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  • Piano Gloss attempt - what went wrong?

    Trying to make piano gloss black speakers.
    5 coats of flat black paint (rattle can), sanded with 400 grit between coats. My last coat of black paint was wet sanded with 600 and 800 grit. Looked very smooth and even.
    8 coats of high gloss water based polyurethane from a spray can. Sanded with 600 grit between coats on the early coats, realized this may be too fine and did 400 grit between the last two coats.
    They "looked" good after that last coat but obviously needed to sand the unevenness of the last coat of poly.
    After that last coat, I wet sanded with 400, 800, 1500, 2000, and 3000.
    My next steps were to be swirl remover and polish but I'm not sure what I want to do.

    The surface is literally as smooth as glass. The flawed finish is below the last coats of gloss. I'm not sure if it is unevenness in the last coat of paint before the poly or the first few coats of poly.

    What went wrong?


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  • #2
    If going for gloss piono black, I recommend using gloss paint, not flat, preferably krylon. Then clear coat instead of poly. I don't know if this will solve your problem but it is what works for me.
    Carbon13

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    • #3
      How do you sand the last coat of gloss paint before the clear coat?
      What do you use for "clear coat"? I thought that was a general term and poly would fall into that category since it is clear and a coat?

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      • #4
        The uneven result probably indicates sand through of the clear coat. 400g is too coarse unless used very sparingly. I don't use coarser than 800g. If there's a mistake that fine finishing newbies make it's usually sanding too much. You also need to use the right technique. Apply the water with a spray bottle, and put a few drops of detergent in the water as a lubricant, otherwise particles that are sanded off can scratch the finish. Never spray the surface to be sanded, spray the paper, which flushes away sanding residue.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          It all depends on what type of paint you used. If you used an enamel based paint use an enamel clear coat. If using lacquer paint, use a lacquer clear over it. Poly is not compatible with lacquer, it can be used over enamel with a caveat - it has to be completely dry. Even though it feels dry to the touch it is still gassing out, if you seal it too soon with something like poly that gas has nowhere to go and you will have problems. Not sure how long you let it dry but I would give it at least 2 weeks. Or better yet, use an enamel clear instead. I know that does’nt help fix the problem. The only real fix at this point is sanding it all off and starting over, probably not what you want to hear😟. I had to learn this the hard way as well. Sent from my iPhone using Tapatalk

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          • #6
            Originally posted by billfitzmaurice View Post
            The uneven result probably indicates sand through of the clear coat. 400g is too coarse unless used very sparingly. I don't use coarser than 800g. If there's a mistake that fine finishing newbies make it's usually sanding too much. You also need to use the right technique. Apply the water with a spray bottle, and put a few drops of detergent in the water as a lubricant, otherwise particles that are sanded off can scratch the finish. Never spray the surface to be sanded, spray the paper, which flushes away sanding residue.
            +1, forgot to mention that. Over sanding will get you every time. Sent from my iPhone using Tapatalk

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            • #7
              I have always wanted to challenge the piano paint, but it is too difficult.
              I saw a very complete video of making speaker piano paint, I hope to help you!

              https://www.youtube.com/watch?v=vgXw8yl8sJs

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              • #8
                Originally posted by billfitzmaurice View Post
                The uneven result probably indicates sand through of the clear coat. 400g is too coarse unless used very sparingly. I don't use coarser than 800g. If there's a mistake that fine finishing newbies make it's usually sanding too much. You also need to use the right technique. Apply the water with a spray bottle, and put a few drops of detergent in the water as a lubricant, otherwise particles that are sanded off can scratch the finish. Never spray the surface to be sanded, spray the paper, which flushes away sanding residue.
                I did do some research and got the wet sanding technique that you described correct. But that may be the only thing I got correct. I think I over sanded as you said and used sub optimal materials.

                Originally posted by jtheisen521 View Post
                The only real fix at this point is sanding it all off and starting over, probably not what you want to hear😟.
                I pretty much expected that. My goal now is to get the advice I need and get it right this next time. I think I'll burn the cabinets in the fire pit before I'd try a third time though.

