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Shellac: soft when cured

Discussion in 'Finely Finished' started by sansa, Feb 11, 2014.

  1. sansa

    sansa Tele-Meister

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    Hi everyone. I recently used some non-dewaxed shellac and the result is been a soft laque. If I touch it with my nail it shows a mark that disappear in a minute...
    What's the deal??

    I tried to give some explainations:

    1)could be the fact that the shellac has wax so it doesn't allow a good polymerization

    2)could be the fact that I didn't waited sufficiently between coats (even if was dry at touch...) since there are about 20 coats!

    3)the shellac is gone bad; the majority of sellers here in italy don't know that shellac has a life period actually. they sohuld put an expiration date to be onests!

    thank you all very kindly
     
  2. Mike Simpson

    Mike Simpson Doctor of Teleocity

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    Are you using something premixed or are you mixing a fresh mixture of shellac flakes and alcohol?
     
  3. sansa

    sansa Tele-Meister

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    obviously I'm using flakes. the shellac is non-dewaxed
     
  4. trippercaster

    trippercaster Tele-Meister

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    I'm fairly certain you can buy dewaxed shellac flakes.
     
  5. sacizob

    sacizob Friend of Leo's

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    Sarcastic answer for someone seeking help.
     
  6. Mongo Park

    Mongo Park Tele-Afflicted

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    Google's your friend, dewaxed shellac flakes are to be had.
    So skip the question if it is blond or not.
    So I will ask the next one do you have something under the shellac, or is it on bare wood.
    How thick is the shellac to be dentable and bounce back.
    Cheers Ron
     
  7. sansa

    sansa Tele-Meister

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    I don't see what you mean...
    I think you are completely out of my question!
     
  8. sansa

    sansa Tele-Meister

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    I absolutely don't want to be sarcastic. I was just saying that it's impossible to find pre-mixed non de-waxed shellac. I never seen a brand that sells it...

    You can find this kind of pre-mixed shellac on a specific store (that is the same thing to do it on my own) but there's no way to find that from a factory
     
  9. Mike Simpson

    Mike Simpson Doctor of Teleocity

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    I have used shellac from flakes many times with no problems. I have used dewaxed so I could spray lacquer over it.

    Perhaps it was not cut with enough solvent?
     
  10. chrisgblues

    chrisgblues Tele-Afflicted

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    I used to work in a paint store and the owner was an expert in all paints including shellac and I specifically remember him saying that shellac should be used quickly and the longer it sits on the shelf the softer it will cure, in fact if it's very old it may never harden. This might be the answer to your problem. It's easy to strip with alcohol, and do it again with FRESH flakes.

    JMHO.
     
  11. chrisgblues

    chrisgblues Tele-Afflicted

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    Also shellac cans have expiry dates in my country...usually on the bottom of the can. I'm not sure about Italy...but they SHOULD have expiry dates.
     
  12. sansa

    sansa Tele-Meister

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    I use flakes not cans... I was thinking about an expiration date in the flakes envelope...



    Did you remember what's the way it looks like when it's old?

    I read here http://www.shellacfinishes.com/Contact_and_FAQ.html and I saw it with my own eyes that when it's old it becomes a gelatinous mass when you dilute in alcohol... THAT IS NOT THE CASE WITH MY NON DE-WAXED SHELLAC

    The result in my piece of wood is that it hardens but not enough.. It's like it can never cure and stays soft....
     
  13. Tom Pettingill

    Tom Pettingill Tele-Holic

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    Nothing wrong with non dewaxed shellac as long as the only thing going over the top of it is more shellac. The only time you have to have dewaxed is when using under other finishes.

    Old flake does not dissolve very well. If it dissolved, its fine.

    Fresh and higher test / proof grades of alcohol are preferred for mixing. Open / exposed old alcohol can pull a significant amount of moisture from the air. Water in the mix can and does slow drying and if trapped, will cause a softer surface.

    That certainly could be an issue.
     
  14. sansa

    sansa Tele-Meister

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    Thank you very much Mr Pettingill.
    I'd think of these two last sentences because I'm sure I've been careful with the other points you described above...

    It surely can be the non-sufficient time between coats because the soft part is one that I made really quick.
    It can be also the moisture 'cause many times I cleaned the surface from sanding dust with a humid cloth immediately before giving an other coat of shellac (and without waiting it was completely dry now I suppose) !

    HOWEVER: what's really important to me is the assurance that non de-waxed shellac DO NOT causes these inconveniences and hardens well also in numerous coats!
    Are you sure about this Mr Pettingil?

    PS: I said it's really very hard to find de-waxed shellac here and so I'd have to order it in great quantities to afford that (which is always a bad idea)...
     
  15. Keyser Soze

    Keyser Soze Tele-Holic

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    Shellac is a strictly evaporative finish. It does not polymerize after drying.

    Like Tom noted, drying time can be extensive if multiple layers are laid down quickly. This is entirely analogous to lacquer drying times, except that alcohol isn't nearly as volatile as lacquer thinner, so actual drying times can be even longer.

    Non-dewaxed shellac has very little if anything to do with the final hardness of the film, I've got bags of shellac buttons - all non-dewaxed - that are harder than typical bakelite. Ordinary shellac flake I crush in a mortar and pestle prior to dissolving. The buttons require a hammer.

    The downside of non-dewaxed is that the finish tends to be less clear, and adhesion of other topcoats can be problematic. The upside of non-dewaxed is that the surface film tend to be tougher (more resistant to abrasion, and moisture.)
     
  16. sansa

    sansa Tele-Meister

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    That's probably the reason why isn't as hard as bakelite! Many coats don't adhere!
     
  17. R. Stratenstein

    R. Stratenstein Doctor of Teleocity Ad Free Member

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    My guess would be old flakes.
    As TomPettingill said if it dissolved promptly (no longer than overnight at room temperature), it's probably OK.

    If you still have some of it mixed, try putting just one drop on a piece of glass. It should harden quickly at room temperature, certainly be very hard by overnight. If you do this test, and it does harden OK, you've probably just got too many coats on, too quickly, and if you give it more time, it should harden up eventually.
     
  18. Mongo Park

    Mongo Park Tele-Afflicted

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    I keep mine, shellac flakes, in the freezer, which prolongs their usable life.
    If the coats are put down very thin and even then sanding between coats is not needed. If slight imperfections occur a coat heavy in alcohol can smooth things out. One method puts down coats one, heavy with alcohol will remove coats, no need for sanding which will give you a better clearer finish.
    Cheers Ron
     
  19. oldunc

    oldunc Tele-Meister

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    Even French Polishers use abrasives-rottenstone and fine pumice- between coats. Sanding shellac is particularly useful because it remains soluble in alcohol- the sanding dust (which you needn't remove, if you're only sanding shellac) will actually help fill imperfections.
     
  20. sansa

    sansa Tele-Meister

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    Hello, it hardens very nice... So it is not the case... I think it is the fact that I put too much laque in a small time lapse!
     
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