# Wood "hardness" simple tests (pic heavy...!)



## robutacion (Sep 2, 2014)

Hi peoples,

Everyone knows that, wood hardness is something that we, woodworkers, turners, etc., deal with on a daily basis, sometimes its turns out to be a lot more than just, "wood is a bit soft...!", how soft is it...??? its softness is a lot more important than its hardness, in most cases, particularly for pen turners where, attempting to handle a blank with soft patches or a blank that is all very soft, without any sort of hardening or preparation, can turn into a nightmare and more often that not, a fail...!

In our days, where home wood stabilization is no longer a problem, I wonder what people use to determine if the blank is too soft to attempt to turn, totally raw. Sure, thin CA saturation can be as effective as stabilization, probably a little more expensive, a little less effective in bigger wood dimensions and certainly, a lot more dangerous to ones health (fumes).

Does one need a specific "Durometer" (hardness gauge)...??? sure not, particularly when until recently, those instruments were extremely expensive...??? 

Have you have asked a "gadgets" person, if he or she wouldn't consider every possibility to own them, even if they are never used or used a couple of times...??? well, I can tell you what the response/answer would be, as I'm one of those...!:wink:

If there is something that I really like about todays technology, is the fact that, made in China or thereabouts, allows you to own gadgets that you never thought possible, a decade or two, ago.:wink::biggrin:
With this in mind, I come across an instrument on eBay that got my attention, first for what it was made to do and secondly, the very affordable price of under $50.00 shipped, such as this one (this was not from where I order mine but is the same thing and has more details about the items than the sire I got it from, a little cheaper too...!)

There are 3 types, A, C and D, I didn't realise that until I got mine and searched a little more, as I didn't like the tip and the softness of the spring.  I then found out that, I should have got the "D" type, as shown below.




I decided to pull it appart and make a few modifications, one was to sharpen the probe end into a point and second was to, replace the spring with a much stronger one.  

I have never used these gauges before but, I'm certain that I made it very similar to the "D" type and therefore a lot more suitable for the intended purpose...!
The final adjustment was made on the screw at the top of the instrument and under the top "T" knob, screwing it in or out, I manage to get the low readings on the soft wood as I wanted and at the same time, have better readings on the harder woods.  I doubt that the "official calibration" of the instrument is off however, I don't know that for sure and it doesn't really matter to me...!

OK so, with the gauge reading the way I wanted, I started to do some testings and see what would happen/say.  Next are some pics of the instrument after modified and a test that I done to confirm if I could still read the 100% the unit was made for, I used the metal bandsaw table and the results are very close, at 94% so that is the hardest it will read, on totally solid steel, wood has to read lower than that...!

 
 


After I got the maximum reading calibrated, I decided to make some readings on materials that we all recognize as soft, and everything in between.  My benchmark was to see what the readings would be with some true Cork (bark), not the softest but surely one that we are all familiar with...! 

 

I have only one other wood/plant type material, that is softer than the Coral tree,  View attachment 121570 View attachment 121571 and that is the "Century Plant", that I cut from this area a few years ago, not the one is the pic below (I got this on Google) but mine was a lot bigger, I got 7 pieces of my height (approx 170cm/67") that made it about 12 meters tall...!



This material has the same consistency and weight to the Polystyrene even though at the time, and before I got my stabilization gear, I made pen blanks and pens out of it however, I done a lot more work with this material, after I started stabilizing...!

 

My hardest wood, is the #66 Australian Swamp Mallet Gum, that I have growing in the area, as the name indicates, this is a tough wood when properly dried.



Next, is a series of pics of different of my woods tested for hardness and compared with its weight, against the hardest and heaviest woods and to the softest and lightest woods.  My apologies if the digital numbers are a little difficult to read on some samples, was the position I had to put the camera to avoid the flash blindness/witness that caused it, the instrument shown the digits very clearly and vividly...!

