How to Properly Test Wood Moisture Content

thephotohound Posted By thephotohound, Aug 20, 2007 at 11:43 AM

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  1. thephotohound

    thephotohound
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    I bought a moisture meter last year... just a cheap 4 prong digital one off eBay for $25. Seems to work well!

    I just want to make sure my common sense it working OK this morning... If I just pick up and test a seasoned split and it reads 20%, then I split it and test the fresh part (inside), and it's 37%, the moisture content is still 37%, right?? Or is the exterior moisture content more important, because by the time the interior portion actually starts to burn, it's dried out from being in the firebox??
     
  2. babalu87

    babalu87
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    Correct method
    The 37% is the moisture content of the wood. When a split has more than the ideal moisture (15-20%) it has to be driven off as steam and steam in a woodstove is a reduction in its efficiency/heat output or in laymans term BAD

    That wood probably needs another year to dry out, I get readings of around 40% on fresh cut wood.
     
  3. n6crv

    n6crv
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    This has to do with the same question. what happens when wood that that has seasoned for a couple of years gets wet from rain. Does the seasoning have to start over? Or during the winter when it gets covered with snow? Thanks
    Don
     
  4. Todd

    Todd
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    Babs is correct, split the wood and take readings. You should be somewhere around 15-25% for dry wood. Also check your moisture meter directions to see how far you stick the tines into the wood. Mine says about 5mm. I noticed a big difference in readings between pushing the tines in all the way or just 5mm.
     
  5. DiscoInferno

    DiscoInferno
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    Brief wetness from rain generally won't soak into non-punky wood much, and will evaporate when the sun comes back out. With snow cover it depends on how long and if the temps stay below freezing or ping-pong above and below. The latter is a good way to have soggy wood, as the snow holds the water next to the wood. And if you get a lot of snow, then an extended spring melt may result in soggy wood also. Best to just brush it off before it melts.

    The working theory seems to be that "seasoned" and "dry" are somewhat different properties, and that "wet seasoned" wood will dry again more quickly than will "wet unseasoned" wood due to a different distribution of water in and around the cells. YMMV, I try to dry wood only once.
     
  6. Highbeam

    Highbeam
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    I use a moisture meter too and use the inside reading as the truth. I shoot for 20% maximum and find that a 15% is much much better to burn. I only spot check and if I pick up a particularly heavy split then I might check that one too, and split it extra small if it is on the wet side. Once I establish that the pile is in good shape then I don't check as often. The gadget is great fun.
     
  7. Vic99

    Vic99
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    Hey Highbeam, how do you like the Heritage? I'm hopefully getting one that vents out of the my centrally located fireplace. First I have to remove a ton of trim wood to make code. Do you burn 24/7? What size home? If you had to do it over again, would you get another Heritage? Thanks.
     
  8. Highbeam

    Highbeam
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    The Heritage is installed as of last week. I have yet to get a permit so all I have burned was a couple of sheets of newspaper for fun. I will burn 24/7 in a 1700 SF rambler with little insulation, single pane windows, and no floor insulation. We love the looks of the stove and soapstone has a strong reputation as a heater. I removed a masonry fireplace with a Lopi insert that had a blower which we disliked. So far so good, it looks very nice up on the hearth in my living room with outside air plumbed, rear heatshield, and double wall pipe.

    The attached photo is from one of the forum's members and was an inspiration.
     

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  9. BrotherBart

    BrotherBart
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    Those suckers are too pretty to light a fire in'em. They need an LCD TV screen in the door.
     
  10. Harley

    Harley
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    LOL, BB.... they is even "purdier" when you gots a good fire goin' in 'em.
     
  11. Highbeam

    Highbeam
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    I'm pretty sure that's your stove Harley? I get the inspection on Wednesday, wifey wanted heat today.
     
  12. Harley

    Harley
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    It is. I'm sure you will really like it. BTW - I did re-support the T in the back that you see in the picture, and got that mess in the original fireplace opening cleaned up.
     
