Natural Edge Bark Question

Discussion in 'Woodturning Discussion Forum' started by Jamie Straw, Oct 28, 2017.

  1. Jamie Straw

    Jamie Straw

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    OK, so I've throw a natural-edge maple bowl back on the lathe for second turning. The bark had a few tiny gaps where it joined the tree, so I dropped some thin CA in, worked great while I was refining the outside. The strong temptation is to soak all of the bark in CA. :D Perhaps not? How do you approach and/or treat the bark edge as you're turning?
     
  2. Lamar Wright

    Lamar Wright

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    I've seen videos where turners have soaked all the bark on a bowl to save the bark when turning. I have not tried a natural edge bowl yet, but I would not hesitate to try it.
     
  3. john lucas

    john lucas

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    I often soak the cambium layer with thin CA to help hold the bark on. I have had bowls hold thier bark for many years and a few where the bark separated after a few years. Haven't done enough to know why one does and one doesn't. CA certainly won't hurt. If there is any loose bark to start with I will glue it back on with CA. I just wrote an article for More Woodturning magazine on painting, burning and other methods of dealing with natural edge bowls that lose the bark. Don't know when it will come out but think it might be in the next issue or two.
     
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  4. hockenbery

    hockenbery AAW Advisor Staff Member

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    I only turn NE bowls once. I usually remove the bark. It is more work as something has to be done to finish the places where the bark was but the result is a functional bowl that people can use.

    If I want to keep the bark I use thin CA glue when the bowl comes off the lathe.
    Using gravity to keep the CA off the wood ( CA becomes an imperfection in the finish)
    I run CA around the inside surface of the bark and around the outside surface of the bark.
    I want the CA to wet the bark and penetrate the line where the bark meets the wood.

    On a once turned bowl this is essential to keep the bark from shrinking more than the
    Wood. Ca saturated bark will shrink a little less than wood.
    In a couple of days when the bowl is dry I sand the bark level with the wood.
     
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  5. Bill Boehme

    Bill Boehme Administrator Staff Member

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    If you have the tiny capillary tubes like Starbond includes with their CA glue that is very good for applying a tiny amount of their super thin CA right along the cambium layer ... the layer that is the boundary between the bark and sapwood. It soaks into the wood and especially the bark without being noticeable. You can do this in stages ... when you first start the final turning, but still have a lot of wood to remove and once or twice before the finishing cuts at the rim. By turning away any CA that remains on the surface it won't be noticeable after making the final cuts. If you're turning the bowl in stages then you will need to work the rim as you progress down.

    Sometimes, bark being sponge-like will have some moisture ... enough to make the CA go high-order (rapid exothermic chemical reaction) with a lot of foaming and fuming. You're probably familiar with that, but be careful and don't go overboard and sop the bark with CA. I have a love/hate relationship with CA. I never fail to get it where I don't want it. I glue my hand to the work, I glue my fingers together, I glue my hands to my jeans, I glue my shoe to the floor ... you name it and I've done it. I'm getting better about it, but still having mishaps. I now always go outdoors and have plenty of paper towels and rubber gloves and face shield.
     
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  6. Fred Belknap

    Fred Belknap

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    I put thin CA on my NE bowls after the final turning but before the final sanding. I like to leave it over night to do the final sanding but it works ok after a hour or so. I put the CA on the inside of the bowl while it is attached to the lathe, but turn it upside down with the chuck still on to do the outside. I have found that wood that has laid on the ground will almost always come loose. When I cut a tree I block it up off the ground if I am going to leave it more than one or two days. Don't get Anchorseal on the bark, it is hard to get off. I really like NE bows with the bark but it requires a little extra work. It will never be as strong as the wood but will last for years on decorative bowl. Don't drop it or pick it up directly by the bark just to be safe. If a piece breaks off it can be glued back on.
     
  7. Gerald Lawrence

    Gerald Lawrence

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    I like turning NE but there are some maybes in the process. Best to use wood cut after the sap falls. Yes glue the cambium layer after first cuts, also save some of the bark you turn off to patch holes in the bark. After I had done a few and realized there is no reason whatsoever to twice turn a NE bowl. Turn to finish and if the bowl warps the majority of people will never know it. You may mave to sand after the bowl dries but that should be easy to put the bowl over the chuck with a pad inside and bring up the tailstock with soft touch on it. I like to cut the bark with a parting tool to start and get less bark loss .
     
