Logs to blanks wet or dry

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  • poolhound
    Veteran Member
    • Mar 2006
    • 3195
    • Phoenix, AZ
    • BT3100

    Logs to blanks wet or dry

    The monsoon season here in Arizona has one bonus in that there are typically a number of downed trees available for the taking. At the weekend I got most of the large logs from a mesquite that was cut up only a couple of days before.

    As many of you know I am brand new to turning so am not quite sure about the whole green vs dry wood scenarios. My question is should I paint the ends of the logs in sealer and leave them for some months or cut them into blanks now?
    Jon

    Phoenix AZ - It's a dry heat
    ________________________________

    We all make mistakes and I should know I've made enough of them
    techzibits.com
  • leehljp
    Just me
    • Dec 2002
    • 8429
    • Tunica, MS
    • BT3000/3100

    #2
    In general, you do, and to be on the safe side I would paint the ends. However with mesquite, it may not be necessary. Mesquite is one wood of very few woods that do not shrink or expand with humidity changes and drying out - which causes cracking / checking.

    Because Mesquite doesn't move as much as most woods, it may not matter wether you cut now or wait. This is my understanding from the book on "Understanding Wood" by Hoadley.
    Last edited by leehljp; 09-02-2015, 02:06 AM.
    Hank Lee

    Experience is what you get when you don't get what you wanted!

    Comment

    • poolhound
      Veteran Member
      • Mar 2006
      • 3195
      • Phoenix, AZ
      • BT3100

      #3
      Thanks Hank,

      To clarify you say "you do" but do you mean a) You do - leave as logs with sealed ends for some time or b) You do - cut blanks but still seal the end grain?

      Originally posted by leehljp
      In general, you do, and to be on the safe side I would paint the ends.
      Good to hear that Mesquite is a stable wood as we have lots of it around here :-)
      Jon

      Phoenix AZ - It's a dry heat
      ________________________________

      We all make mistakes and I should know I've made enough of them
      techzibits.com

      Comment

      • leehljp
        Just me
        • Dec 2002
        • 8429
        • Tunica, MS
        • BT3000/3100

        #4
        Sorry, It was around 2 am when I posted that. I did not make it real clear. I should have said "Normally, you DO need to coat/paint the ends on fresh cut woods . Even with Mesquite that doesn't move with humidity changes (outside environment or inside the wood itself), it will not hurt it to paint it, but not totally necessary, from what I have read.

        The book that I referenced, gives the movement with humidity changes - wet/dry content - length wise, thickness wise and width wise. Mesquite has very little. It is the movement with drying out that causes checking and cracking.

        ON the other hand, thinking about what you want to do:
        IF I were making lumber/boards, I probably would not paint the ends. An inch or two of end cut-off would not hurt in this situation.
        However, with bowls, even a 1/4 inch checking can affect the bowl cuts, if nothing else than to make the bowl a bit smaller than originally wished.

        For this reason, I think I would paint it to be on the safe side.

        One method that some turners use is to cut the blanks to size and put them in paper bags, (one per bag), tie up the end of the bag and let them air dry in the bag. That slows down rapid humidity loss, preventing most/any checking.
        Last edited by leehljp; 09-02-2015, 10:14 AM.
        Hank Lee

        Experience is what you get when you don't get what you wanted!

        Comment

        • Bill in Buena Park
          Veteran Member
          • Nov 2007
          • 1865
          • Buena Park, CA
          • CM 21829

          #5
          Jon,
          In addition to what Hank said, you can find some good videos on processing logs into blanks, and many turners (myself included) will process when the wood is fresh by removing the pith and sealing the ends to reduce checking. Some will check anyway, so leave a little extra length. I've primarily used AnchorSeal and AnchorSealII, but I hear latex paint or wax will also work. I've had some logs start checking within days of being cut if not processed, and like to split through within a week. Obviously depends on the wood.
          Bill in Buena Park

          Comment

          • capncarl
            Veteran Member
            • Jan 2007
            • 3564
            • Leesburg Georgia USA
            • SawStop CTS

            #6
            A non-turner question thrown in here. If a log is going to check, why not go ahead and turn it and reduce the amount of wood? Would a green wood bowl check as bad as a log?
            capncarl

            Comment

            • Bill in Buena Park
              Veteran Member
              • Nov 2007
              • 1865
              • Buena Park, CA
              • CM 21829

