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Aggravated with cracks

Discussion in 'Woodturning Discussion Forum' started by John Hicks, Jun 27, 2020.

  1. John Hicks

    John Hicks

    Jan 23, 2020
    Hoodsport, Washington
    I have watched countless videos and read many articles on preparing wood blanks from wet logs. I have yet to have a successful blank of cherry that hasn't cracked to pieces a few weeks after slabbing and sealing. I had this cherry tree, and cut, slabbed, then cut into circles, then sealed several only on the end grain, and several the whole piece. I used anchorseal (2 coats) . I then put them on a shelf in my shop (which I keep at 55% humidity). Every single one of them has cracked so bad in 4-6 weeks, that they are unusable for bowls. The starting moisture level was 30-33% before slabbing. What am I doing wrong?? I keep the logs outside under a tarp, on end using a pallet. I have had similar results with big leaf maple. If I had to buy blanks this size, it would cost a fortune!

    IMG_7320.JPG IMG_7322.JPG
    Mike Amphlett likes this.
  2. hockenbery

    hockenbery AAW Advisor Staff Member

    Apr 27, 2004
    Lakeland, Florida
    Home Page:
    you are drying the wood too fast. You want to keep,it from drying until you turn it.
    Sealing slows the drying but doesn’t stop it. Once cut round it is going to crack if it dries.
    I find it impossible to effectively store a round bowl blank for more than a few days unless I wrap it in plastic and put it in the freezer. Wood dealers coat their blanks in paraffin- too complicated for me,

    for a few days I wrap it with shrink wrap and put it in a plastic bag.

    Wood I won’t turn for a while I leave as a half log at least 4” longer than I will need for the blank and seal the endgrain with anchor seal. Store it outside in the shade.
    When I get ready to turn I cut off 2” from each end which will have end checks then cut my blanks.
    Rough turn the bowls and dry those slowly.
    Last edited: Jun 28, 2020
  3. Greg Norman

    Greg Norman

    Feb 2, 2020
    Germantown, NC
    My experience has shown me this is the worst time of year to saw logs into blanks for turning. The temperature makes them dry way too fast and at least 40% will look like your pic. If I do the exact same thing in December thru February the failure rate is about 4%. If you need to process logs in the summer the best thing to do is rough turn them within a couple of days and put them in a paper bag to slow down the evaporation. If you can’t turn them right away cut the blocks about 6” longer than the diameter of the blank you plan to cut, seal the ends, and sticker them in a unconditioned space like a barn or woodshed, you will still have some checking but not as much. I also wouldn’t saw them round until I was ready to turn them. If you intend to dry them before turning it is best to wait for wintertime to saw them. If you want to rough turn then dry only saw what you can turn in a day or two. I would saw a few and put them in a paper bag with some shavings and turn them as soon as possible then keep them in a bag for a week or two. I would seal them as soon as the surface dries a little.
    Slab 1 was sawed in mid April, 2 was sawed in mid February. This is typical of what I’ve seen over the years. Temperature and humidity have a huge effect on drying lumber and your success will skyrocket if you can do most log processing during the winter months. Ideally I only turn wood that was cut down in December or January. It did take me about ten years to build up enough inventory achieve that though.
    John Hicks likes this.
  4. Mike Johnson

    Mike Johnson

    Jul 26, 2016
    Cutting the short logs down the center at the pith will release some of the internal stresses in the log that create the cracks. As the wood loses moisture content it is shrinking and moving constantly, the more pieces you cut the log into, the less stress and cracking of the wood. When you cut a round log 360 degree in half you end up with a flat 180 degree half pie wet piece, when it is done drying the flat 180 degree piece ends up being about 170 degrees as the log dries and shrinks. When a solid 360 degree log dries it has to relieve the internal stresses in some manner. Slow drying allows the wood a better chance to adjust to internal stresses as the wood moves over time, fast drying increases the internal stress levels which can pull the wood fibers apart internally causing the checking and cracking..
    John Hicks likes this.
  5. Tim Connell

    Tim Connell

    Jan 22, 2018
    Cameron, Illinois
    If I have wood that has to be processed this time of year, I will cut the blanks and throw them in a barrel of water until I can rough turn them. Do need to change the water periodically, or it will really start to stink.

