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  • A question for rattle can gurus....

    Hi everyone,

    I'm new here, although I've lurked for a while for past projects. I have a 2 part question here for all the rattle can gurus. I'm actually refinishing some speaker tops/bottoms that will be piano black. I'm going the gloss black/clear over top/polishing compound route, finished with a rotary polisher. Here's my question:

    For the gloss base coat, should I wet sand the last coat before clear?

    If yes should it also be polished with compound and a rotary polisher before moving on to clear?

    Remember, I'm using rattle cans here, not automotive paints. It appears that among automotive painters the consensus is not to wet sand the last base coat before the clear (as long as orange peel has been comepletely removed), although many have done it with great success.

    Before reading more about it my original plan was 4-5 coats of a gloss black base coat, wet sand the base coat, compound with the rotary, then 3-4 coats of clear, wet sanded, then final polish with the rotary. Can anyone share their experiences with this method along with the products you used and specifics of your methods? Thanks ahead of time. Glad to be here.

  • #2
    Re: A question for rattle can gurus....

    I always sand before clear with 2000 grit and I always get a smooth mirror finish, but that is only after curing for at least a week. If you spray a clear coat before the base is fully cured and hardened it will ruin it. That is on computer cases, though I can't see enclosures being any different. I also use polishing/rubbing compound on the clear coat after it has fully cured.

    It sucks, but good results with spray cans require lots of waiting. If you don't let it cure it just won't look as good. Despite what some say, lacquer should treated like enamel when it comes to curing.

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    • #3
      Re: A question for rattle can gurus....

      And the paint you use really matters too.

      Duplicolor spray cans have a great nozzle that delivers a very even spray. I was able to get a really smooth glossy finish on a set of waveguide baffles by starting with a nice coat of Deft Sanding sealer, sanded to 320, followed by a Duplicolor sandable primer. That dried for a couple hours in the summer sun and then I went at it with a dry sand with 400grit followed up with some scotch brite pads to a semi glossy finish. Then the paint went on, again, cured for a couple hours in the sun, followed by a wet sand to 2000, final coat of paint, and then a clear coat over that. The sun is a real asset in getting the pain to dry quickly, as long as it's not put on too thick. The result was a super smooth and even satin finish. I'm sure a gloss coat on top of that would have been possible.

      Love those duplicolor nozzles.
      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

      95% of Climate Models Agree: The Observations Must be Wrong
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      • #4
        Re: A question for rattle can gurus....

        I agree, Duplicolor is about the best for color and clear coats. For primer, if you can find Plastikote it is the absolute best primer there is. It definitely makes a difference.

        Also, a simple rule for paint types if your primer and color are different is you can spray enamel color coats onto lacquer primer, but not lacquer color onto enamel primer. Lacquer is chemically "hotter" than enamel and can react with it during the curing process. Basically you're going to be covering enamel primer before it has fully cured, so it's safer to use a paint with similar characteristics. Since lacquer cures quickly there's usually no problem spraying enamel onto it since the lacquer's chemical reaction has already significantly slowed. That's just what I've read and heard, I'm by no means an expert.

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        • #5
          Re: A question for rattle can gurus....

          There is normally no need to take the base to a very high gloss level. It's usually a waste of time and energy.The clear will handle the gloss. You just want smooth from the gun/can and no gross defects. Get good at laying down a smooth base from the gun/can.

          If the base has gross imperfections then sand them out. For most paint chemistries you want a smooth scratch free surface and that's all.
          If you are using a metallic, flake or other decorative base then don't sand the final coat. You will detract from the effect. If you must sand then apply another base coat before top coating with clear.

          If you are using a lacquer or an acrylic lacquer like Duplicolor there is no need to sand the base more than enough to make it smooth and defect free, usually about 600/800 grit. The initial coat of gloss will partially dissolve into the base removing any slight scratches in the process. You can polish the final gloss coat to your desired sheen.

          If you use an enamel or any urethane, be aware, you can run into problems with this chemistry. The gloss coat needs to be laid down before the base is completely cured or you will have adhesion problems. And it is impossible to sand and polish out an uncured enamel. So lay down a good base. It doesn't have to be perfect or glossy, just smooth. The final clear coats will provide the gloss. If you allow the base to cure enough to sand and polish then you will again have adhesion problems. The top coat won't bond to a polished smooth cured base. You would have to scuff sand the base to give the clear a toothy surface to bond to and then you will see scratches. Again don't sand the final coat of metallics or the like.