              #7
              Cap,
              I'll try to give this a shot. The internal stresses in a log, which wants to shrink radially as it dries, creates the checking radiating outward from the pith. So if you turn something from the log that still has the pith, it will still contain the same stresses and likely crack in the same way as it dries. So turners of green blanks generally remove the pith. Using blanks without pith, when turned green, the bowl will still "move" based on the stresses as it dries, often deforming. Twice turning (rough turning first, drying in a controlled environment, then finish turning) helps work around this, and reduce the chance of cracking in the finished bowl. Some who turn to finish when wet want/prize the resulting deformation, and if thin enough, also can reduce chance of cracking. Depending on grain orientation in the turned bowl, it may elongate or curl along the edges.
              Last edited by Bill in Buena Park; 09-03-2015, 12:52 AM.
              Bill in Buena Park

              Comment

              • leehljp
                Just me
                • Dec 2002
                • 8429
                • Tunica, MS
                • BT3000/3100

                #8
                Bill brought up some great points.

                Different woods respond differently, and, different turners have their own ways of dealing with each. Because Mesquite was mentioned, I responded that mesquite doesn't fit the norm for the majority of woods.

                I have not turned many bowls and the last ones that I did turn - was when I was still in Japan before 2011. I am not the expert on bowls from experience, but because of problems with unexpected wood movement on two beautiful tables (one cherry [movement] and one red oak [cracking]) back in the early 80's, I read everything I could on the subject when possible. Hoadley's book was the most comprehensive. That was my "go to" book when making something. It does not cover as much a variety of woods that I used in making pens, or exotic woods from outside the Americas. And reading bowl turners comments, I focused on the aspect of wood movement and how it affected the turnings.

                There are two problems that green wood presents: Movement - shrinking or expanding; cracking - like checking. There is a difference.

                That said, bowl turners generally go three different routes:
                1. Fully dried (less than 5% I think) wood that does not move. Usually a finish is applied inside and out to prevent or reduce humidity changes.
                2. Wet turning just turns smoother in most varieties. But as mentioned, it warps and or checks when drying. So, turn it to rough shape. If one wants a 1/4 inch thick wall, the turner will turn it to about 1 or 1 1/4 inch wall (or thicker) depending on the size and then dry it slowly over months. This leaves enough wall to deform and still have a perfectly round bowl/vase left inside.
                3. As mentioned above, the warping effect of drying is desired in some cases. An experienced turner will know which woods will warp more than crack. Additives can change this:

                There are variations on these, including placing a green or dry bowl in liquids, liquid waxes, oils etc to replace the moisture content in the wood. This action usually goes to reduce movement and more than anything else, prevent Cracking.

                Movement/warping can be good, cracking generally is not. Cracking on large boards do give an opportunity for artistic expression as in using "butterfly" ties or "fill ins" like turquoise. Powdered/ground turquoise and other fillers works fairly well on bowls to some extent.

                One warning, you do not want to turn a bowl that is cracked. Dangerous. But I have read (and seen results) of an extremely experienced turner who was very cautious in his turning. Again, this is very dangerous.
                Hank Lee

                Experience is what you get when you don't get what you wanted!

                Comment

                • capncarl
                  Veteran Member
                  • Jan 2007
                  • 3564
                  • Leesburg Georgia USA
                  • SawStop CTS

                  #9
                  Last week I spent several hours in The Alaska Bowl Co. In Fairbanks watching them turn several of their birch bowls. This was the basis of my uneducated question. They have a system where they turn a whole family of bowls out of one large blank. I didn't ask them about their curing process, nor would I have expected them to tell me. What I saw looked like they used freeh cut logs. The store lady there said that after they cut these bowls they are kept grouped in families and carried upstairs until they are ready for finishing. What she said could be taken several ways, when they, meaning the bowls are ready for finishing or when they, the bowl finishing crew is ready!
                  Their family cutting process was interesting but i won't butt on on this thread with that.
                  capncarl

                  Comment

                  • Bill in Buena Park
                    Veteran Member
                    • Nov 2007
                    • 1865
                    • Buena Park, CA
                    • CM 21829

                    #10
                    Cap, I'm pretty sure that as production turners they use a bowl coring tool to produce the families. This allows for several bowls of progressively smaller sizes to be made from the same large bowl blank and reduce waste. These are done green and left thick as Hank described above so they can be finish turned when they are dried and stopped moving. Reed Gray aka "Robo Hippy" has some great YouTube videos showing how this is done.
                    Bill in Buena Park

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