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Thread: Should I apply wax over polyurethane?

  1. #1
    Join Date
    May 2010
    Location
    Park Hills, KY - Cincinnati, OH
    Posts
    99

    Should I apply wax over polyurethane?

    Hi,

    I just stripped an old china cabinet, used a water based stain, and finished with an oil based polyurethane. This will piece will hold stacks of plates, wine glasses, etc. I am concerned that the pressure from the stack of plates will cause the bottom plate to stick, such that I will need to pry it off, and the plate will take some of the poly/dye with it. I have had this happen on another piece before, with poly over paint. Should I apply a liberal coat of wax to the shelves? Is there something else I can do to prevent this? This is our good wedding china I am talking about. If I mess this up, I am a dead man.

    Thanks!
    Chris

  2. #2
    Join Date
    Jul 2008
    Location
    Tomball, TX (30 miles NNW Houston)
    Posts
    2,491
    Poly is one of the softer varnishes, it's tough not hard. Next time pick a hard varnish, e.g. alkyd resin or phenolic resin varnishes are both harder than the standard big box store oil based poly varnishes.


    The wax may help it may not. Has the poly had a month to cure? That would be the most helpful to prevent the blocking. The paint may be the biggest culprit to your past failure.
    Last edited by Scott Holmes; 02-27-2013 at 1:27 PM. Reason: typo
    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.

  3. #3
    In my (limited) experience, wax does nothing but make it look and feel nice for a short while after application. It has no effect on the long term other than it creates a residue that gives you stress if you ever decide to put an additional coat on it. (I love wax for things that are purely display, tho).

    If you are really concerned, you can topcoat the poly with the varnishes that Scott recommends. To insure compatibility, you can spray a barrier coat of shellac first.

    However, I will say that even with a phenolic varnish (I've used Waterlox), you WILL get blocking from something as light as a computer laptop or planter if you do not let the finish cure. You really have to let it sit for a few weeks unloaded in good temps b4 putting anything on it; and don't think that putting a textured towel between the surface and the item counts; that too will leave marks - just prettier ones.

    If it were me, (time allowing) I'd be inclined to let the poly cure and load it up in a discreet place as a test. I have a bench of poly that WAS cured properly and it's really difficult to damage the finish; I believe you will be fine.

    I had similar blocking issues when I polycrylic topcoated a latex painted surface. At the same time I polycyl'd an unpainted workbench. The bench does not block; the art table does. I concluded that it has to do with the paint. But YMMV.

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