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Thread: Fixing ding in Tru Oil finish?

  1. #1
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    Default Fixing ding in Tru Oil finish?

    I was happy with the Tru Oil finish I did on my mahogany uke. However, when installing the bridge, I put a small ding in the finish. Maybe 1/8" around.

    I thought about different ways to fix it:

    a) Apply TO with a small artist brush, then wipe it off. Let dry and repeat until looks good.
    b) Mask around the ding with tape, sand it and apply TO coats until it looks good.
    c) Sand a larger area w/o tape apply TO coats until it looks good.

    Any tips?

    Thanks,
    Ralph
    1984 Flatiron A5Jr; Collings MT; Built an F-style kit
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  2. #2

    Default Re: Fixing ding in Tru Oil finish?

    Tru-Oil takes a lot of coats to build up significant thickness. And when it does, if we're talking about a thickness more than a piece of paper, you're going to need a long time (maybe months), or lots of UV light, to cure it. When it does fully cure, it will shrink a bit.
    Personally, I would either sand it back to wood in the area and re-finish, or fill with a drop of CA and scrape flush, then re-coat.

  3. #3
    Adrian Minarovic
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    Default Re: Fixing ding in Tru Oil finish?

    CA is much harder than the finish and it will age differently so I would stay away from that. Perhaps tiny bit of very careful steaming of the dent to get it level followed with tiny drops/wipes to fill any damaged surface (let cure and finely sand) and finally one wipe on whole surface and buff.
    Look up frets.com for the steaming of dents.
    Adrian

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    Default Re: Fixing ding in Tru Oil finish?


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    Default Re: Fixing ding in Tru Oil finish?

    +1 on steaming. You can raise a dent by placing a wet towel or paper towel over the dent and carefully steam with a soldering iron. I use a pencil. Short quick touching of the exact spot and change the wet towel each time. You will be surprised at how much you can uncompress (so to speak) the dent.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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    Default Re: Fixing ding in Tru Oil finish?

    Thanks for the replies. Don't really have a dent in the wood. Only a chip in the finish. I think I'll try the "tiny drop/wipe" with TO method and see how it works.
    Ralph
    1984 Flatiron A5Jr; Collings MT; Built an F-style kit
    HogTimeMusic.com // Songs on Bandcamp.com
    "What's Time to a Hog?"

  7. #7

    Default Re: Fixing ding in Tru Oil finish?

    No problems

    Try this one then

    http://www.mirwa.com.au/HTS_Repair_Lacquer_Chips.html

    Steve

  8. #8
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    Default Re: Fixing ding in Tru Oil finish?

    I'm really not sure Steve's approach would work. Sure, on lacquer that's great. But this isn't lacquer. Tru Oil is linseed oil with mineral spirits and some other oils. It just won't build up like lacquer. That's one of the advantages of lacquer, it's reoaiability, and a disadvantage of Tru Oil.

    You could try a drop fill with shellac. It will build up and would probably stick to the Tru Oil, which many things wouldn't. It should be a thick cut of shellac, or put some in an open jar and let it evaporate some to a thicker working consistency so it will stay where you put it. Then build it up higher than the surrounding surface, then use a single edge razor blade ( with Scotch tape over the cutting edge except for 1 spot the exact size of the ding. This protects the surrounding finish) to scape the repair down. Then spot sand down until level and the gloss you want. Maybe gradually down to Micro Mesh 4000 to match the sheen of Tru Oil. Or go even finer if you please. You can rub down the entire top to the same sheen to help hide it, and at that point one or two additional coats of Tru Oil over the whole top may improve things even more. I highly doubt the repair will ever be completely invisible no matter what you do. Hopefully you made this instrument for your own use and not to sell. Good luck?
    Don

    2016 Weber Custom Bitterroot F
    2011 Weber Bitterroot A
    1974 Martin Style A

  9. #9

    Default Re: Fixing ding in Tru Oil finish?

