Moisture

[Garno]

You can blame Eamonn [MENTION=165]silver[/MENTION] for this

Whilst enquiring about turning Ebony [MENTION=165]silver[/MENTION] posted a wonderful reply, in it he touched on moisture content.

This will be no surprise to you all, on the strength of that post I went rushing out and purchased a moisture content reader. I think really I should of put a bit of thought into what I needed one for before splashing out the £16.99 (And that's with £3 off) AZUNO Wood Moisture Meter, Pin-Type Water Leak Detector with 8 Modes, Digital Moisture Tester Drywall and Wood, Backlit LCD Display with Audible Alert, Wood and Building Material Dampness Inspection : Amazon.co.uk: DIY & Tools

Anyway it arrived yesterday and is rather impressive for the price with 8 different built in calibrations covering around about 100 different wood species. [MENTION=165]silver[/MENTION] mentioned a moisture content of between 5% - 10% for the Ebony Would this apply to all wood types for pen turning or do some woods need a higher or lower content? I can find very little info anywhere.

 

[silver]

Anyway it arrived yesterday and is rather impressive for the price with 8 different built in calibrations covering around about 100 different wood species. [MENTION=165]silver[/MENTION] mentioned a moisture content of between 5% - 10% for the Ebony Would this apply to all wood types for pen turning or do some woods need a higher or lower content? I can find very little info anywhere.

In reality Gary, the wood needs to be dry enough for the environment its going to live in. If its in the UK in most homes as a general rule I aim to get it down to less than 10% however with the likes of Oak I have "got away" with 15%.

With my boxes I need to have them at less than 10% as the lids can warp if they are any higher.

That's my experience and find that my aim is to get them as dry as I can.

 

[Curly]

The problem with the meter you bought is that the pins have to penetrate into the wood in order to get a reading that is more accurate. Trying it with ebony will probably result in bent pins and then you are faced with the holes in the pen blank. Try it on a softwood, a 2x4 or as you guys say a 4x2, and you will see the reading with the pins in the surface will be different than a reading with the pins pushed deep into the wood. You will also get a different reading on the end grain of a dry board compared to a reading of a freshly cut piece. I don't know if a pin less moisture meter will work on a piece as small as a pen blank but it might if several were placed side by side and read together. The most reliable method is to weigh the blank with an accurate scale, taking readings every few days or weeks until it doesn't change. Then it will be at equilibrium with your environment. It can take many months with ebony and should be in the house if the shop isn't heated/cooled the same. The meter you bought is good for general woodworking and checking bigger wood for turning like bowls.

Pete

 

[Garno]

The problem with the meter you bought is that the pins have to penetrate into the wood in order to get a reading that is more accurate. Trying it with ebony will probably result in bent pins and then you are faced with the holes in the pen blank. Try it on a softwood, a 2x4 or as you guys say a 4x2, and you will see the reading with the pins in the surface will be different than a reading with the pins pushed deep into the wood. You will also get a different reading on the end grain of a dry board compared to a reading of a freshly cut piece. I don't know if a pin less moisture meter will work on a piece as small as a pen blank but it might if several were placed side by side and read together. The most reliable method is to weigh the blank with an accurate scale, taking readings every few days or weeks until it doesn't change. Then it will be at equilibrium with your environment. It can take many months with ebony and should be in the house if the shop isn't heated/cooled the same. The meter you bought is good for general woodworking and checking bigger wood for turning like bowls.

Pete

Typical just typical,

Not only have I purchased something I don't need but I am also using it wrong

I just thought I needed to press the prongs against the wood.
I suppose that explains why I had a reading of 6.2% on all of the blanks I tested (Not properly tested)

 

[Curly]

Garno don't take this as an attack but generally you seem to be impulsive. You get excited and buy before doing much research. Maybe it is time to take a longer look and ask questions before succumbing to the urge to get. The members will help if asked. The moisture meter will come in handy down the road and it is so much more affordable than the ones selling a decade ago so it isn't a total loss. You will need it at some point and be glad you have it, just take out the batteries before you put it away. :wink:

Pete

 

[Garno]

Garno don't take this as an attack but generally you seem to be impulsive. You get excited and buy before doing much research.