 
View attachment 121590 View attachment 121591
 
 
 
 
 
 
 


Often, the question is asked, how hard does a wood become after stabilized...??? 
I decided to show you this example of something that is not really wood, is 100% buoyant like cork, is not the best soaking materials, (by the contrary) however, it shows a considerable/significant hardness difference between raw and stabilized, and this is the Pine bark...!

 

One other common question is also, why do I have so much trouble with blanks that are made with a combination of wood(other) and resin (polyester but not only), they keep exploding on me..???

Well, one of the biggest culprits is, the hardness difference in between the materials used in that blank. Even when these blanks are made with wood and resin, various things should be considered, not all woods have the same hardness and not all acrylics/resins have the same hardness, also.

So, why do they blow appart...??? simply look at the 2 pics below, the wood used in that Resifill (cast) blank is my #22 Olive root, a very medium to soft wood, compared with the readings you see on the resin patch on that same blank so, and unless your tools are very sharp, you have the right cutting techniques or use the flap disc, any minimal catch from the transaction of the softer to the hardest material, will result in a bad chip, some separation or the blanks disintegrates in front of you and that, is not the blanks fault...!

 

And to wrap up this hardness tests thread, I will leave you with 2 interesting pics of the "famous" #45 Banksia Hairy pods Resifills pen blanks, where I tested the hardness of the Banksia Hairy pod "eye", that has been stabilized and then cast, the blanks was sanded so there is no resin over that part of the pod, it is solid from the stabilization and shows no hardness difference, from what the blanks has at the middle point where, the hairs joint from the 2 pod halves, there is mostly resin (polyester)...!

 

What am I trying to say...???

Well, make your own judgment...!:wink::biggrin:

Cheers
George


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## thewishman (Sep 2, 2014)

Fascinating! Thanks for the thorough explanation and all of the pictures. That had to be a lot of extra work - and it adds so much to understanding your process.


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## wood-of-1kind (Sep 2, 2014)

Hi George,

I have a DUROMETER made by PTC Instruments. Very useful but very "delicate" too.
Needs to be calibrated occasionally so I am intrigued at the fact that you are able to make "adjustments" to your unit and still maintain it in good working order. Well done.


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## 1080Wayne (Sep 2, 2014)

Now I need another toy !


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## flyitfast (Sep 2, 2014)

Is this that "one more tool" I need for greatness?????
gordon


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## robutacion (Sep 3, 2014)

flyitfast said:


> Is this that "one more tool" I need for greatness?????
> gordon



I doubt mate, "greatness" come from many other places, not tools and gadgets...!

Despite the fact that, I'm totally OK when people call these "toys", some do have actually some good use, this one gives me a more accurate hardness info than the common, fingernail push-down or others so, any money that is spent for anything other than, doctors and medicine, is a better way...!

Cheers
George


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## robutacion (Sep 3, 2014)

wood-of-1kind said:


> Hi George,
> 
> I have a DUROMETER made by PTC Instruments. Very useful but very "delicate" too.
> Needs to be calibrated occasionally so I am intrigued at the fact that you are able to make "adjustments" to your unit and still maintain it in good working order. Well done.



What you are talking about are the instruments that cost many hundreds and that have an official calibration stamp, those are a lot more sensitive than these ones, as I found out.

I was almost sure that I was going to lose my $40 bucks (with freight) but, I was willing to give it a go as I have a large collection of springs, that I have been collecting, for years...!

I was quite surprised with the simplicity of the instruments "guts" and saw a very good chance to replace the spring with a stronger one, if the spring had the correct internal diameter (it uses a special brass bushing).

The electronics come out in one piece, leaving the mechanical bits, and those are easy to deal with.  I was pleased that I lost only 6% of its accuracy even though, the space that read from 0 to 100 is the exact same as before, is the pressure/resistance that the reading needle experience within that reading distance, resulting from the spring strength that, give the readings however, 50HA on the Type A unit, according to the scale shown on the 3 units available, the type D is 5.6 times stronger in its spring (from 8 to 45 ) so, 50HA on type A unit, represents 0.9HA on the type D unit.

