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Thread: Crazy sealcoat

  1. #1
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    Default Crazy sealcoat

    I am redoing an 1890's victorian and have just finished painting the living room. To protect the mantle I removed it and then plastered and painted. I also redid the woodwork with sealcoat and it worked great. I then tried it on the mantle, and it worked great everywhere except on the top surface. There were many areas of crazing. I attacked them with fine sandpaper and steel wool and got a nice clean surface and stained the light spots where I got a bit too enthusiastic in my sanding. I wiped it all down and left it for a day and tried another coast of sealcoat and got the same problem:

    Here is another view:



    And another:



    I am trying to get the living room done this weekend. What am I doing wrong? Or what can I do to fix this crazy crazing problem??

  2. #2
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    Exclamation Re: Crazy sealcoat

    Just a few more bits of info: The only surface prep I did before the first Sealcoat was using steel wool and mineral spirits to clean up the surface. I then applied a single coat of Sealcoat. After the crazing, I got out the palm sander and using 120 -150 grit paper took down the surface until the crazing was almost gone ( I didn't want to hit the wood surface or affect the patina (though that did happen in two small spots)), and then buffed it out after staining with steel wool and spirits. Then I did a single sealcoat after that with results seen above. Any help appreciated!

  3. #3
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    Default Re: Crazy sealcoat

    I'm gonna guess that the mantel was originally a shellac finish, and your "sealcoat" stuff is lacquer-based. That's what happens when lacquer goes on top of shellac. You can wet-sand it out (1500 grit), or start over with some liquid stripper to get to bare wood, at which time you can apply anything you wish.
    S_M
    Remove not the ancient landmark, which your fathers have set.

  4. #4
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    Default Re: Crazy sealcoat

    Quote Originally Posted by Sombreuil_mongrel View Post
    I'm gonna guess that the mantel was originally a shellac finish, and your "sealcoat" stuff is lacquer-based. That's what happens when lacquer goes on top of shellac. You can wet-sand it out (1500 grit), or start over with some liquid stripper to get to bare wood, at which time you can apply anything you wish.
    S_M
    I think it is an original shellac finish (though it may have been varnished over at some point in the past 120 years - probably when the upper mantle was removed (the ghost image ofwhich is still visible on the mantle)) and the Sealcoat is Zinnser's no wax shellac:

    http://www.rustoleum.com/CBGProduct....=246&sid=00850

    Since I was under pressure to finish I simply got out the Johnson's paste wax and attacked the mantle's surface with medium and then fine and then super fine steel wool and wax. Buffing it out gave me a perfectly acceptable finish on the mantle. I'll post pix when I can.

  5. #5
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    Default Re: Crazy sealcoat

    Quote Originally Posted by nylicens View Post
    I'll post pix when I can.
    Here is the finished product:

    Happily the Johnson's paste wax and the steel wool and some effort did the trick.

  6. #6
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    Default Re: Crazy sealcoat

    Nylicens,

    Did you use "Sealcoat" brand sealer by Zinsser? Sealcoat is de-waxed shellac and is generally a great sealer and bondcoat. It is often used by floor people to guarantee adhesion to questionable varnishes with which poly-urethane would not be compatible. Sealcoat will stick to almost anything and poly-urethane will stick to it.

    Do you know what kind of finish the old coat was? Years ago a common floor treatment was to stain, shellac and wax. It is also possible the floor has been treated with other non-compatible finishes over the years, also the top of the fireplace mantle.

    Sealcoat would not be compatible with any residual wax. Also, the mineral spirits used to clean the floor could be leaving an oily residue, as could any residual stain which is lying on the surface, having not pentrated the wood. Again, Sealcoat would not be compatible with such residue.

    If, indeed, your "sealcoat" is lacquer based, Sombreuil could be correct in his advice. You might want to get a floor company in to give you advice as how to proceed. Lacquer would not normally be used on existing varnish, as its solvents are far too agressive and can eat into older varnished surfaces.

    To me, it is significant that you had no problem with the woodwork. People would not normally have put on a "protective" finish of wax on woodwork, however, they may very well have used wax or vinyl type finishes on the floor or mantle.

  7. #7
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    Default Re: Crazy sealcoat

    Nylicens,

    Sorry, I must have just missed your last post where you confirm it was "Sealcoat". I always hated working on unknown varnished surfaces where the history of what was used on it is not known. Usually a squirt of water will give you a hint as to weather wax is present. Water will bead up on wax and eventually turn it white. If water beads up on a surface, varnish or poly-urethane will also have a problem adhering to the surface.

  8. #8
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    Default Re: Crazy sealcoat

    Quote Originally Posted by ordjen View Post
    Usually a squirt of water will give you a hint as to weather wax is present. Water will bead up on wax and eventually turn it white. If water beads up on a surface, varnish or poly-urethane will also have a problem adhering to the surface.
    Thanks for this tip. I still have a lot of woodwork to go...

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