    I had an Apple tree that blew down last June, and I processed it this way. Cut main trunk to lengths I wanted, cut out pith and threw them in barrel. As I had time, bowl blanks were cut and immediately roughed and coated with anchor seal on all surfaces. Spindle blanks were cut at the same time and end grain sealed. Lost very little processing this way in the heat of summer.
    Donovan Bailey and Curtis Fuller like this.
  6. Damon McLaughlin

    Damon McLaughlin

    Jan 16, 2017
    Eastern Washington
    John, I'm on the other side of the state where it can be dry (low humidity). Cherry is a very temperamental wood and prone to cracking. I usually cut the log lengthwise, removing the pitch, and leave the log at least twice as long as the diameter, sometimes longer. When I eventually get to it I can usually get one bowl blank some where in the middle of that piece. But even still, this time of year, the log will split the entire length. And its not just cherry, I find that with most fruit woods here. These days if I get some cherry I'll finish turn it thin and let it warp. If I rough turn it about 50% will crack. I think your 55% humidity in the shop is too low for allowing the wood to dry slowly, based on your pictures the wood is drying too fast.

    One option is if you can keep long logs then just cut off what you need when you need it.
    John Hicks likes this.
  7. Dean


    Jul 17, 2010
    Waco, TX
    John , you need to either core those or rough turn the guts out then seal them up real good. Oak and cherry split easy because the love to Shedd water remove the pith, and get rid of the guts.
    John Hicks and hockenbery like this.
  8. robo hippy

    robo hippy

    Aug 14, 2007
    Eugene, OR
    Well, I haven't experimented much with using rounded to size blanks, but..... I do not consider anchor seal to be a good protector for blanks cut to size. It doesn't seal 100%, which is what you need. I have kept some rounded madrone and apple blanks by just wrapping the outside, making sure that the film wraps an inch or so over the rim, for 6 or so months at a time. The apple blanks were 6 by 12 inch. The madrone blanks were smaller. I have sealed madrone cylinders, 3 inch diameter, with Titebond glue, again, making sure to seal an inch or so down the side as well as the end grain. Won't know how well it works until I turn them down. I have had pieces of madrone that looked fine on the outside, but were shattered on the inside. Madrone is just like that.... I guess if you want to go overboard for protection, use anchor seal or titebond, then use the stretch film over the outside, and again, make sure the sealer wraps over the edge an inch or so. I generally prefer to keep my logs whole and cut as needed rather than prep it out and let it sit. I get more survivor pieces that way.

    Most interesting way of sealing the ends of logs that I have heard of, but haven't tried, was to seal the end with laytex or oil based paint, and who doesn't have several cans of old paint around? BEFORE the paint dries, slap some plastic film on that. The wet paint sticks to the plastic and keeps it in place. The plastic totally seals the end of the log, and again, I would wrap over the ends a bit. Cover with a tarp and keep it off the ground and out of sun light.... I guess the same method would work with anchor seal.

    Other than that, rough turn your blanks. The less mass there is, the less stress you will have in your wood as the moisture levels try to equalize with the local environment. Round over all edges and seal past the edges.....

    robo hippy
    Gerald Lawrence likes this.
  9. Charles Cadenhead

    Charles Cadenhead

    Dec 28, 2019
    Tallahassee, FL
    Don't think of it as aggravated but an opportunity to practice filling voids with epoxy. :)
  10. Larry Copas

    Larry Copas

    Oct 23, 2015
    Springdale, Arkansas
    Home Page:
    I keep it in the log until I'm ready to turn, which I think is the best method.

    Sometimes I do have to cut blanks. I have a roaster oven sitting on a bench filled with paraffin (canning wax). The blank end grain is dipped in the wax or if to big I paint the wax on. Not had much trouble.

    I have a sawmill and have end coated logs with Anchor Seal. I've found it works best if I get the Anchor Seal on the day I buck the log than apply a second layer the next day. I would want to follow the same practice with turning blanks, but never having done it, not sure how good it would work.

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