The only way for me to know how close I am with type D unit, is to get a factory type D and compare, not that is extremely important to me however, I can perform a simple test and see what the difference is,m as I have the force of 45kg require to achieve 100%HA on type D unit so, pressing the gauge into a digital scales, and being careful enough to to read the weight scales at the precise moment the gauge pin is pressed in, right level to the flat face of the metal gauge, and I should be within a couple of KG error...!

I will do that test and will report...!

Cheers
George


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## MesquiteMan (Sep 3, 2014)

robutacion said:


> The only way for me to know how close I am with type D unit, is to get a factory type D and compare, not that is extremely important to me however, I can perform a simple test and see what the difference is,m as I have the force of 45kg require to achieve 100%HA on type D unit so, pressing the gauge into a digital scales, and being careful enough to to read the weight scales at the precise moment the gauge pin is pressed in, right level to the flat face of the metal gauge, and I should be within a couple of KG error...!
> 
> I will do that test and will report...!
> 
> ...



I would not worry too much about trying to get an accurate Shore D reading.  After all, it is just for your own reference and gives a relative difference.  Wood is typically measured with a Janka Hardness tester and its hardness is reported based on that.  I have never seen a Shore D hardness on wood listed since it is not the common way of measuring wood hardness!  I think this is primarily due to the inconsistency in wood structure and the fact that a Shore D durometer uses a tiny needle as a probe.  You can test one area and get one reading, then move over 1 cm and test again and get a significantly different reading.  Where with Janka, it is a measurement of how much force is needed to embed a .444" steel ball 1/2 way into the wood.

That said, I too bought a durometer a few years ago for the exact same thing you are doing.  It is not an official measurement of wood hardness but it gives me an idea of relative differences.  Mine is a certified Shore D durometer but I find that after the initial playing around with it, I seldom use it any more.


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## Wildman (Sep 4, 2014)

Since had no idea what a Durometer (hardness gauge) all about looked them up, you can get a model to measure wood hardness. 

Janka hardness rating used primarily for food flooring. I looked that up too.  So whether talking about a durometer reading or janka harness rating talking apples to apples they both will serve the purpose.

Since could not find or got confusing results looking up wood George talks about in his post thought this wood from down under pretty interesting:

Australian Buloke, or Allocasuarina luehmannii (buloke or bull-oak) is a species of ironwood native to Australia. Janka hardness of 5,060 pounds force, use different measurement in Australia.

Sometimes a brief description of wood characteristic also helpful because mentions woodturning and provides gluing and finishing help too!

I turned both yellow & tulip Poplar, both hardwoods by definition because lose their leaves every fall.  While not particularly hard woods had no problems with yellow Poplar.  Tulip Poplar gave me fits with tear out running back to the grinder a lot.

Bottom line thank you George, learned a lot!


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## MesquiteMan (Sep 4, 2014)

Wildman said:


> Janka hardness rating used primarily for food flooring. I looked that up too.  So whether talking about a durometer reading or janka harness rating talking apples to apples they both will serve the purpose.



With all due respect, this is not quite correct.  Janka hardness is used as the defacto measurement of wood hardness.  Every wood hardness chart I have ever seen as well as specifics for any species that show a hardness have always shown the Janka hardness.  I have never seen the Shore hardness of any wood given.  Even the Forrest Products Laboratory of the US Department of Agriculture (one of the main authorities in the US for wood properties) states the hardness as the Janka hardness.

The main reason a durometer is not used extensively for wood is due to the differences between early and late wood.  You can measure one spot and get one reading, then move over a tiny fraction and get a completely different reading.  Durometers are used mostly for plastics and rubbers since they have more uniform characteristics.  For example, PR typically has a Shore D of 78-80 while Alumilite Clear has a Shore D of 80-82.  Both can easily be verified with your own durometer testing a piece of cured material.  With wood, I may test a spot and get a shore D of 50, then send it to you and when you test it, if you happen to test in a different spot, it might be shore d 65.  Now, 50 and 65 may not seem like much difference but in the world of Shore D, that is a big difference.

