Restoring a crazed (from the sun) lacquer finish.

Discussion in 'Clock Case Restoration and Repair' started by kinsler33, Mar 10, 2019.

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  1. kinsler33

    kinsler33 Registered User

    Aug 17, 2014
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    It's a Sessions tambour clock with a label that sez "Purchased 1924" but much of the intervening time must have been in the bright sunlight. That's because all of the lacquer finish seems to have been deeply crazed by the sun. I've repolished the bezel and re-sivered the dial, but the case's fine glossy finish is but a memory, afflicted with fine cracks that have swelled into a kind of matte finish. I've been advised to try this stuff,
    but I don't know if it would help more than just brushing the finish down with lacquer thinner, which has also been suggested.

    Any suggestions? Condemnations?

    M Kinsler
     
  2. glenhead

    glenhead Registered User
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    The finish is most likely shellac, not lacquer. That's good news for you.

    Start by cleaning the whole danged thing with mineral spirits on a cotton cloth (like an old t-shirt, not terrycloth), either spritzed/misted with a spray bottle or by dampening the cloth. (Mineral spirits don't harm a shellac finish - wrong solvent.) That will remove accumulated yarg. You'll know it's clean-clean when the cloth quits picking up yarg.

    The solvent for shellac is alcohol. The species of alcohol doesn't really matter in this instance. That said, the experts recommend Behkol, which is a very clean denatured alcohol sold specifically for wood finishing. (Of course that means it's many times the cost of off-the-shelf denatured alcohol - your money, your choice.) Everclear also works nicely. You can try another strip of t-shirt dampened with alcohol and see if that will cause the shellac to relax? soften? melt? to the point the crazing goes away. You *can* use a brush, but doing it by hand lets you feel what's going on. If that works, then a couple more layers of shellac will bring the finish back to "nice". If that doesn't work, then you'll need to decide if you're going to strip and refinish or just apply more layers of shellac. The cool thing about shellac is that subsequent layers melt previous layers and bond with them. You can find several methods for finishing a shellac finish, so I'll leave it at that.

    Hope that gets you rolling.

    Glen
     
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  3. kinsler33

    kinsler33 Registered User

    Aug 17, 2014
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    Thank you.

    As it happens, the finish is lacquer of some sort, for neither mineral spirits nor alcohol from my trusty spray bottle softens it. And so I was going to try consolidating the finish with lacquer thinner (carefully applied with a brush) when the owner of the clock called to ask if it was done, and when I mentioned the finish he said that he wanted to do that part himself.

    So that, uh, finishes that, at least for the time being. But I will try this method on other finishes, and thanks again.

    Mark Kinsler
     
  4. Bruce Alexander

    Bruce Alexander Registered User
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    #4 Bruce Alexander, Mar 12, 2019
    Last edited: Mar 12, 2019
    Hi Mark,
    You really have to watch out for those "crazed" finishes! :chuckling:
    I trust that you have noticed the Shellac Tutorial Permanent Thread at the top of the forum. It's more along the line of mixing and applying Shellac rather than recovering a Shellac Finish.
    If you didn't have a chance to try Lacquer Thinner, your customer's clock could also be finished with some type of Varnish. That can be some pretty tough stuff to deal with.
    Regarding the Howard product, I have limited experience/success with it. I think it's best when you're dealing with finished wood that has lost most or all of its protective coating. All moot points now as it's not your problem. Count your Blessings. Dealing with a clock's finish can be more time consuming than overhauling its movement.
    Regards,
    Bruce
     
  5. kinsler33

    kinsler33 Registered User

    Aug 17, 2014
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    Thank you, and while I remain curious about the possibilities of renewing old clock finishes I'm glad I didn't have to do this one. I've noticed that I'm becoming more interested in the appearance of clocks, though I still like to work on movements.

    A few of my customers worry that even cleaning up the case of their old treasures will lower the value. I generally have to respond (gently) that the cleaning/polishing restrictions apply to old coins, not clocks, _and_ that old clocks aren't worth a whole lot anymore, anyway.

    I do wonder how much of my repair business is driven by customers who think their old Ingraham is worth thousands of dollars.

    M Kinsler
     

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