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  8. Paul Gilbert

    Paul Gilbert

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    Gerald -
    I like the idea of using a parting tool to start the cut on the rim of a natural edge bowl, but can't whap my imagination around how to do this on bowls with a lot of difference between the high and low profile of the edge. On most of the natural edge bowls that I have turned, this is a cut with a lot of air in it. Do you use some technique to sneak up on it, or just go after it like you were using a gouge.
     
  9. Donna Banfield

    Donna Banfield

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    Gerald Lawrence talks about turning natural edge bowls from trees after the sap falls. Another way of putting it - the best success of turning a NE bowl and having bark stay on is to cut/harvest the tree in the dead of winter. In the northeast US, that is January/February. Turn the bowl shortly after harvesting, and turn it once to final thickness. Thin CA glue can be used on the cambium layer, to ensure good adhesion to the wood.

    I use an air compressor to blow as much moisture out of the wood to allow sanding (the wall thickness has to be 1/4" or less for this to work). A day or two later it might need some more hand-sanding with 220-400 if moisture remained, causing the grain to raise. Then finish as usual.
     
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  10. Gerald Lawrence

    Gerald Lawrence

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    Just use it like any parting cut but watch the angle depending on the final shape of the bowl. Also with so much air you have to hold the tool steady and advance gradually and evenly.Oh and go straight in with the tool since it is not a final cut .
     
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  11. hockenbery

    hockenbery AAW Advisor Staff Member

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    The partng tool can be a big help by both defining the inside edge and providing a place for the bevel of the gouge to ride.

    We use that technique in kids classes where their first turning is a top.
    They can roll the gouge on the wood to cut the the handle side of the top because there is lots of wood to rest the bevel on as they pick up the cut. Cutting the other side the rim gets turned to almost a point so they have difficulty picking up the cut and have a high risk of chewing up the edge of the top. Making a a shallow parting cut defines the thickness of the top rim and provides a defined place for the gouge bevel to ride and they don’t ruin the edge.

    On NE bowls the interupted cut is one if the more difficult techniques to master.
    Beginning the hollowing cut can easily chew up the bark and break off a strip of bark which may ruin to the rim.
    I have a lot of success using a gouge but I cut the wall an inch wide to start and use a bevel riding cut. I then sneak up on the finial wall thickness of 3/16” or whatever always cutting the bark so that it is supported b the wood underneath so it cuts cleanly.

    Using the parting tool as a scraper parallel to the outside wall cuts the bark fairly cleanly and gives a nice spot for the gouge bevel to rest to pick up the cut. It is a technique that works well for quite a few people. The parting cut is usually about a 1/2” or a little less. The parting cut has to be straight and the wall is usually curved.

    I think I get a cleaner surface using a push cut with the gouge and I use an advanced cut that takes some time to master that makes and cleaner surface than the push cut..

    In central Florida we don’t have the luxury of dormant trees. Most deciduous trees are semi evergreen and keep their leaves all year. Elms, sweet gum, Maples May lose their leave for a few weeks before leafing out. CA will keep the bark most of the time.
     
    Last edited: Oct 29, 2017
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  12. musky

    musky

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    If you have to drop a tree when the sap is still flowing, and you would like a little better odds at keeping the bark on when turning, try leaving the branches, and leaves on the dropped tree for a couple of weeks before cutting up the tree. They will continue to pull moisture out of the tree for awhile. This will help somewhat at keeping the bark on summer cut wood, but still not be as good as a tree cut in the winter.
     
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  13. olaf Vogel

    olaf Vogel

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    I always start from the outside, go in, using a Thompson 1/2 gouge with a very sharp grind on it.
    Keep it a very high angle, almost perpendicular to the piece, so thats just slicing off small cuts.
    Then sneak in VERY slowly. The initial cut is the hardest, cuz you can't really see when the chisel first contacts. Its all by feel.

    http://www.olafvogel.com/platters1.html
    The one at the bottom was a challenge.

    Takes some practice to be really steady and I only do this with green wood.
    I usually do larger pieces and make no attempt to try to turn them twice.

    A few platters were very large, all cross grain, NE. They distorted a lot while drying. Re-turning them was not an option. So I just power sanded them into finished form. Does a great job of keeping the bark on.

    As for soaking in CA, I find that very expensive. So only use if for repairs. Depending on the species, the bark can shrink a LOT. Manitoba maple does.

    When its dry, I soak the bark in shellac. Cheaper and works.
     

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