wallbangers?) Australian timbers are in the aggregate harder than those from Europe and North America, but not necessarily all other countries . Just to bring the subject back on topic, the question was does the hardness of these timbers make them difficult to work and does it dull the cutting edges of both hand and machine tools prematurely?

Something to ponder is the length of cells or pores of the timber. Hardwood is sometimes botanically better described as pored wood (and softwood as non-pored wood) but the length of the cells varies. Perhaps the length has some effect on "pick up" for example. Similarly something within the structure is having an adverse effect on edge retention: Possibly a combination of several factors: As my boss says, "when all the holes in the cheese line up......."

Cheers
Paul

Originally Posted by dai sensei

..... Now this raises an old argument of mine, that Buloke is not the hardest timber, just the samples or Janka tests were flawed???? I have worked a fair bit, never found it really that hard and it worked well (turning anyway), and indeed I have had some samples I can mark with my fingernail . Perhaps the samples tested were affected by fire or lightning making it harder than normal??.......

Neill, the 'flaw' in the tests might be a small number of samples, & possibly from a single area. This business of "fire-hardening" often comes up, and according to at least two books on wood technology, it's a bit of a myth. What's giving the impression is that all woods become harder as they dry. If you 'dry' a bit of wood over the fire, or by holding it up to a few lightning-strikes, to make your spear-point, it's going to be much harder than what you started with if it was a green stick. It may be harder than naturally dried wood if you manage to get it to zero MC, but only until it equilibrates with whatever the local air MC dictates.

I grew up with other stories about wood & heat, like lightning-struck trees are no good for fence-posts because they rot twice as fast. Perhaps there is some truth in that, you could hypothesise that the sudden, massive heating that boils the water in the tree & causes them to explode, opens up millions of minute cracks in the wood that looks sound, allowing more easy ingress of water. However, when I was about 16, a large stringybark tree on a ridge copped a strike that literally split it into fencepost-sized billets, right where we were building a fence. I thought it was a gift from heaven - all we had to do was cut them to length. The normal life-expectancy of that species in that location is about 70 years. The fence was still sound last year, so that gives them 55 years & counting. They might make it to the average age, barring a major fire or or other catastrophe. In any case, we got good buck for the bang, I reckon...

Of course the flaw in that anecdote is that it was one tree, one lightning bolt & one fence-line...

Originally Posted by dai sensei

..... From my own experience the hardest timbers are a close race between Minirichie (Acacia grasbyi), Inland Rosewood (Acacia rhodoxylon) and Waddy-wood (Acacia peuce), especially old samples (100 year old posts/beams for example) that apart from the silica obviously have the odd bit of sand and grit in them. The age affects timbers too, case hardening of some sort, I know if you mill Bluegum for example it is relatively soft (for a euc anyway) if you mill it within days of dropping it, but leave it for a month and it is as hard as leaving it for 10 years. Inland Rosewood turns almost to steel when aged.

I reckon Western Myall (A. pendula) could take its place somewhere in your list too. But Lordy, you've got me worried, now. I have a couple of half-logs of A. rhodoxylon under the house from the stash that Luke acquired not long before he left. Might be like some poor wines - better laid down & avoided forever! Still, I managed to turn a walking-stick from an old A. rhodoxylon fencepost for a friend about 10 years ago. I wasn't sure what it was at the time, & it was only a little while ago when I compared a scrap with some known A. rhodoxylon that I figured out that's what it was. Apart from density, colour & texture, the 'bouquet' is the clincher (there was still quite a distinct aroma, even after 50 or 60 years of life as a post!). I remember it as being up there with the hardest woods I've turned, but it was mangeable, and certainly took a magnificent finish. Maybe I'll use the new stuff for Babbet bearings or something like that.

Haven't tried planing any of it yet - if you see a blue cloud over Pullenvale way, it might be the day........

Cheers.

Yikes, Neil... From what I can tell you've put steel to about as many Aussie woods as anyone who regularly visits these forums, so for you to say that about the Inland Rosewood definitely gives me pause. As of now I don't have a dedicated plan for it, but I'll make sure it involves electrons.

Come to think of it, I exchanged some emails with Vern from TTIT few months before leaving, and he said something similar.

I'd say there's a solid chance that if anyone has ever done a Janka test on it then the data is long since forgotten. Maybe someone needs to buy a hydraulic press and get to work!

Luke

Bootle mentions Acacia rhodoxylon, but only briefly pointing out it is confined to central and southern regions of Queensland. It is, as we might expect, very hard and dense with an ADD of 1280kg/m3. It was supposed to be very strong (S1/SD1). That is the limit of the information.

However, it was not listed under Inland Rosewood, but Spear Wattle. As we know there are many local names for timber and some timbers have a multitude of names (Dead Finish and Black Wattle immediately spring to mind). However the "Spear" aspect I thought was rather significant and probably indicative of it's nature.

Regards
Paul

Originally Posted by Luke Maddux

Aluminium is an element. It exists at the atomic level and binds readily and frequently with silica in nature. Definitely not man made.

Originally Posted by Luke Maddux

I'm not being condescending, so I hope it doesn't come off that way.

Cheers,
Luke

+1

I also don't wish to sound condescending, but yes it was made, probably in a collapsing star at some stage in the formation of the universe.

But, it is so reactive that it rarely occurs in isolation.

Wiki quote:

Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal. By mass, aluminium makes up about 8% of the Earth's crust; it is the third most abundant element after oxygen and silicon and the most abundant metal in the crust, though it is less common in the mantle below. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals.^[7] The chief ore of aluminium is bauxite.

I'm thinking along the same lines as Bodhan, that aluminium oxide could be as much the culprit as Silica. Does it occur naturally in wood?

re aluminium salts.
perhaps more fruitful would be an exploration of the solubility of the various naturally occuring Al salts, and for that matter Iron (Fe) salts, especially compared to silicon salts.

For Stewie, one reason you get laterite and Bauxite deposits is that the relevant Fe and AL salts are not very soluble and hence they get left behind as the other salts are disolved and washed out of the soil strata.