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Thread: Dewaxed shellac under polyurethane

  1. #1

    Dewaxed shellac under polyurethane

    I understand that dewaxed shellac under polyurethane is safe but does it matter if the polyurethane is oil or water?

    I plan to use the oil and hard maple. Is the basic use of dewaxed shellac under polyurethane for blotching? I've heard that it's also a fast first coat to build up a finish.

    Phil

  2. #2
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    The top coat shouldn't matter over a sealcoat of dewaxed shellac.

    Yes, it will help with blotching but will dramatically alter how the wood stains if you plan on using a stain. Using a water or alcohol soluble dye is an even better solution.

    I would strong suggest looking at an alternate finish if you are using regular home center one part polyurethane. Nearly ever quality non-poly varnish is much easier to use and gives a much better finish.

    Look around here with the search for Waterlox or Behlen's Rockhard.

    Joe
    JC Custom WoodWorks

    For best results, try not to do anything stupid.

    "So this is how liberty dies...with thunderous applause." - Padmé Amidala "Star Wars III: The Revenge of the Sith"

  3. #3
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    Are you planning to stain or color the maple? If so, dye is the way to go, maple will be blotchy with a pigment stain.

    What look and feel do you want when finished?

    What have you built?

    If it's not a floor, or something that will be walked on, then poly is not the best varnish to use. Poly gets all the marketing hype and ad money because it the cheapest varnish to make; thus has the biggest impact on the manufactures' bottom line.

    Either oil based poly or water-borne finishes will not stick to shellac that has not been dewaxed.

    Shellac is a better water vapor barrier than poly. Maple is a close grained wood that will allow most any film finish to build quickly.
    Scott

    Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.

  4. #4
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    Either water based or oil is fine over dewaxed shellac.
    I'm not positive about oil based poly over bare maple as I never tried that, but wb will cause no blotching at all and the wood will look very light for a pretty long time.

  5. #5
    This is for hard maple handles for bread knives, cake knife and butter knife.

    I've used hard maple before for these handles, in the past and for these I'm not staining, I just want to build up a nice gloss build. So if the shellac will reduce a coat or two of poly I'm thinking it's worth it.

    Phil


    Quote Originally Posted by Scott Holmes View Post
    Are you planning to stain or color the maple? If so, dye is the way to go, maple will be blotchy with a pigment stain.

    What look and feel do you want when finished?

    What have you built?

    If it's not a floor, or something that will be walked on, then poly is not the best varnish to use. Poly gets all the marketing hype and ad money because it the cheapest varnish to make; thus has the biggest impact on the manufactures' bottom line.

    Either oil based poly or water-borne finishes will not stick to shellac that has not been dewaxed.

    Shellac is a better water vapor barrier than poly. Maple is a close grained wood that will allow most any film finish to build quickly.

  6. #6
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    Poly is not nearly as hard as shellac. Poly is tough, not hard, there are other varnishes that are harder and better than polyurethane varnish. Waterlox and Behlen's Rock Hard come to mind as does Pratt & Lambert #38. The first 2 are a bit harder than the P&L #38 the P&L #38 is much lighter in color and will not darken much with age.

    My pick would be the Waterlox original in gloss for this application.
    Scott

    Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.

  7. #7
    Great, I have a can of the medium sheen of Waterlox Original. Would prefer the gloss but I'll use this one since I have it.

    The directions say wait 24 hours after cleaning however it doesn't say how long to wait in between coats?

    Phil

    Quote Originally Posted by Scott Holmes View Post
    Poly is not nearly as hard as shellac. Poly is tough, not hard, there are other varnishes that are harder and better than polyurethane varnish. Waterlox and Behlen's Rock Hard come to mind as does Pratt & Lambert #38. The first 2 are a bit harder than the P&L #38 the P&L #38 is much lighter in color and will not darken much with age.

    My pick would be the Waterlox original in gloss for this application.

  8. #8
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    I like to wait 2 to 24 hours depending on how it's drying. Waterlox is a slow drying varnish. Once it's dry-to-the-touch you can recoat it.
    Scott

    Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.

  9. #9
    I'm panning on putting on 3 to 4 coats of the Waterlox medium sheen. If I wanted to add gloss can I finish with a oil based gloss poly as the topcoat?

    Thanks

    Quote Originally Posted by Scott Holmes View Post
    I like to wait 2 to 24 hours depending on how it's drying. Waterlox is a slow drying varnish. Once it's dry-to-the-touch you can recoat it.

  10. #10
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    I'd personally be very tempted to just use multiple coats of Seal Coat and forget about a poly or varnish top coat....

    That's just me though.

    The Seal Coat (Zinssser's prepackaged dewaxed shellac) will build ( 5 or 6 coats) to a very high gloss.

    Being refined to remove the trace carbon (oragnics) elements normally found in shellac, the Seal Coat is more tolerant of incidental contact with water.


    There's also an offbeat alternative which I believe the "turners" are using with quite a bit of success.
    I know custom knife makers started using it over a decade ago.

    That alternative is:

    CA glue.

    Reportedly, CA glue gives a deep gloss, tough, long wearing and waterproof finish.
    I've personally never used it myself, but, I have some handles coming up that I plan on making where I'm going to try it.

  11. #11
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    I would say putting poly on top of Waterlox is about the same a screen door on a submarine.

    The Waterlox Original Gloss is harder, more durable, and glossier than any poly. Are you using satin? I don't think they make a semi-gloss.

    After it has cured it can be buffed up to a higher gloss... This is not possible with polyurethane varnish.
    Last edited by Scott Holmes; 12-05-2010 at 10:49 PM.
    Scott

    Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.

  12. #12
    Scott, yes it's the medium sheen.

    How would recommend buffing the last coat?

    Thanks,
    Phil

    Quote Originally Posted by Scott Holmes View Post
    I would say putting poly on top of Waterlox is about the same a screen door on a submarine.

    The Waterlox Original Gloss is harder, more durable, and glossier than any poly. Are you using satin? I don't think they make a semi-gloss.

    After it has cured it can be buffed up to a higher gloss... This is not possible with polyurethane varnish.

  13. #13
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    You will need to use the gloss. Let it cure for a few weeks then buff, car polish may work if there are no large defects or dust bunnies. If there are you'll need to start at 1000 or 1200 grit wet/dry sand paper. USe mineral oil (slower cutting) or mineral spirits to lube the sanding. This is not long heavy sanding just enough to gey a uniform scratch pattern then move to the nxt finer grit.

    MicroMesh is my favorite "sandpaper" for wet sanding. Using it wet will make it last a long time.
    Scott

    Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.

  14. #14
    If you want a shiny hard decorative finish you might try automotive clear coat. Build a bunch of coats, sanding as you go. You can do a glass like surface this way. Long term the Waterlox might be better since you could repair it pretty easy. The CA glue is not a bad idea either.

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