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  1. #1
    Join Date
    Dec 2008
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    Question How to get a piano black finish?

    Fellas I need help. I want to get a black piano finish on my unfinished 3/4" mdf enclosures. Info. on materials and neccessary steps to get a great finish will be sweet. Attached is a pic of the spkrs. as they set now. You can view more about the speakers on http://pwkdesigns.com/blog/index.php...y081215-100000 2-Way 5.1 Surround Upgrade "Sculpture 102.1"
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  2. #2
    Join Date
    Oct 2005
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    Ballwin, MO 38.597554, -90.547423
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    Default Re: How to get a piano black finish?

    Quote Originally Posted by dgibb79 View Post
    Fellas I need help. I want to get a black piano finish on my unfinished 3/4" mdf enclosures. Info. on materials and neccessary steps to get a great finish will be sweet. Attached is a pic of the spkrs. as they set now. You can view more about the speakers on http://pwkdesigns.com/blog/index.php...y081215-100000 2-Way 5.1 Surround Upgrade "Sculpture 102.1"
    Sanding, sanding, and more sanding.

    Seal the MDF with Elmers "painted" all over the surface. Once dry, sand, sand, sand, with ever finer grit. Once you've reached 400 or so, you're ready to try some paint.

    Love "The Boondocks."

  3. #3
    Join Date
    Dec 2008
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    Alabama
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    Default Re: How to get a piano black finish?

    Would stain be fine? I was thinking about using some ebony black oil-based stain by mini-wax and mini-wax polyurethane for finishing. So if the elmer's seal keep the mdf from soaking up the stain how many coats?

  4. #4
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    Default Re: How to get a piano black finish?

    Quote Originally Posted by dgibb79 View Post
    Would stain be fine? I was thinking about using some ebony black oil-based stain by mini-wax and mini-wax polyurethane for finishing. So if the elmer's seal keep the mdf from soaking up the stain how many coats?
    One coat of Elmers should do it. The main thing is prepping the surface to get it smooth as glass and without undue undulations so you get that piano finish.

    And I'd use just your standard black spray paint, with a sanding session between coats. After a few coats of paint when you're happy with the look, then the urethane, sanding between coats, until you have the liquid look you are looking for.

  5. #5
    Join Date
    Dec 2008
    Location
    Alabama
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    30

    Default Re: How to get a piano black finish?

    Sounds simple enough. Is it possible to get a smooth look using a good natural bristle brush? I'm thinking about purchasing a 5hp compressor and a good hvlp gun. When applying the poly finish, do I suppose use a rubbing compound to bring out the desired shine between coats?

  6. #6
    Join Date
    Jun 2007
    Location
    South Dakota
    Posts
    910

    Default Re: How to get a piano black finish?

    I've used several coats of diluted Titebond II as a base coat, let dry for a day or two, lightly sanded smooth then finished up with a coat of clear poly! I ususally let set for another day or two then proceed from there!

  7. #7

    Default Re: How to get a piano black finish?

    I would read over the this thread over at diyaudio towards the end take note of MJL21193's posts.

    If i were you i would stay away from anything water based as a primer/sealer(elmers). Im going to follow MJ's technique of using polyurethane as a primer/sealer, sand, "rustoleum stops rust" black-gloss enamel (MJ uses tremclad) then clear with more poly. Cut the rustoleum by about 30-40% with mineral spirits (it will dry very fast this way. Im still not sure on which clear top im going to use.

    Wait a few days between steps. IMPORTANT!

    I would also recommend a flush trim bit instead of sanding with a heavy grit sand paper on panel end grain. Im starting to think that joint lines are more the result of the grain being disturbed and unfurling other than moisture being the sole reason for expansion lines.

    take your time and do some tests on scrap mdf.

  8. #8
    Join Date
    Oct 2005
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    Ballwin, MO 38.597554, -90.547423
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    Default Re: How to get a piano black finish?