I don't want to sound like a party pooper with George's thread.  I too went down the durometer path thinking it would be a great tool to test increases in hardness of wood when testing stabilizing results.  I bought the high end durometer and did the testing.  The results I was getting with a certified durometer were all over the place even within the same piece of wood.  I ended up with data that was neat but did not give me any really useful information.  I did not even find it useful as a diagnostic tool to test stabilizing results as I had hoped.  Just way too much variability in the surface of the wood.


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## robutacion (Sep 5, 2014)

Well, I tend to agree with you Curtis but, contrary to what you may have perceived, I'm not looking for official Janka hardness of my woods but, an extra tools to allow me to have "some" idea of "average" hardnesses in woods that I have/work with, before and after stabilization.

Contrary to what your needs may have been is relation to accurate data you could provided as the results of hardness readings on some of the products you represent, I confirm that yes, Janka tests are the most specific to wood hardness testings however, the same error principle can occur with the ball penetration forces required to a certain depth.

Ball or sharp pin or other inserting/penetrating shapes used, as shown in the Shore type gauges, they are all relative and prone to error however, industry requires a certain amount of accuracy in many of the products that have to be tested and that may explain why, the sophisticated test instruments use these people, are extremely expensive as they, themselves have been submitted of all sorts of calibrations and certifications...!

Sure, of all instruments out there, the Janka hardness tester, has been the most accurate, and most reliable in the multiple sample tests made to each wood species before the reading is called "official" however, the Janka tester would be as prone to inaccuracy and any of the Shore type gauges are, if the tests were done in the small pieces of wood, I have to test, the results would vary depending upon the precise location to where the Janka ball probe would be located before pressure would be applied to it...!

So, you are not "pooping in my party" at all, what you are saying is correct and I can validate that however, I was never considering to aclame these Shore D hardness gauges to be an accurate way to determine real wood hardness and much less that make its reading, even close to the Janka official readings, that was the assumption you guys made all by yourselves, I simple demonstrated that, for under $50 bucks, you can have an interesting tools that will be more accurate and easy to read than the "poking the wood with a fingernail or a screw-driver however, even as old-score as it may sound, finger-nail and screw driver tests on woods and other materials, are still being used, today with a certain degree of accuracy...!

What I did try to demonstrate is that, for those like me that, are always looking to learn something new every day (I may have the time, though...!:wink, look a little further than the eye can see and off-course  and play with new gadgets, you can learn something that can actually be useful to you, if useful to others...??? well, that is not my decision to make...!

So, all good, Curtis...!:wink::biggrin:

As for the She/Bull-Oak of mine being acclaimed to be the, Australian Buloke, or Allocasuarina luehmannii (buloke or bull-oak), I wish that was correct, I would be making some good money out of my stock, as I have almost weekly requests for the Buloke and I make always very clear to everyone that, even though the wood is tremendously similar in colour and grain/rays, and a relative to Buloke, the one that I sell and have in stock, is a combination of the Australian She-Oak and the Australian Buloke (Bull-Oak), and this was done buy generically mixing the 2 genes in a lab in the attempt to introduce into a specific area of the Adelaide Hills highway rest area and along the highway in that area, a tree species that had the characteristics of the She-Oak and the durability/hardness of the Bull-Oak in an attempt to make it more resistance to the Termites and other wood borers that do devore all the she-Oaks that grow naturally in this area, and they are lots of, while the Bull-Oak is more a desert tree and not natural or seen in this area/State.

The results looked promising for the first 10 or so years but, and as the trees started to reach maturity, they got badly infested with the damn bugs and Termites that have develop a way to get around the new wood characteristics, after that, they started to die and the new trees that generated amazingly from its seeds, never had much of a chance and they have been eaten faster that I can salvage some and share it to the word BUT, and even though one of my preferred woods, it does not have the hardness of the Buloke (Bull-Oak), not even close.

Possibly, a little harder than the common She-Oak from around here but never the same hardness as the Buloke.  
Anyone that has worked with common She-Oak will verify that, what I've got here, is not what they are used to, if the memory doesn't fail me, this very issue was discussed extensively in the Australian Woodworkers forum, 8, 9, years ago...???

