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Thread: Moisture Content Doug Fir

  1. #1
    Join Date
    Jan 2017
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    MT
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    Moisture Content Doug Fir

    I originally posted this in the Kiln Drying forum but got no response. Hoping to get some input here.

    Doug Fir Breakfast Bar Slab
    I am building a breakfast bar using a slab of Douglas Fir that is 2X16X8 feet rough and will probably finish about 1-5/8 thick once the cup is planed out. I got the wood from the mill down the road and it is dried to about 10 percent moisture. I have the slab pretty flat now but have not started any finish planing. My question - where I live, the wood is going to probably stabilize at around 6 percent; should I let it sit for a while before I finish flattening or go ahead and flatten it and let it acclimate? Right now it is in my temporary shop which is heated to about 55-60 degrees and should have similar moisture as the house.
    Regards,

    Kris

  2. #2
    Join Date
    Oct 2007
    Location
    New Hill, NC
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    2,568
    Kris, slabs are more prone to cupping than normal lumber. If I were you I would move the slab into your heated house for a couple of weeks and place it in a location where you can keep a gentle airflow across it. By all means dry it down below 8%

    When you finish it, it is very important to finish all sides with the same number of coats, same thickness of finish. Over the long term this will help to keep it stable.

  3. #3
    You might consider some type of batten underneath the slab, like a dovetailed batten that runs most of the width across the grain on the slab in a couple or three different equally spaced spots along the length of the slab. This will help to mechanically hold the slab flat, but allowing it to reach its equilibrium moisture content is definitely of the highest importance.

    Do you know when the slab was first sawn and how long/in what conditions it was dried before you took possession of it? This may help to inform advice for your next step.

    How much have you taken off of it so far and has it cupped substantially from that?

    Sometimes there's no quick and dirty answer to this type of decision making.

  4. #4
    Join Date
    Jan 2017
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    MT
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    Thanks Scott and Phillip. I purchased the slab about two weeks ago. The mill I got it from kiln drys to around 10 percent. The slab had been stored outside on a rack and under cover and I got it near the bottom of a stack of non-stickered slabs. Talking to the yard hands I think it had been there a while. I just purchased a moisture meter and confirmed the moisture at around 10 percent in several places. I have removed about 3/8 of an inch of the total thickness. It does not seem to have cupped any since I started. I finally got my workbench up to the new place last weekend and decided to plane this slab by hand. It was a workout. The pictures here are when I had just started on the convex side and after I flipped it and started on the concave side. I have both sides pretty flat now and I planed the edges this evening. I will plan to take it in the house a set a fan on one end. The bar is going to fold down and while I was considering battens the brackets I got are pretty stout and would probably serve that purpose. I may need to slot the outboard holes in the brackets to allow for movement.
    Attached Images Attached Images
    Regards,

    Kris

  5. #5
    Join Date
    Jun 2008
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    So Cal
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    3,730
    That's a nice slab Kris, A good choice for a table top with the cathedral grain running right down the middle.
    Df one of my favorite woods.
    Aj

  6. #6
    Join Date
    Aug 2013
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    Nice, I really like that!
    If it's flat now I would build a system of battens for it currently, or if you have a mounting setup I would mount it and if it moves plane it again.
    DF finishes beautifully off the plane, so I would continue on through to a planed finish without sanding if you can do so, it will help it in service as a bartop as well.
    Bumbling forward into the unknown.

  7. #7
    Join Date
    Jan 2017
    Location
    MT
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    698
    Andrew - yes, it is a nice piece of would. Hopefully I will do it justice. Brian - getting there. I believe it is possible to finish this slab without sanding, and I may well accomplish it with help from a cabinet scraper. The grain around the knots is a challenge. There are splits lengthwise down the middle of the bark side of this board (see picture below). They are not in a straight line nor do they go through the board but I assume they will eventually. I am planning to wrap this slab with Walnut as I need to widen it a little and I think the harder wood will give the edge some protection. I was thinking about using the Walnut to make butterflies which I have never tried before but I thought would be fun. I wish I could figure out why punctuation and paragraph spacing does not work.
    Attached Images Attached Images
    Regards,

    Kris

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