    Quote Originally Posted by tech9_79 View Post
    I would read over the this thread over at diyaudio towards the end take note of MJL21193's posts.

    If i were you i would stay away from anything water based as a primer/sealer(elmers). Im going to follow MJ's technique of using polyurethane as a primer/sealer, sand, "rustoleum stops rust" black-gloss enamel (MJ uses tremclad) then clear with more poly. Cut the rustoleum by about 30-40% with mineral spirits (it will dry very fast this way. Im still not sure on which clear top im going to use.

    Wait a few days between steps. IMPORTANT!

    I would also recommend a flush trim bit instead of sanding with a heavy grit sand paper on panel end grain. Im starting to think that joint lines are more the result of the grain being disturbed and unfurling other than moisture being the sole reason for expansion lines.

    take your time and do some tests on scrap mdf.
    Why stay away from Elmers or Titebond? The enclosure is likely bonded together with those adhesives already. Not only that, but the subsequent coats of paint and laquer/urethane will remove any possibility of exposure of the underlying Elmer's. Not only that, MDF is already quite susceptible to moisture. Keep in mind, that these are indoor speakers and not likely to see huge swings in humidity. And if they do see high humidity, a coat of urethane where the Elmer's was, followed by coats of paint and clear, won't do any more to seal the MDF than the Elmer's did, unless you coat both inside and outside the enclosure, even the driver cutouts.

  9. #9

    Default Re: How to get a piano black finish?

    I found the piano gloss to be relatively easy! Yes , much sanding for a smooth start. Then black spray paint , several coats , then many coats of clear coat , followed by allot of sanding! The last step involves rubbing compound and a soft cloth to bring the surface to a glassy , reflective finnish!
    It is allot of work but it is so worth it!
    Ryan.
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  10. #10

    Default Re: How to get a piano black finish?

    Any of the hard enamel metal paints are the way to go (HVLP)! Do all the finishing tips mentioned above. Then to top it all off buff by hand with Mothers or other high quality auto wax! Seriously do the wax thats what makes them pop!!

  11. #11
    Join Date
    Aug 2006
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    N. Illinois
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    Default Re: How to get a piano black finish?

    Hogwash.


    Quote Originally Posted by tech9_79 View Post

    I would also recommend a flush trim bit instead of sanding with a heavy grit sand paper on panel end grain. Im starting to think that joint lines are more the result of the grain being disturbed and unfurling other than moisture being the sole reason for expansion lines.
    ~99%
    Make me an angel that flies from Montgomery
    Make me a poster of an old rodeo
    Just give me one thing that I can hold on to
    To believe in this livin' is just a hard way to go


  12. #12
    Join Date
    Feb 2009
    Location
    Courtice, Ont.
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    968

    Default Re: How to get a piano black finish?

    Quote Originally Posted by Ryan View Post
    I found the piano gloss to be relatively easy! Yes , much sanding for a smooth start. Then black spray paint , several coats , then many coats of clear coat , followed by allot of sanding! The last step involves rubbing compound and a soft cloth to bring the surface to a glassy , reflective finnish!
    It is allot of work but it is so worth it!
    Ryan.
    Ryan, What paint ant clear coat did you use? Also how durable is the finish?

  13. #13

    Default Re: How to get a piano black finish?

    Quote Originally Posted by bobbarkto View Post
    Hogwash.
    Think about it, mdf is wood fiber compressed and bound by resin. The weakest points are at the panel ends, If something like your saw blade ect is not entirely sharp the resin in the end grains is broken apart. Feel the ends of your panel after cutting with a sharp blade, hard & rigid. with a dull blade or lots course sanding the ends are kind of spongy. I think the ends then kind of mushroom out, showing lines. A sanding sealer or hard primer helps stop this, holds things in place and can be finished sanded.

    Expansion lines have been talked alot about in other forums and it seems that moisture was not the only problem. Even the pro's were scratching their heads.

