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Deconstructing Denniswood

Post in 'The Wood Shed' started by Battenkiller, Oct 20, 2011.

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  1. Battenkiller

    Battenkiller Minister of Fire

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    Tony (Fire_Man) sent me two splits of firewood he got from Dennis at the Woodstock/Hearth.com get-together. I got them the other day and immediately began to analyze them for moisture content, both with my little blue Harbor Freight meter and using the extremely accurate oven-dry method.

    I got the following readings after re-splitting:

    White ash - 15% MC outside, 28% MC inside. I used the Delmhorst species correction chart to determine the correction for both readings. I subtracted 3 points from the high reading (chart only goes to 24%, so I applied the maximum amount given in the table), and 1 point from the low reading. I added both readings together and divided by two to get the average MC for the entire split - 19.5% MC.

    Black cherry - 13% MC outside, 15% MC inside. To correct for species, I added 1.5 points to both readings (see table below), then added them together and divided by two (as above) to get an average MC for the split of 14.5% MC.

    [​IMG]

    [​IMG]


    I took each half-split and made several 1" thick cuts along the length on the bandsaw. This was done to get wood samples along the entire length of the splits. Then I chopped them into smaller chunks about 1"x1" in order for them to dry faster. Finally, I placed the small chunks from each sample into a pre-weighed plastic container and weighed them to the nearest 0.1 gram on the triple-beam balance. I subtracted the weight of the container from the total to get a starting weight for each sample:

    White ash - 306.0 grams
    Black cherry - 283.2 grams

    I put the chunks on a dinner plate and microwaved them on high for 2 minutes, stopping every 30 seconds to loosely toss the pile. After four consecutive 30 second cycles, I placed the chunks back into the pre-weighed container and weighed them, alternating the samples each time and recording both weights as they changed. After I got three consecutive readings that were unchanged, I recorded the final weight and placed them into a pre-heated 220F oven overnight. The following morning, I weighed each sample to see if the weights had changed from the microwave drying (they hadn't).


    Final weights were as follows:

    White ash - 251.8 grams (water lost = 54.2 grams)
    Black cherry - 243.5 grams (water lost = 39.7 grams)


    I used the following formula to get the dry-basis MC of the samples:


    Total water lost (grams)/final oven-dry weight (grams) x 100 = %MC dry-basis.


    [​IMG]


    I determined the actual moisture content of the splits to be as follows:

    White Ash - 22% MC
    Black cherry - 16% MC



    In both cases, my meter gave a slightly lower reading than the oven-dry method showed. The meter said the white ash was at 19.5% MC while the oven-dry method proved it to be 22% MC. The black cherry read 14.5% MC on the meter, while the actual MC was 16%.


    [​IMG]



    The moisture meter measures wood using dry-basis calculations, but the wood heating industry uses another method called the "wet-basis" calculation. This is a more intuitive and useful way to visualize the water remaining in the wood as a percentage of the original weight as opposed to a percentage of the oven-dry weight. To convert the meter reading to wet-basis, just use the following formula:


    Wet-basis reading = meter reading/1 + meter reading x 100



    For the white ash, that is .22/1.22 = .18 x 100 = 18% MC.
    For the black cherry, that is .16/1.16 = 14% MC


    And that's all, folks. My thanks to Tony for spending the time and money to send this wood my way. We were both extremely curious to see exactly what the moisture content of the infamous ancient Sav-ash is, so now we know. My guess is it got down this low a long time ago and basically stayed there all these years. No sign of punk after 9 years in the stack, just good, seasoned firewood at the optimum moisture content.

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  2. Flatbedford

    Flatbedford Minister of Fire

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    Must have some time on your hands! Nice presentation.
  3. snowleopard

    snowleopard New Member

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    Ah, but did you try cleaning up spilled grape juice with it?
  4. Battenkiller

    Battenkiller Minister of Fire

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    Sav-ash... the quicker picker upper. :lol:
  5. oldspark

    oldspark Guest

    And now we know the rest of the story, cool I found your results interesting, I guess I am a wood nerd, a werd.
  6. fossil

    fossil Accidental Moderator Staff Member

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    You've got some sort of real problem, BK. (And this observation from an engineer with lifelong OCD). :lol: Rick
  7. Battenkiller

    Battenkiller Minister of Fire

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    Hey... Tony put me up to it. Blame him, he's an engineer as well. :lol:
  8. golfandwoodnut

    golfandwoodnut Minister of Fire

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    Dennis will probably say, "What do you need all this stuff for?" Just split the wood and leave it sit for 3 or more years and it will be ready to burn. But then again he is the master.

