Painting MDF is Maddening(used a new to me product to help)

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  • ClosetSciFiGeek
    Senior Member
    • Oct 2009
    • 247

    Painting MDF is Maddening(used a new to me product to help)

    I have never tried to paint my speakers I have always veneered them. This is really really difficult. After multiple iterations of sand and try a new method(three times) this has worked the best for me. Best of luck this can be a maddening to find the right process. I know there are some older threads covering this, but I thought I would post the method that finally worked for me after using a product new to me(Bulls Eye 1-2-3 Primer Sealer Stain-Killer) that did a great job of covering and sealing the end grain and roundover of my bases and baffles on the ZDT3.5's I am finishing.

    1) Hand Sand any machined edge(like 3/4" roundover or end of butt-joint to 400grit
    2) Skim coat with Auto Body Finishing Compound and allow to dry fully
    3) Sand to get rid of all small pock marks down to 400grit
    4) Wipe down with tack cloth and then acetone until the paper towels aren't pink anymore(usually the finishing compound is pink)
    5) Immediately shoot with Bulls Eye 1-2-3 Primer Sealer Stain-Killer
    6) Allow to dry overnight
    7) Sand to 400 grit(the primer is very thick, but go easy)
    8) Wipe down with tack cloth then acetone until no more debris comes onto the paper towel(I use the blue ones from autozone so I can tell when I am done because the primer is white)
    9) Immediately shoot Appliance Hard Enamel Paint(this stuff is semi-self leveling and harder for us DIY guys to screw up, plus it is really hard and durable when dry)
    "You get what you Inspect, not what you Expect"
    -Hyman G. Rickover
  • dumaresq
    • Mar 2008
    • 96

    How important is "immediately shoot with Bulls Eye 1-2-3 Primer Sealer Stain-Killer" What happens if you don't do it immediately?


    • evilskillit
      Senior Member
      • Oct 2008
      • 468

      I would imagine you want to do it immediately so you don't leave time for more junk in the air to settle on the surface and get stuck in your paint. So if you want a good clean finish then I think that would be quite important.


      • dpg
        Junior Member
        • Dec 2009
        • 27

        What paint did you use? Something like this?

        You don't think it'd be better off using _____ paint and then shooting it with a good clear coat? I've had good luck getting painted MDF looking good, but my finishes haven't been very durable. Kids can sure test a finish!

        I've read about folks skim coating with bondo... is that for durability, to seal the wood, or to get it looking better? I haven't tried it before but it sounds unnecessary. What's the consensus on that?

        Thanks for putting this together!


        • ---k---
          Ultra Senior Member
          • Nov 2005
          • 5202

          And hope that the seems don't reappear in a few months. A lot of people have problems with this. I think the wood continues to move due to temperature and moisture and the paint can't handle the movement. Some theorize that the finishing process dumps a lot of moisture into the MDF, and that as it dries out the wood will shrink causing the seems to reappear. Some have suggested sealing the backside also, so that the moisture can't escape. Seems reasonable. There is a thread going on at PE where a guy is testing different techniques.

          I don't mean to be a downer or to say you're doing it wrong. I really don't know as I typically don't use MDF. I hope this works for you. I think your autobody filler will work well.
          - Ryan

          CJD Ochocinco! ND140/BC25SC06 MTM & TM
          CJD Khanspires - A Dayton RS28/RS150/RS225 WMTMW
          CJD Khancenter - A Dayton RS28/RS150/RS180 WTMW Center


          • ClosetSciFiGeek
            Senior Member
            • Oct 2009
            • 247

            Not Claiming Mine is the Only Way

            The link you provided above is the exact paint that I shot.

            The reason to immediately shoot paint after the acetone is like stated above to ensure a completely clean and degreased surface.

            I made a mistake in my process above, though. Don't acetone the primer only the bondo finisher. You only tack cloth the primer after sanding.

            Based on all my research and trial and error you are going to have some seams show through on edges no matter what you do. Usually not right away if you did a good job initially. I only painted the front baffles and the bases of my ZDT3.5's because I didn't want to deal with the seams. I have veneered the rest of the enclosure.
            "You get what you Inspect, not what you Expect"
            -Hyman G. Rickover


            • technodanvan
              Senior Member
              • Nov 2009
              • 986

              To me....the cost of paying someone to fiberglass and paint my towers was completely worth it. I've spent a massive amount of time and money in the past to try it with fairly awful results and until I have a garage of my own to house proper equipment I just can't see trying again. I really wonder if the cost of materials alone would have approached the cost of paying someone to do it.

              Image not available

              I feel it's not really DIY now though, even though everything else was done by me. I'm....a cheater.
              Last edited by theSven; 05 July 2023, 14:29 Wednesday.
              - Danny


              • ClosetSciFiGeek
                Senior Member
                • Oct 2009
                • 247

                Kinda with you on that I almost threw in the towel

                I considered buying some 3/4" oak for my baffle and bases for my ZDT3.5's and washing them with a black stain to leave the woodrgrain visible and then clearcoating them. With all the processes I tried it probably would have been cheaper to buy actual real wood vice mdf. The up side to the ZDT3.5 design is that I could veneer the entire enclosure and screw up on the baffles and bases multiple times since I am bolting them to the enclosure. Who knows I may go and remove my painted pieces and install just what I described. Know it would be easier to finish.
                "You get what you Inspect, not what you Expect"
                -Hyman G. Rickover


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