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  • Painting MDF

    Im almost finished with my speaker cabinets and I will be getting ready to paint them soon. I'm reading that it is difficult to paint MDF especially the edges. Can someone help me with some known products and procedures for filling, sealing, and painting MDF cabinets please? I would love for them to be gloss white. Thanks Mike D.

  • #2
    Re: Painting MDF

    Originally posted by Mike47 View Post
    Im almost finished with my speaker cabinets and I will be getting ready to paint them soon. I'm reading that it is difficult to paint MDF especially the edges. Can someone help me with some known products and procedures for filling, sealing, and painting MDF cabinets please? I would love for them to be gloss white. Thanks Mike D.
    On the edges of MDF I use titebond 3 uncut or right out of the bottle. I put on a pair of nitrile gloves and push it into the edges but dont let it build up, wipe off with an old
    t-shirt and repeat when dry. Usaully 2 coats are enough, then lightly sand before proceeding.
    Next I coat the whole box with a inexpensive waterbase poly (Minwax Polycrylic). Let it dry
    thoroughly 48hrs,sand lightly and finish with paint of your choice.

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    • #3
      Re: Painting MDF

      As I've already replied to Mike privately I use a shellac- or oil-based primer on MDF before painting. Two coats with sanding in between on the edges perfectly seal them.
      Paul

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      • #4
        Re: Painting MDF

        +1 on the shellac. always have had really good luck using it.
        craigk

        " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

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        • #5
          Re: Painting MDF

          Best stuff I've tried yet is Zinsser BIN. Shellac based primer. Seal and prime in one step. Use some bondo or wood filler on your seams, make sure they are smooth or the seams will show through the paint.
          "I just use off the shelf textbook filters designed for a resistor of 8 ohms with
          exactly a Fc 3K for both drivers, anybody can do it." -Xmax

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          • #6
            Re: Painting MDF

            pretty much any kind of heavy solids primer with sanding in between will smooth out the mdf edges. i use methods similar to what paul k and dcibel mentioned regularly.

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            • #7
              Re: Painting MDF

              I tried some spray BIN and some "automotive fast-build primer" and liked the car primer better. Seemed to be easier to sand between coats and dried quicker.

              There's several things that work -- just make sure you give whatever approach you use time to dry completely before you try finishing the whole thing.

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              • #8
                Re: Painting MDF

                I use Minwax Wood Hardener on the board ends and seams. Then the auto high build primer mentioned above. I also use the hardener on the driver cutouts so the wood doesn't swell when I prime/paint it, which causes the driver flange to sometimes not be flush with the surface the way you intended.
                ~Brandon

                Soma Sonus
                DriverVault

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                • #9
                  Re: Painting MDF

                  Hello,

                  trying to keep the number of different products in my workshop down, I tried using ordinary wood-glue and found that this (one layer 50/50 water, two layers glue) worked just fine!

                  Regards//lasse
                  Perry Mason talking to his dentist:

                  "Do you swear to take the tooth, the whole tooth and nothing but the tooth, so help you God?"

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                  • #10
                    Re: Painting MDF

                    I've had good luck using Polycrylic as a sealer coat, however the current build I'm working on, I'm testing a new method. I skinned the cab with 1/8" MDF so the exposed raw edges are only 1/8" wide. My thought is that it should be easier to hide them since they are much narrower, they will also soak up less poly since there's less surface area to deal with. And of course it also brings the wall thickness up to 7/8" which helps to deaden the cab. I'll post a thread with my results as soon as I get started with the finishing, I figure even if they do end up showing they're close enough to the corner that it won't be very noticeable.
                    Click image for larger version

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                    My modest builds:
                    Armadillo TM, A.K.A. Lil' Dillo
                    Tarkus/Armadillo build #2
                    Armadillo Center Channel
                    Au-Rock-O Sub
                    Tarkus
                    Staining MDF tutorial

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                    • #11
                      Re: Painting MDF

                      For the least expensive primer, Shellac based Bin primer works really well.
                      http://www.amazon.com/Shellac-Primer.../dp/B00113UKQY
                      Let it dry 24 hours before sanding or it will build up in your sand paper. It will take several coat to seal up the edges. Don't use the spray kind it is extremely thin.
                      Another thing that works even better is coating the edges with body putty. Just a real thin layer will seal edges right up. It helps to have some body work experience. You have to move fast and mix small amounts.


                      The main thing to remember MDF does not like moisture so the least amount you add in your finish process the better off you will be. That's why I recommend the shellac base primer. It dries quick. Any product that soaks in is not good. It will cause expansion which will cause a better chance of ghosting on the seams when all that moisture disapates.


                      If you really want to hide the seams I have a method in my signature that works. It does take quite a bit of work and some experience. Otherwise enhance the seams because they will more then likely show up over time. Depending on the finish you apply you may not be all that concerned.

                      If you like to read here is a thread that that explains a lot.
                      http://techtalk.parts-express.com/sh...-finishing-MDF

                      Dave
                      http://www.pellegreneacoustics.com/

                      Trench Seam Method for MDF
                      https://picasaweb.google.com/101632266659473725850

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                      • #12
                        Re: Painting MDF

                        Can I sand and repaint acrylic latex enamel if I mess it up the first time? I had to repaint a kitchen cabinet door one time and I had to completely strip the paint because it kept leaving bleed through places. I Don't remember what kind of paint that was.

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                        • #13
                          Re: Painting MDF

                          Is it ok for a little bit of wood to show through the primer after sanding? Ive put on three separate coats of Zinnsers BIN primer sanding between each coat. Even after three coats I still get the wood showing through in some places after sanding. Not real bad, if fact I can still see the primer in the wood, but it is thin. Do I need to keep priming and sanding until no wood shows at all? Thanks Mike D.

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                          • #14
                            Re: Painting MDF

                            What grit paper are you using when sanding between coats?

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                            • #15
                              Re: Painting MDF

                              Originally posted by Leroy R View Post
                              What grit paper are you using when sanding between coats?
                              320 on the flats, 400 on the 45 degree edges.

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