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                • #9
                  Been there, I’ve struggled with this a couple of times, got pretty decent results last time around using the following; - use a good high build primer, at least 2 coats, wet sand as Bill described, I used 800 - I usually apply 2 light coats of enamel between standings for a total of 8. You can apply them same day but a few hours apart. Let each 2 coat application cure for a couple days before sanding, then wet sand with 800/1000. Be sure to thoroughly clean off all residue with a damp rag after each sanding. - let the final 2 coats cure for at least a week before sanding, then repeat the 800/1000 routine. - before applying the clear, go over every inch and correct any imperfections. Once your spray the clear they will be locked in and magnified. - spray the clear us is the same 2 light coats/sand procedure. For 4 coats total. - wet sand lightly with 800/1000, follow up with fine rubbing compound then a polishing compound. You can take it a step further and wax if you’d like. A couple extra tips; - always use a sanding block to apply even pressure. - never sand in the same place that you spray, sanding dust gets everywhere and will come back to haunt you. I use a little cart on wheels and roll them outside to sand. Wipe down everything, including the cart before bringing them back in. YMMV, but this has worked well for me, good luck! Sent from my iPhone using Tapatalk

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                  • #10
                    Since you have your prep done, and they are smooth as you want, allow them to dry. You can always lay on more paint without removing the entire process. The prep is done, and it's good.

                    If the streaks are your only concern, I would get some VHT lens-tint spray. This is a black impregnated clear. 2 coats, and you won't see the streaks any more. You can sand and hit a 3rd, but i've never needed to.

                    Later,
                    Wolf
                    "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                    "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                    "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                    "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                    *InDIYana event website*

                    Photobucket pages:
                    http://photobucket.com/Wolf-Speakers_and_more

                    My blog/writeups/thoughts here at PE:
                    http://techtalk.parts-express.com/blog.php?u=4102

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                    • #11
                      Some of these may be duplicate suggestions from the previous posts

                      1. Black should be gloss
                      2. Way too much material
                      3. Incompatible products - pick a paint formula and stick with it
                      4. Don't cut through the final black coat before the clear coat
                      5. Consider skipping the clear coat
                      6. 600-800 between coats
                      7. Block, block, block - Large flat surface I'd probably use a 17" hard
                      8. Never sand where where you paint - blow it off, wipe it down with a rag dampened with a compatible cleaner, repeat and then tack rag
                      9. Wait or bake before the final cut and buff - rattle can finishes are SOFT
                      10.Practice, practice, practice

                      I would suggest painting out a practice piece before you do your cut and buff. Always go over the edge not into the edge so you don't grab and cut you final finish coat.

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                      • #12
                        Originally posted by Wolf View Post
                        Since you have your prep done, and they are smooth as you want, allow them to dry. You can always lay on more paint without removing the entire process. The prep is done, and it's good.

                        If the streaks are your only concern, I would get some VHT lens-tint spray. This is a black impregnated clear. 2 coats, and you won't see the streaks any more. You can sand and hit a 3rd, but i've never needed to.

                        Later,
                        Wolf
                        Pretty cool tip Wolf. I'm trying it and will post how it turns out.

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                        • #13
                          I would strip it. Typically you don’t want to mix water based clear over a solvent based base. Even if you get something over the top now that looks good the paint job will likely show issues in the future.

                          I have spent the last year trying to get this process down. Here is my process:

                          1) sand wood with 80 grit
                          2) body filler and block sand with guide coats. The filler can be spread with a plastic spreader or you can spray polyester high build primer (evercoat slicksand or featherfill g2).
                          3) block sand with 220 with guide coat, repeat if necessary until you get it flat.
                          4) block sand to 360 with guide coat
                          5) spray a sealer at least 2mil thick so you don’t get filler bleed through.
                          6) spray base coat (black)
                          7) spray clear
                          8) wet sand 800 grit. If there is even a hint at you sanding through the clear respray a couple coats of clear, typically overthinned a bit to improve flow out
                          9) work your grits up to 5000. I sand up to 1500 with a block and then switch to the DA for 3000 and 5000
                          10) buff with three stage system, done.

                          It’s tough to do with a rattle can, it’s hard to get even spray. It’s also expensive. Consider getting a cheap hvlp gun. If you do stick with the rattle can consider the 2k clear with the plunger you break in the bottom. Catalyze clear can be built more and cures much harder so it is easier to color sand. Getting away from the rattle cans saves a ton of money and time though. Even cheap automotive paint applied by a novice will get better results than brushing or spraying with a rattle can in most cases.

                          Edit: this is stuff: https://www.amazon.com/U-S-Chemical-.../dp/B0043B7UQY

                          I think a true piano black is to do about 50 coats of hand rubbed shellac so we will call this a “modern” piano black.

                          These are the current speakers I am working on where I completed this process. I am using a black pearl rather than a straight black though. I have finished the bottoms to make sure my process works and will be spraying the rest soon. -Trevor

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