The wood in reference is the #14 on my timbers list while another relative, the Australian Casuarina that was recently (couple of years back) given its own species name, as it was found that, this one had its own gene pool and therefore a species of its own, the Australian Rock-Oak that is still call Casuarina and is #49 on my timbers list...!

Here are 2 pics of each of both these woods, enjoy...! :wink:

 
 

Cheers
George


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## MesquiteMan (Sep 5, 2014)

robutacion said:


> Well, I tend to agree with you Curtis but, contrary to what you may have perceived, I'm not looking for official Janka hardness of my woods but, an extra tools to allow me to have "some" idea of "average" hardnesses in woods that I have/work with, before and after stabilization.



Never for a minute thought you were looking for "official" readings of any kind, George!  I too bought my durometer a few years ago with the idea that I would do exactly what you mention and use it for exactly the same kind of data.  I just found, after lots of data collection, that it does not even give me a good representative sampling of data points.  In one piece of spalted pecan, 3" wide x 5" long, for example, I could get readings from shore D 25  all the way up to 65, depending on where I happened to stick the probe into. Even moving a few mm over can make a big difference.   That is a HUGE swing in hardness even though the overall hardness of the piece is consistent feeling.  Even after stabilzing, I get drastically different readings.  Unless the plan is to take a lot of readings and average them out, I just did not see any benefit to the data I was collecting.

Again, just passing along my experience in going down this road a few years ago. For my own use, I did not find the data reliable or consistent enough to be meaningful or useful to me for anything more than a novelty.  Your mileage may vary!


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## robutacion (Sep 5, 2014)

MesquiteMan said:


> robutacion said:
> 
> 
> > Well, I tend to agree with you Curtis but, contrary to what you may have perceived, I'm not looking for official Janka hardness of my woods but, an extra tools to allow me to have "some" idea of "average" hardnesses in woods that I have/work with, before and after stabilization.
> ...



Sure, I understand that curtis and I thank you for giving some feedback based on your experience, that I don't mind at at, as it has been a few other issues where, we both seemed to have followed the same track, only you have been in front of me a constant distance so that means to me that, even though, we never discussed these issues, we both seem to have a very similar way of seeing theses issues and we both take very identical steps, which is becoming quite interesting...!

I can see why, this sort of test had some significance to you and the Cactus Juice, I'm sure that you tried to test the claim that the Cactus Juice would give and uniform hardness through the whole, surface of the blank, and until just recently I thought that was the case but, it has become obvious to me that, the hardness results of the stabilization with Cactus Juice and I'm certain, with any other wood stabilizer, is that, the final hardness depend upon the wood composition and self hardness.

Because the blanks that most require stabilization are softwoods, spalted, etc, they themselves have different hardness variations, depending where they are tested, this explain your results and the reason why you see that disappointing and not as useful as if the readings would be constant throughout the stabilized blank.

At the same time, that phenomenon doesn't surprised me much, and as we say in the construction world which you are most aware of, " A house is as strong as its foundations...!

On the other hand, and for the cost of such gadget, I don't think that would be a bad idea if this instrument could become another tools on the arsenal so when someone come up here and says that, they had soft wood that they don't know if requires stabilization or not, instead of trying to guess how soft it is or, how deep the finger nail goes in, that is a lot more relative and confusing than say, the average reading on the hardness gauge is ....HA, and that would be something that we all could understand and discuss.

The error margin will always be there but, is most cases, a simple average of reading at 3 points of the blank or, if the blanks has soft patches, those could be measured for hardness quite easily and the readings would mean something to us all...!

Does everyone should run to the store and order/buy one...??? absolutely not, the gauge would be useless to some people so, is just an option as dozens of other options that we, toll-shop people, like to have, even if used rarely, is that not what we do...???:wink::biggrin: 

No, I'm not even considering to sell them and I have absolutely no association, business or otherwise with anyone that does...!

Cheers
George


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## Wildman (Sep 5, 2014)

Curtis, I am not a fussy butt saying “so whether talking about a durometer reading or janka hardness rating talking apples to apples they both will serve the purpose.”  