Pete

You are indeed correct

It is something that cannot be helped, usually I am not even aware I have done it until a parcel arrives.
Mrs G gives me a little spending money each month.

I no longer have a comprehension of money or the value of things, £1 £10 £100 all are the same in my head, I know £100 is higher than £1 yet I forget it when purchasing, Things are slowly but surely getting worse but not to worry

These days I forget what I have posted so I print off the answers then forget where the prints are.

I can hold hand on heart and say I did not take your post as an attack and thank you for it

 

[Dalboy]

Easy to say but every time you get the urge to buy stop and think to yourself do I really need this or that. If you order on a computer then hang a very big sign in front of you to remind yourself. This may prompt you to stop and even ask questions before buying.

It may save you money or at least let you save for something you really need that is a lot dearer.

And if you can't remember all of that just remember that if you want to impulse buy I could do with a larger lathe

 

[silver]

The most reliable method is to weigh the blank with an accurate scale, taking readings every few days or weeks until it doesn't change. Then it will be at equilibrium with your environment.

Pete

Gary [MENTION=2366]Garno[/MENTION], while I agree with Peter in many ways. But weighing is still fraught with problems.

Size of stock is critical - something like an 200x200mm bowl blank with 25% Moisture will weigh considerably heavier than a 20x20 pen blank with 20% moisture content.. So the % of weight will be so much smaller than the bowl blank that you will need a set of scales that have 0.05g weight capabilities.

I agree that the moisture meter will only get what the pins will measure, but in my experience moisture will wick out the ends of the grain easier than it comes out the side of the grain. If you were putting the pins in the end of the blank then it’s not as critical to having pin holes in the ends.

A good way of drying a blank then you could pop them in the microwave for 20 seconds or so on low power a couple of times a day for a week then see how the moisture measures. It usually wicks out the end of the grain.

You can leave it in your house for a long time but TBH you won’t know how it’s drying. You need to force dry it manually,

 

[Geoff Kent]

I seem to remember reading an article by Peter Childs on moisture content.He put several pieces of wood of various species in his woodstore and various rooms in his house.The moisture always settled to 12%.Re distortion,I have found thin walled bowls and boxes to be the worst culprits.I always tell my customers that some distortion MAY occur.

 

[silver]

I seem to remember reading an article by Peter Childs on moisture content.He put several pieces of wood of various species in his woodstore and various rooms in his house.The moisture always settled to 12%.Re distortion,I have found thin walled bowls and boxes to be the worst culprits.I always tell my customers that some distortion MAY occur.

And [MENTION=2366]Garno[/MENTION]

If you have a look at this link under the seasoning process you will see the research that you are talking about.

How to make use of unseasoned green fresh cut wood

However, the comment that is particular is this

“The percentage of water in the wood may get as low as 5% but there always will be some water left in there.
If you switch off the heating for a month or two and the air gets moister, then the wood will slowly gain water until the percentage water content achieves the value for an unheated room in a house which is typically 12%.” (Peter Childs)

My first comment still stands as you need to get Ebony down as low as possible before drilling and turning, if moisture levels increase in the finished pen then it’s only going to expand and not shrink. Shrinking is not good for pens as it will likely end up cracking and splitting.

It’s important to get the wood down to the moisture content of its final home, or there about. Switching the heating off for several months and moisture increase will happen very slowly, so no trauma to the wood as it’s happening slowly.

If you turn wood when it’s 15% then bring it in to a centrally heated house in the middle of winter then that is happening very fast, the wood can’t cope with that.

All I’m saying is prepare the wood for where it’s going to live… which if you read what Peter has written is saying exactly that.

 

[TVS]

To be perfectly honest I have never used a moisture meter in my life if I think a wood needs to be dryer I bring it indoors but I only do that if like Eamonn said when making a lidded box all wood when finished will move as the moisture content in every room is different and all woods will respond to that some more than others I remember fitting a pine door on our bathroom and had a shower and couldn't get the door open after LOL regarding Ebony it can be such a temperamental wood I much prefer African black wood and think it finishes so much better in saying this I buy my wood and keep it stored in my nice dry insulated & heated shed for years before using it so mostly its nice n dry to what content I dont have a clue LOL

 

[Bill Mooney]

I’m like Woody, I never use a meter & I don’t have a problem.
I sometimes think you can overthink things & create problems in your mind which aren’t really there or aren’t relevant. I just enjoy my turning but then I’ve been doing it for a long time.