  13. bcnu

    bcnu
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    Think I'll get a moisture meter to see how my wood is doing - thanks for the info. My Hearthstone Homestead was installed a few months ago and I still haven't done the initial fires. If it heats as well as it looks - then I'll be a happy camper. I'll put up some pics when we light 'er up.
     
  14. R&D Guy

    R&D Guy
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    AAh, my dog use to do the same thing when I had a wood stove!
     
  15. Havlat24

    Havlat24
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    False... Moisture meters cannot accurately measure moisture content in wood past the fibre saturation point of the wood being tested. Most electronic hand held moisture meters are only accurate between the ranges of 5-25% moisture content.
     
  16. Harley

    Harley
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    Well - that is true, but that doesn't mean that they cannot be used as a "guide", as to whether or not the wood is wetter or dryer than you would like, and then you just get a "feel" for it, so for some - it's probably a good tool. Even the most expensive moisture detection devices will not really give 100% certainty as to the moisture content of wood (or a lot of other materials for that matter). There's only one way of determining it with that degree of certainty, and that's by weighing before, and then cooking off the moisture <at a lower temp, so you are not burning off the VOC's along with the water>, and then weighing it after. I don't think most would want to send their wood to a lab to get a real accurate reading.

    I'd say - use those things as a guide if you like - take a chunk and split it in 1/2 - see what the reading is and see how it burns.
     
  17. Havlat24

    Havlat24
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    I agree. I was just trying to point out that the moisture content in this fellows wood is probably much more than 37%...as most of those prong type meters max out around that reading.
     
  18. begreen

    begreen
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    Agreed. If you split it and it reads >25%, it's not dry. You want it to read below 20% all the way through. Burning it to dry out the interior core is not the way to go. It will burn with less heat and produce more creosote.

    Eventually when you know the wood, you can tell it's really dry by weight. And if you split it, try holding it up to your cheek. It's still damp it will feel cool.
     
  19. bcnu

    bcnu
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    BeGreen, should your pants be up or down when holding the wood against your cheek :red:
     
  20. begreen

    begreen
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    LOL. Let's just say that you need to turn the wood to the other cheek :)
     
  21. Harley

    Harley
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    Oh, I do agree with you, and on either end - they are not going to be real accurate, but probabably a decent guage to use if someone is not really sure of how dry the wood is - split the "test" piece and take a reading - if in the upper 20-30% - maybe not quite ready for prime time yet - but if the reading is is the mid to lower 20's - it should be good to go - after a little while - you should be able to tell whether or not the wood is ok to burn without using the meter.
     
  22. BrotherBart

    BrotherBart
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    I have a moisture meter but no matter what it says when I hear "Yo! Bart! It is getting cold up here!" from upstairs then I know that the wood is ready.
     
  23. 11 Bravo

    11 Bravo
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    Quite a difference. Picked up a reader from Harbor Freight for $15. Was stickin the prongs in the end of the wood in my pile I cut /split/stacked in April. Was reading 10-15%, thought was a bit low. I split a few open, tested the inside and now reading 20-30% or so. That's more realistic. Thanks for the info.................
     
  24. Todd

    Todd
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    Get ready to laugh. Here is another way to see if your wood is ready. I think Babs told us this one awhile back. Take a split and rub some liquid soap on one end, then wrap your lips around the other end and blow. :red: If the wood is dry it will blow bubbles. HA Ha, this actually came from the Morso web site. I know some of you will try it.
     
  25. thephotohound

    thephotohound
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    All great comments... Thanks...

    I know that a $25 moisture meter isn't going to be extremely accurate, but I just wanted to get an idea. Seeing this is just my 2nd year burning, I assume it will be a few more until I'm really comfortable with eye-ing it up and being able to tell.

    In fact, because of my readings (some was 37%), I am picking up a cord of 3 yr seasoned oak for $50, in order to give my other 3.5 cord some additional time to dry...
     
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