    I've been having excellent luck with Gluboost Fill 'n' Finish products. If you use their accelerator, it cuts cycle time way down. That and a stack of Micromesh pads should get you where you want to be. A bottle of thin weight, a bottle of thick, and a can of accelerator is about 50 bucks.

    http://store.gluboost.com/fill-n-fin...witness-lines/

    ------------------
    Jonathan Ward

  10. #10
    Registered User Wes Brandt's Avatar
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    Default Re: Fixing ding in Tru Oil finish?

    I've used oil based varnish for touchup by pouring several drops in a small jar lid, in a warm area and letting the solvents evaporate, or warming it a bit with a heat gun on low to drive off the solvents quickly, so you end up with a very thick version of the original finish that is still wet… then use a tiny brush or plastic toothpick to apply only as much as you need to fill the dent and a little extra for shrinkage, watch out for bubbles …it will take a while to dry to the touch and then leave it for a week to let it thoroughly dry and then level

    This works for very small dings, and I'm lately using Waterlox oil varnish which dries fast at higher room temperatures. It should work for true oil it just may take more time to drive all the solvents out to thicken it.
    Last edited by Wes Brandt; Mar-25-2017 at 11:03am.
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    Default Re: Fixing ding in Tru Oil finish?

    Quote Originally Posted by Wes Brandt View Post
    I've used oil based varnish for touchup by pouring several drops in a small jar lid, in a warm area and letting the solvents evaporate, or warming it a bit with a heat gun on low to drive off the solvents quickly, so you end up with a very thick version of the original finish that is still wet… then use a tiny brush or plastic toothpick to apply only as much as you need to fill the dent and a little extra for shrinkage, watch out for bubbles …it will take a while to dry to the touch and then leave it for a week to let it thoroughly dry and then level

    This works for very small dings, and I'm lately using Waterlox oil varnish which dries fast at higher room temperatures. It should work for true oil it just may take more time to drive all the solvents out to thicken it.
    Do you end up with witness lines Wes? I've never had success touching up oil varnish without them.

  12. #12
    Registered User Wes Brandt's Avatar
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    Default Re: Fixing ding in Tru Oil finish?

    I'm only doing this with small dings and I don't go for mirror finishes anyway… you should sand a tiny bit with something like 1500 grit so that everywhere the thick varnish touches is not shiny.

    I make my own polish …a paste with tripoli powder and cooked linseed or walnut oil, It can make it very shiny but not total mirror shiny ...but with oil varnishes, somehow can make witness lines disappear… polish it once then several days later more gently. Your not leaving any oil on the surface, wipe it clean with a clean cloth. If this is an older finish then you may have more trouble.

    I also use the thickened varnish to drop fill during varnishing and it "becomes one" with the following coats
    WesBrandtLuthier.com
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    Registered User Frank Ford's Avatar
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    Default Re: Fixing ding in Tru Oil finish?

    I'd take my time, and do it as a drop-fill. Tru-oil hardens by oxidation, and it helps to do thin layers rather than a big glob, so I'd dip a toothpick in the oil, and place a tiny drop in the hole, smear it around a bit, let it harden for a few days, and repeat until the fill is sufficiently thick to scrape it gently level. Then a bit of fine wet sanding to even things out in the immediate area followed by a light wipe with more oil to blend to surrounding finish.

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  16. #14
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    Default Re: Fixing ding in Tru Oil finish?

    There you have it! Frank's answer would be the definitive answer. He is absolutely right about how long Tru Oil takes to "dry". Truth be told, it doesn't really dry at all. The oxygen exposure causes it to self polymerize. So I didn't think it was possible to build up Tru Oil, but it seems you can. It just takes a really long time.
    Don

    2016 Weber Custom Bitterroot F
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    1974 Martin Style A

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    Default Re: Fixing ding in Tru Oil finish?

    Thanks for the additional replies. I put a drop of Tru Oil in the ding and wiped the area. The next day I could hardly find the spot to add more TO.

    My customer (7 year old granddaughter) won't notice the defects that I see. Additionally, after a few months of use there will probably be many more dings than when delivered.
    Ralph
    1984 Flatiron A5Jr; Collings MT; Built an F-style kit
    HogTimeMusic.com // Songs on Bandcamp.com
    "What's Time to a Hog?"

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