 

[Neil]

Issues with ebony are not purely related to shrinkage. One of the traditional methods of harvesting some African grown species is to ring bark them and leave them standing dead for a couple of years. The tree is then felled. And it crashes to the ground inducing shattering. Got offered once a whole container of Asian striped ebony. Utterly useless, it had been poorly felled, poorly dried and was worthless.

Wood doesn’t shrink uniformly, it is ansitropic. Along its length the shrinkage is less than 1 per cent and is more or less immaterial.the other two shrinkage stats, tangential (pith to circumference) and radial (around its circumference) are more relevant and the greater the difference, the more unstable the wood is. Tangential shrinkage is normally around 3-5 per cent and radial can be up around 12 per cent. The greater the difference, the more the movement will be which leads to significant bowing or cupping. The more naturally the wood has dried, the more stable it is, air dried is more stable than kiln dried. However, regardless of how dry a wood is or appears to be, when it is subject to conditions different from its own state of equilibrium, it will distort unevenly. And, if you have altered it’s shape in any way, the expansion will be different from its original contraction and therefore induce different stresses.

Which means it might split! Particularly if the wood is dense. The denser the wood the slower the change to adjust to the ambient conditions, the more unequal the change and the greater tendency to turn into untipped swan vestas!

All said and done, some of the greatest shocks to wood occur from vigorous sanding. So, if you get a tree, fell it, dry it, then change its shape, drill it, turn it, sand it excessively (most do) when it’s now wafer thin, it’s hardly surprising if it splits occasionally, and I hasten to suggest that it probably doesnt give a monkeys if it was at 10 or 12 pc when you started, it’s just one of those things…..

Bear in mind that at felling the rh level will be at around 35 pc, species dependant, and very quickly the water level will drop to 23pc, this is due to the loss of free water. Thereafter the slow process of drying begins, the long crawl to 12 pc or less with the loss of the structural water.

How long does it take to air dry wood, another interesting myth!

 

[Garno]

Issues with ebony are not purely related to shrinkage. One of the traditional methods of harvesting some African grown species is to ring bark them and leave them standing dead for a couple of years. The tree is then felled. And it crashes to the ground inducing shattering. Got offered once a whole container of Asian striped ebony. Utterly useless, it had been poorly felled, poorly dried and was worthless.

Wood doesn’t shrink uniformly, it is ansitropic. Along its length the shrinkage is less than 1 per cent and is more or less immaterial.the other two shrinkage stats, tangential (pith to circumference) and radial (around its circumference) are more relevant and the greater the difference, the more unstable the wood is. Tangential shrinkage is normally around 3-5 per cent and radial can be up around 12 per cent. The greater the difference, the more the movement will be which leads to significant bowing or cupping. The more naturally the wood has dried, the more stable it is, air dried is more stable than kiln dried. However, regardless of how dry a wood is or appears to be, when it is subject to conditions different from its own state of equilibrium, it will distort unevenly. And, if you have altered it’s shape in any way, the expansion will be different from its original contraction and therefore induce different stresses.

Which means it might split! Particularly if the wood is dense. The denser the wood the slower the change to adjust to the ambient conditions, the more unequal the change and the greater tendency to turn into untipped swan vestas!

All said and done, some of the greatest shocks to wood occur from vigorous sanding. So, if you get a tree, fell it, dry it, then change its shape, drill it, turn it, sand it excessively (most do) when it’s now wafer thin, it’s hardly surprising if it splits occasionally, and I hasten to suggest that it probably doesnt give a monkeys if it was at 10 or 12 pc when you started, it’s just one of those things…..

Bear in mind that at felling the rh level will be at around 35 pc, species dependant, and very quickly the water level will drop to 23pc, this is due to the loss of free water. Thereafter the slow process of drying begins, the long crawl to 12 pc or less with the loss of the structural water.

How long does it take to air dry wood, another interesting myth!

Thank you for taking the time to write this,

Swan Vestas now there's a blast from the past

 

[Neil]

Spot the deliberate mistake! The definition of tangential and radial contraction, are the other way round, radial contraction is at right angles to the growth rings and tangential around the circumference.