    Its just my theory. But if my hog is washed, it shows no lines..
    Last edited by tech9_79; 07-30-2009 at 12:48 PM.

  14. #14

    Default Re: How to get a piano black finish?

    I added some relevant points in this thread:

    http://www.audiocircle.com/index.php?topic=69840.0

  15. #15
    Join Date
    May 2008
    Location
    manassas, va
    Posts
    1,360

    Default Re: How to get a piano black finish?

    This may be of help - from the PE showcase. Read towards the bottom.

    http://www.parts-express.com/project...fm?project=SO1
    If dynamite was dangerous, do you think they'd sell it to an idiot like me?

  16. #16

    Default Re: How to get a piano black finish?

    Next, it's onto the internal electronics. Since the original (Sculpture 101) build, I've gotten a lot of inquiry about my crossover networks. For the tweeters, I'm using a 2nd order Butterworth high-pass filter (C=4.7uF, L=0.6mH,) resulting in a 12dB per octave cut-off at 3000Hz, while the midbass drivers are left to accept the full bandwidth.
    Interesting "crossover"..

    and it would seem this plus a little more bondo+sanding might do the trick, with a little less work.

  17. #17
    Join Date
    Jul 2009
    Location
    Detroit area
    Posts
    40

    Default Re: How to get a piano black finish?

    Is there any reason to use spray paint over just rolling on the black? I use one of those mini "sponge" type rollers and seem to get a good smooth finish. Haven't used it to try a piano finish though.

  18. #18

    Default Re: How to get a piano black finish?

    I used Varathane "colors in plastic" plastic enamel , it is an interior / exterior paint , the clear coat is Varathane "professional clear finish".
    And as someone else pointed out , waxing the final product does help make them look awesome!
    As far as durability , I haven't really tested them!
    Ryan.

  19. #19
    Join Date
    Aug 2008
    Location
    council bluffs iowa
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    7,369

    Default Re: How to get a piano black finish?

    paint is more difficult to sand save it until your surface id perrrrrfect. use regular primer and sand, sand, sand. wipe off with a damp cloth to spot the imperfections.

  20. #20
    Join Date
    Aug 2006
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    N. Illinois
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    Default Re: How to get a piano black finish?

    That says it all. Wood will always shrink and swell with changes in moisture content.
    It doesn't matter if the moisture is induced by glue, a finish or the atmosphere (which is always present and always has an effect).

    In your example of a rough edge you will probably see the loose fibers create a rough texture when atmospheric moisture is absorbed. But you will also be able to measure the panels and see that they have also expanded.
    MDF, particle board and wafer board will move almost equally in every dimension.
    Solid wood always expands more in width, across the grain. But will expand a comparitevly small amount in length, along the grain.
    Plywood is similar to mdf except there is more expansion in thickness and nearly equal expansion in length and width.

    No primer or finish will stop any wood or product made from wood fibers from expanding and contracting with those changes in atmospheric moisture (humidity). That's unequivocal.

    The very best products will limit the amount and rate of moisture exchange but will not stop it completely. The very best products and procedures can practically eliminate the problems associated with moisture induced movement in some cases.

    Schtoo and Shin are in the UK. They see a lot of humidity and a lot of movement in their wood products. Some folks in drier climates and where humidity is well controlled indoors never experience a problem, provided they have used sound fabrication and finishing methods.

    Those "pros" who are still scratching their heads haven't done their homework or just plain refuse to believe that something so simple and well known can be the cause of their problems. And those that deny the problem exists aren't experienceing the problem or don't notice it because their level of finishing is not up to revealing subtle aberrations in the surfaces they create.

    Quote Originally Posted by tech9_79 View Post
    Think about it, mdf is wood fiber
    ~99%
    Make me an angel that flies from Montgomery
    Make me a poster of an old rodeo
    Just give me one thing that I can hold on to
    To believe in this livin' is just a hard way to go


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