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Thread: Resanding Oil Finish

  1. #1
    Join Date
    Mar 2015
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    Warsaw, Missouri
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    65

    Resanding Oil Finish

    I'm reworking some bowls and other turned items left over from a while ago before I appreciated the importance of a good sanding regimen.
    I have some items that were finished with WDO, and in a raking light now I see some rather profound scratchs - like, "return to 100 grit" profound.

    Even though these are well-dried items, when I started trying to sand back I mostly generated gummy mess or at best instantly clogged paper. Any tricks for sanding back an oil finish??

  2. #2
    Join Date
    Mar 2003
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    SE PA - Central Bucks County
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    Perhaps you need to strip the "oil" finish first chemically...if it's gumming up like you describe, sanding it off is going to be difficult.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
    Join Date
    Feb 2008
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    E TN, near Knoxville
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    8,246
    Quote Originally Posted by John Nordyke View Post
    I'm reworking some bowls and other turned items left over from a while ago before I appreciated the importance of a good sanding regimen.
    I have some items that were finished with WDO, and in a raking light now I see some rather profound scratchs - like, "return to 100 grit" profound.

    Even though these are well-dried items, when I started trying to sand back I mostly generated gummy mess or at best instantly clogged paper. Any tricks for sanding back an oil finish??
    For sanding after the oil dries I always wet sand with the oil. On extreme cases I might use hand scrapers first to remove the scratch then wet sand.

    I do several things to help me see the scratches while sanding:

    - I always use a glancing light while working - I prefer multiple small diameter bulbs in swing-arm or gooseneck fixtures. I position them as needed to better see and judge both the curvature while turning and later, any turning defects and sanding scratches. (It's surprising how much this helps to see turning defects such as inflection points in what's supposed to be a continuous curve.)

    - I do most of my sanding with the chuck removed from the lathe and mounted on a carving/finishing post. I can tilt and angle it in different directions, almost like holding it in the hand. This makes it far easier to see defects than when bending over and looking while rotating the piece on the lathe. The finishing post also lets me angle the piece is various directions. This is what I use:
    carving_stand_IMG_20171111_162052_024.jpg

    - Before moving to the next grit I sand at 90-deg to the direction I just sanded. This will leave minor scratches across the grain/figure which I then remove with the next finer grit. I figure that if I can't easily remove a 400 scratch with 600 paper it's probably a deeper scratch from a previous grit.

    - After sanding with a grit, I wet the surface with naphtha on a piece of paper towel. Naphtha dries rapidly and leaves no residue. The naphta does several things - while soaking wet it lets me see what the color will be like and how well the figure will "pop" when I apply oil. While wet it makes any turning defects very obvious. But more importantly, as the surface liquid starts to evaporate and before it dries there is a short time where any remaining scratches are far more visible, especially in glancing light. I may reapply several times while scratch hunting. Note that I'm looking for deeper scratches I missed earlier or, gasp, tool marks.

    BTW, I've mentioned this before but I don't power sand with coarse grits. Eliminating this helps a lot. I smooth with negative rake scrapers while spinning then use hand scrapers to remove any tool marks. This usually lets me start sanding with 220 or finer paper so I don't have to deal with scratches from coarser girts. If I do power sand it's gently with a small pneumatic random orbital sander with fine grits.

    JKJ
    Last edited by John K Jordan; 08-23-2019 at 9:46 PM.

  4. #4
    Join Date
    Mar 2015
    Location
    Warsaw, Missouri
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    65
    Thanks for the info, John. I have a good finishing schedule now - good in terms of final results. Always looking to reduce time/effort because I'm at that crossroads I imagine many face - trying to balance the cost in terms of time/effort on finishing vs what the market will bear for any given piece.

  5. #5
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
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    8,246
    Quote Originally Posted by John Nordyke View Post
    ... trying to balance the cost in terms of time/effort on finishing vs what the market will bear for any given piece.
    I've got that balance figured out buy my method may not suit everyone: in general I don't sell things but give them away. Then I can spend as many hours as I want!

    I've had a lot of offers to buy things but the only things I've ever sold were thin spindles - "magic" wands, conductor's batons, riders crops.

    JKJ

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