You can buy a Durometer that will give you a ball park hardness number but have to pay attention to manufacturer’s specs and buy correct model. 

Not all wood known to mankind around the world has undergone Janka Hardness testing.  Common names are unreliable since two or more species often have the same common name.

Yes, Janka Hardness Ratings industry standard worldwide. The most common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring or decking.  Furniture industry also uses those ratings selecting woods and as a selling tool! 

Janka Scale - Janka Hardness - Janka Lumber Scale

The tabulated Janka Hardness numbers are an average. There is a standard deviation associated with each species, but these values are not given. 

Hardness of a particular wood not the only characteristic we should worry about turning wood.


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## robutacion (Sep 5, 2014)

Wildman said:


> Curtis, I am not a fussy butt saying “so whether talking about a durometer reading or janka hardness rating talking apples to apples they both will serve the purpose.”
> 
> You can buy a Durometer that will give you a ball park hardness number but have to pay attention to manufacturer’s specs and buy correct model.
> 
> ...



Interesting that Australian Buloke is not showing on that graphic and thew #1 in the world but again, the species show are a lot more used in the wood industry, particularly in flooring.

It was the Janka wood hardness data appearance that created the problem with the Buloke wood in Australia, the species is now protected after every man and their dog were cutting down every Buloke tree the could find.

Please remember that, any of these extremely dense/hard woods, are very slow growers due to the fact that, they are mostly desert trees, that live in harsh environments, forcing them to grow slow and grow small...!

People all over the world went crazy about the hardest wood in the world, they all wanted some of it and with a such head high prices, the limited number of these trees available, were chopped down almost to extinction, only some areas of reserves and national parks still have so left that, still continued to be cut down, despite of jail risks and much more...!

There is nothing special about Bull-oak, the trees are small and rough so the wood yield is small and full of holes, cracks and other faults, the wastage to get just a few pen blanks is horrendous, the older and bigger trees did once upon a time, produced big enough wood for fence posts, there should be remote areas with plenty of these fence posts still holding fences but, you would be hard pressed to get 5 pen blanks clean of defects, from a whole post that is in average 4" square x 4' 1/2 long, with the portion buried on the ground.

I doubt that we have enough Bull-Oak trees left in Australia that would would produce clean enough wood to lay a floor in a 2 bedroom house.

The less informed people, are paying good money for its imitation, the She-Oak, people are advertising Bull-Oak and charge accordingly, people don't know the difference and they will never know any better, unless they have it tested, and that, we all know, ain't happen.

Unscrupulous people strive on these situations, and no one seems to care, unfortunately. 

This is one of the cases where I wished that, they never had tested the Bull-Oak hardness, why did they, the wood would never had any commercial value for furniture, floors or construction so, a waste of time with dramatic consequences to this Aussie icon...!:frown:

Cheers
George


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## Wildman (Sep 6, 2014)

Whether rely on Janka hardness test chart or durometer designed to measure wood harness.  Hardness of a wood not the only factor you need to know when turning wood. 

You have to take into consideration where on the tree wood comes from.  Talking about whether wood comes from the base or reaction wood found in crooks, limbs, crotch, of a tree.  Also the moisture content of that wood you are about to turn.  Wet wood is never as strong as dry wood. 

Curtis mentioned early - lathe wood rings, well in hardwoods very hard to distinguish between the two in many species when wood is coming from the base of a tree.  Rings may be more pronounced in wood coming from crooks, limbs, crotch (reaction wood).  Lot easier to see early – late rings in many softwoods coming from base of the tree but not all.  Wood from softwood crooks, limbs and crotch considered tension wood again easier see early – late wood.

Depending upon where wood comes from on a tree may have more strength.  Regardless where wood comes from on a tree not very strong or stable until reaches EMC for surrounding area. 

No that is not all the information you need to know about wood to turn a pen.  I am still learning myself so will stop rambling for now.


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## MesquiteMan (Sep 6, 2014)

Wildman said:


> Whether rely on Janka hardness test chart or durometer designed to measure wood harness.