    Was the wood really that old? I thought he gave most of the really old stuff away and cut alot of Ash in the last couple of years.
  9. Jags

    Jags Moderate Moderator Staff Member

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    You know better than that - "wood is not a sponge".

    Nice work BK. I'm with ya in saying that the wood probably sat the last 6-7 years at a stable "at rest" point. Don't let Rick poke fun at ya. I heard he folds his dirty laundry. %-P
  10. pen

    pen There are some who call me...mod. Staff Member

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    and to think someone accused me of Omphaloskepsis a few weeks ago.

    So'd you burn that stuff yet?

    pen
  11. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Just wait until next year!!!!
  12. Battenkiller

    Battenkiller Minister of Fire

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    Well, truth told, I'm a bit afraid of it. If the regular Sav-ash burns so well, what will the high-test oven-dry stuff do? 'Fraid it might explode in there. :p `
  13. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Now for the engineers amongst us. Why did Tony have such a difficult time splitting that wood?
  14. Battenkiller

    Battenkiller Minister of Fire

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    I have no clue. Split like a dream with just an axe, both pieces. What'd he use, one of those newfangled Fishkers?
  15. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Tony used a splitting maul driving a wedge into it.
  16. maxed_out

    maxed_out New Member

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    Nice work BK. Ties right in with some of your previous work as well. This and the combustion/efficiency charts you did tied it all together for me. thanks.
  17. Battenkiller

    Battenkiller Minister of Fire

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    No problem, glad to help out. :)

    I'm weird, I know, but this is fun stuff to do. Especially when I've been stuck at a computer desk for six weeks looking for a new home before I get kicked out of here in six more. :ahhh: Not much to do but sit around and wait for the realtor to call and tell me when we can see yet another ugly house to not make an offer on. After several weeks of that, these projects are like mini-vacations.
  18. fossil

    fossil Accidental Moderator Staff Member

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    It's really not folding so much as just turning it inside out. %-P
  19. Battenkiller

    Battenkiller Minister of Fire

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    Ah-ha! Wrong weapon for small wood IMHO.
  20. Blue Vomit

    Blue Vomit Minister of Fire

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    BK,
    Just curious... in reference to your MC reading table, can you explain why certain species read higher on the MM while the other species read lower in relationship to the acual MC? Does it have to do with the density of the species? I was under the impression that my MM would give me a slightly higher reading than the actual MC. Apparently this is not true for my cherry?
  21. Llamaman

    Llamaman Member

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    glad you are playing with Dennis' wood and not mine
  22. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    What a coincidence BK. Exactly how I test each of my splits.
  23. Battenkiller

    Battenkiller Minister of Fire

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    Density has a role, but it's mostly the amount of extractives in the wood that is the major player. No way to predict the changes in resistivity in different woods, each species (and sub-species) would have to be checked against the oven-dry method for accuracy. This is why I say that meters are fun and useful, but they are not something you just jab into the wood and get 100% reliable results with. The oven-dry method, however, is foolproof. As long as you weigh carefully and you don't set the wood on fire, you will get results that are near 100% accuracy. You don't even have to have an idea what species it is since all you are doing is slowly driving off all the water and taking before and after weights. But... it is just a wee bit more time consuming than using a meter.
  24. MasterMech

    MasterMech Guest

    So let me get this straight, you guys are FedEx-ing, UPS-ing, USPS-ing splits around the northeast now? LMAO. Has any other Hearth.com member had the honor of his splits being shipped around the country for analysis?

    Battenkiller might be on to something. There's prob money in opening up his own "wood lab" lol. Serious burners could send in samples for a full analysis and receive a detailed report back. Much like I do with oil samples!
  25. Dune

    Dune Minister of Fire

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    Why, you never UPS firewood?
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