Moisture content measurements - logs

[RealEstate]

Recently bought a cheapo £20 digitial meter from my chimney sweep. Seems to give reasonably consistent readings for any given split log. I've been measuring various h/w cut logs from freshly cut/split, to 'kiln' dried for a coupe of days beside the stove. Have the following observations:

 

Readings are usually higher measured on the ends of the log (often a lot higher) than on the sides, including when freshly split before measuring.

 

When measuring the sides, no significant difference across or parallel to the grain.

 

The bark invariable has very high readings usually >30%. Peeling off the bark often reveals visible dampness underneath.

 

Any comments appreciated - Happy New Year

[Alycidon]

Sounds like you have some poor quality logs.

 

Split a log, measure the center of the newly exposed face, that is the real moisture level.

 

Depending on your stove put anything above 18% aside to dry for next winter, use anything below that. If your stove is a modern contempory woodburner with a terciery air system that can take advantage of very low MCs then try and use logs below about 10%.

 

If the product is kiln dried properly then you should be looking at MCs well below 10%. I bought some KD logs in the summer than averaged about 3%. These have now risen to about 8%- 10% externally thanks to the moisture in the air. Internal is about 5%.

 

A

[RealEstate]

Yes many are poor quality, been stacked outside uncovered for several months.

 

So would you expect the end-grain measurement to be less than a newly exposed centre measurement?

 

And what about the bark - seems to take a lot of drying out?

 

TIA

[gdh]

The bark isn't too hard to dry but as you say it's the damp layer underneath that can cause problems, nature can be awkward...

We like to sell our wood below 20% as a maximum but we usually read 0 on a moisture meter because we keep it in the drying shed until delivery (I know that's technically more like 6%).

 

I found that if you dry wood down to say 14% then it's often double when split, it still burns perfectly though, I go on the surface reading myself as that seems to show what will burn well. I think the official advice is to measure across the split side of a log.

 

And happy new year.

[gdh]

Also it's interesting that certainly wood who are one of the biggest suppliers that I know of market their kiln dried logs as below 20% average. I wonder if that's split and measured or not.

 

On average I would personally want around 15 but it's easy enough to burn anything up to 25 with a decent fire.

[Woodlover]

A big company near me that sells logs has put me off buying logs , after repeatedly selling me soft wood logs that are 28-32%, I cannot buy again...the logs took ages to get going and produced little heat.The ton load of wet logs I had lasted me longer than a ton of dry because of the crap fire it produced did not make me want to lite it so much, and the slow burn as it was so wet made it last...in other words if this company dryied there logs right then I would have ordered more ,burnt more,and they make more money.

It took me a few years of having bad logs before I got myself a moisture meter,and since then I now find my own wood.If I go to a forest I know ,where there are some trees on the ground that were felled only 8 months ago,chop it up and measure,its 23-28%,mostly Ash...So why the hell this company has 30% really winds me up, but they are always busy.

[briquette_seller]

A big company near me that sells logs has put me off buying logs , after repeatedly selling me soft wood logs that are 28-32%, I cannot buy again...the logs took ages to get going and produced little heat.The ton load of wet logs I had lasted me longer than a ton of dry because of the crap fire it produced did not make me want to lite it so much, and the slow burn as it was so wet made it last...in other words if this company dryied there logs right then I would have ordered more ,burnt more,and they make more money.

It took me a few years of having bad logs before I got myself a moisture meter,and since then I now find my own wood.If I go to a forest I know ,where there are some trees on the ground that were felled only 8 months ago,chop it up and measure,its 23-28%,mostly Ash...So why the hell this company has 30% really winds me up, but they are always busy.

 

What did this company say when you pointed this out?

[cornish wood burner]

Presumably you have a spike type meter. These meters work on electrical conductivity so the spikes go further into the end grain or bark. This gives a better electrical circuit so end grain reading could well be higher.

These meters are useful as a guide but often can be inaccurate especially at the low and high end of the scale. If you want a meaningful measurement then weigh and oven dry.

You need some kitchen type scales that weigh to a gram.

First weigh your wood.

Dry in a slow oven 60 deg ish for 24 hours until the wood stops losing weight.

Divide the weight loss by the original weight and you have the moisture content as a normally used wet basis.

If you do this for a few different pieces then you will get an idea of your meters accuracy throughout the range.

[Woodworks]

Also it's interesting that certainly wood who are one of the biggest suppliers that I know of market their kiln dried logs as below 20% average. I wonder if that's split and measured or not.

 

On average I would personally want around 15 but it's easy enough to burn anything up to 25 with a decent fire.

 

If your wanting logs at 15% you're going to need kiln dried if you're out in the west of the UK. This winter being so wet and humid makes it basically impossible to dry below 20%. At 10 C and 90% RH your logs will sit at 21% (99% RH here this morning )

 

Wood Equilibrium Moisture Content Calculator from Wood Workers Source.com

[Wood wasp]

Presumably you have a spike type meter. These meters work on electrical conductivity so the spikes go further into the end grain or bark. This gives a better electrical circuit so end grain reading could well be higher.

These meters are useful as a guide but often can be inaccurate especially at the low and high end of the scale. If you want a meaningful measurement then weigh and oven dry.

You need some kitchen type scales that weigh to a gram.

First weigh your wood.

Dry in a slow oven 60 deg ish for 24 hours until the wood stops losing weight.

Divide the weight loss by the original weight and you have the moisture content as a normally used wet basis.

If you do this for a few different pieces then you will get an idea of your meters accuracy throughout the range.

 

 

Very interesting but if someone can't tell difference between a wet log and a dry log from looking at it and picking it up then they shouldn't be burning wood. Likewise if they can't organise their log shed accordingly.