Not to keep beating the dead horse, but I am not aware of any Durometer "designed to measure wood hardness". This is after dong a LOT of research on it over the years and even going to far as to speak to the manufacturer of the durometer I do happen to own.  I have even checked into buying a machine for testing Janka Hardness  but they are just too far out of reach for me.  They start at around $2,000!  

Durometers give you Shore ratings in various different scales based on the general hardness of the group of materials you plan to measure.  I am not aware of any Shore scale for wood.  I ended up with a Shore D durometer because Shore D is for the hardest of the plastics and rubbers out there.


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## Wildman (Sep 7, 2014)

Curtis, George not the only person to use a durometer to measure wood hardness.

Durometer for checking wood hardness

Not sure what term used last week but found a vendor saying had durometer you could use on wood, should have posted the link.  Obivously cannot find it today. 

Not this Australian man’s testing method should meet with your approval. 
How Wood Hardness is Measured | MAKE

For those that find this thread getting weary but want to know how hard your wood is check out this Wood harness cart or others online.

http://www.workshoppages.com/WS/Misc/Wood-Hardness-Chart.pdf


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## robutacion (Sep 7, 2014)

Hold on your horses gentleman, this is not a dispute on what Janka wood tests are, and what durometer shore type gauges tests on wood are or should be, nor is a case of mine is bigger than yours, type thing...!

I don't give a rat's arse on the Janka wood hardness readings, they are not something that do me any good or, resolve any of the issues that made me buy a durometer and take some readings of everyday woods I work with and that show signs of all sorts of ageing, spalting, rotting and everything in between.

Even if some of my woods have a Janka reading, that information is irrelevant to me, as by simply processing the wood on the bandsaw, I know if is hard, medium, soft, or very soft.

A single small log of many of my woods, can produce half a dozen types of wood hardness, spalting stages, rotting stages and everything in between, and this was the very reason why I thought that a durometer type D could be very useful in giving some readings that I can compare with something that I and most of us is familiar with.

Regardless of how the instrument was calibrated and to what for, the benefits are very clear to me, not some much on what the digits represent in an official or wood industry related data, to me, what I wanted to achieve with this is very simple.

If I calibrate the instrument to start reading something that I decide being the low benchmark, that being a piece of true cork, as one material that we all recognise as spongy/soft, and the instrument reads 9.5 of something, who cares what the HA stands for, it could say nothing after the digits, it would serve me no different as, are the numbers that I'm interested in, and then got to the other extreme and test the wood I know is my hardest, regardless if it has a Janka reading or not, totally irrelevant here, and the readings show 86, knowing that, that same gauge reads 96 on a flat steel surface and 89 on  a patch of solid Polyester resin, I have just covered all the hardnesses I'm interested about in the woods/materials I handle/work with that are also, the same materials that many other turners around the world, have to work with from me so, the answer is very simple.

My tests are not to be compared with anything, unless, compared with other people that may have or want to have the same instrument to check their woods hardness, in a language that has nothing to do with Janka, but has a lot more to do with durometer shore D type, regardless what these instruments were originally invented for, who cares...??? really...?:wink:

Someone would ask, and about those woods that are so soft that, the durometer can't get any readings...???  Well, I made sure that I showed one example of that also, with the test on the Centenary tree #100, it doesn't need to be rotten to be that soft, this "wood" was very alive/green when I cut it and, had no resistance at all to the gauge pointed probe, I'm yet to try many other soft woods, such as the dry #31 Palm "wood".

Accuracy...?, what is accuracy is this case...??? if I'm testing a blank/board that I see has soft patches, and I don't want to put a screw driver on it or any other sharp pointed object and spoil it, is a lot easier to make the decision on what I will need to do, so that becomes "workable" to me and particular/specially to others, with my own wood stabilization gear, I see no point is offering for sale blanks that most people can't handle, sure they can be lightweight so, I can fit lots of blanks in a bag/box, and they are cheaper than the rest however, I know exactly what will happen, before I could stabilize my own blanks, I would restrain myself to put any of them on sale and when I did, I did so with lots of warnings about it but still, I had a lot of complains from people that only did look to the price and the number of blanks they could get in a 500gr parcel...!

Anyways, lets RECAP and make a few things clear, it may have been better it I had used on the thread title the word "softness" than "hardness", and again, may not have made any difference so, let me repeat this again, this thread of mine, has absolutely nothing to do with Janka wood tests and the data that is available about wood species that have been tested with such instrument, my readings have nothing to do with Janka and as far as I'm concerned, I have heard the word Janka mentioned enough times so, that's enough of it...!

Secondly, the thread was/is intended to exemplify of how very cheaply, anyone can get an instrument that is a good tool and "ACCESSORY" to use, to determine with sufficient accuracy, what I wanted to use it for and that is, have my own data of what I have to work with and then have something that can measure and determine the results of the work/processes, you put into place, such as compare the before and after.

It doesn't matter, if you don't see a need for one or not, that is entirely up to you however, if you didn't know what a durometer was, the various types, its suggested uses and the many uses the instrument can be suitable to, I believe my thread may give you some answers that you always wanted to know but you didn't know how, easy to understand, huh...!:wink::biggrin:

So, anyone that actually has questions and would like to talk a little more about the instrument that I used on my demonstration, and keep it within of what it really means, is most welcome to do so...!

Cheers
George


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## sbwertz (Sep 7, 2014)

George, that explains a problem I have...in reverse!  I inlay turquoise into fragile mulberry crown wood.  When turning, the wood often shatters at the join with the stone.


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## robutacion (Sep 8, 2014)

sbwertz said:


> George, that explains a problem I have...in reverse!  I inlay turquoise into fragile mulberry crown wood.  When turning, the wood often shatters at the join with the stone.



That's not really in reverse Sharon, depending of the hardness/softness of the wood you use of that cast, it may have needed some stabilizing before cast.  

Depending upon the way the blanks was positioned on the lathe, will determine which material (wood or resin) the gouge will cut/touch first, the transition of hard too soft is no less damaging than the other way around, those 2 very differents densities get punished in different ways and sometimes things fall appart...!

It makes good sense to soak some super thin CA at the materials joints, even if you don't see any crack or separation, believe me, they can be there and you won't see it...! 
Repeat on every joint of each blank, let it dry overnight if possible and then proceed..!

If the wood is too soft, have it stabilized first, it will save you lots of troubles later on...!

Another piece of advice is that, when you cast certain woods, 2 things can happen, if the wood was stabilized first, and the wood wasn't cooked bone dry, when you cast it with PR (the one I know of) you can get a sticky layer in between the juice surface and the resin, this layer will not allow the resin to adhere properly and later on, the 2 materials will separate partially or totally however, if you see that happening, you need to get the blanks in the oven under 70° celsius for a couple of hours.  What it happens is that, that sticky layer formed if let to dry normally it will do so but it won't bond the 2 materials but, putting the blank under this medium temp for 2 hours, it cooks the sticky surface into the wood surface without altering too much the PR brittleness so, you endup with a very strong bond as a result.

The second suggestion is that, with PR casting, if the wood is row but has the slightest amount of natural oils, when you take the molds out of the pot, the resin may seem hard/solid but, when you start cutting them appart (if a block is the result), you will notice a similar sticky layer between the wood and resin, similar to the stabilized blanks, in that case, waste no time and do the same cooking process as explained before, that sticky layer from the PR, it only stays there for a short period of time , it will start to harden as soon as air get to it but, it won't improve the adhesion between the 2 materials if you let the air dry it while, if put under the suggested temp, the resin will slightly soften and expand  towards the wood when that temp is reached, from then on, the 2 materials stay together without the need to be clamped, only in a few occasions clamping is necessary and unless you have all metal clamps, you will need to sandwich the casting between 2 solid boards and screw them together while in the oven...!

Well, there is a lot more to it but, I hope these few "clues"/suggestions can be of some use to you and others...!:wink::biggrin:

Cheers
George


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