          More detailed advise will depend on the specific paint you choose.
          ~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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          • #6
            Re: A question for rattle can gurus....

            With many polyurethanes, your can get a top-coat finish as shiney as a new car if you want. The nicer thing is there are a half-dozen steps down to dead-matte, and using automotive polishing compound(s), you can fine-tune any of them. Lacquers can do the same thing (and now there are many chemistries of lacquers from nitrates to polyurethanes to cyanoacrylates and more), whether their harder or easier to use depends on how you feel about them.
            Personally, I hate rattle cans, due to their pressure loss with use, and their dubious spray nozzles. If I want to use a rattle can paint, I blow the propellant out, then puncture the can and decant the paint and put it in an airbrush, where I can control the pressure, tip, pattern and paint flow. I have a couple of "detail" spray guns which are just "grown-up" airbrushes and hold 6 oz. of color in their cups instead of 3 oz., and will lay it down faster. One's a Paasche, one's a Harbor Freight knock-off (the parts interchange!), and except for me dressing and polishing the HF's needle, for 1/10th the money, unless I was doing mural work, either one is as good as the other.
            I DO prefer Duplicolor paint to never-drying Krylon, or even Rust-O-Leum. The REALLY cheap spray paints don't have the pigment, so they don't have the coverage per coat, but some of that .88 cent per can stuff shot from an airbrush sure dries out looking good.

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            • #7
              Re: A question for rattle can gurus....

              Originally posted by bobbarkto View Post
              There is normally no need to take the base to a very high gloss level. It's usually a waste of time and energy.The clear will handle the gloss. You just want smooth from the gun/can and no gross defects. Get good at laying down a smooth base from the gun/can.

              If the base has gross imperfections then sand them out. For most paint chemistries you want a smooth scratch free surface and that's all.
              If you are using a metallic, flake or other decorative base then don't sand the final coat. You will detract from the effect. If you must sand then apply another base coat before top coating with clear.

              If you are using a lacquer or an acrylic lacquer like Duplicolor there is no need to sand the base more than enough to make it smooth and defect free, usually about 600/800 grit. The initial coat of gloss will partially dissolve into the base removing any slight scratches in the process. You can polish the final gloss coat to your desired sheen.

              If you use an enamel or any urethane, be aware, you can run into problems with this chemistry. The gloss coat needs to be laid down before the base is completely cured or you will have adhesion problems. And it is impossible to sand and polish out an uncured enamel. So lay down a good base. It doesn't have to be perfect or glossy, just smooth. The final clear coats will provide the gloss. If you allow the base to cure enough to sand and polish then you will again have adhesion problems. The top coat won't bond to a polished smooth cured base. You would have to scuff sand the base to give the clear a toothy surface to bond to and then you will see scratches. Again don't sand the final coat of metallics or the like.

              More detailed advise will depend on the specific paint you choose.
              Thanks guys. @bobbarkto, your advice seems to echo what a lot of automotive painters say. I'll probably be using duplicolor enamels for this and part of the reason for wanting to sand the base coat before clear was to remove orange peel. If not sanding the base is the way to go, how do you deal with possibly adding orange peel again when laying another base coat after sanding smooth. Also, does the clear need to be laid down so soon after the base with the duplicolor as with the automotive paints that have such a barrow window for adding the clear?

              So far I'm leaning towards 3 base coats, sand smooth with 1500 grit, one more base coat, then 3 coats of clear and eventually polish with the rotary. Remember I'll be using the Duplicolor enamel black and clear for this.

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              • #8
                Re: A question for rattle can gurus....

                If you wait and sand your color to 1200 you will have adhesion problems with the next coat. So don't do that! ;)

                With enamels there is no practical way to sand your color and remain within the constraints of recoat window and adhesion and scratches showing through to your clear.
                Get a good final color coat from the can is my best advise if using any enamel.

                You should see little to no orange peel from the can if conditions are good. Your biggest challenge is avoiding runs. Canned sprays are very thin.
                In cooler weather a good practice is to warm the can in a container of hot tap water just before use. Helps greatly to promote flowout. Don't warm the can if ambient temp is high, say above 78f or so.

                If you really wreck the color coats then wait a week, sand up to 220 (no finer, you need scratches for adhesion) and then recoat. 2 coats should do hte trick if you have any color left at all.
                Get the clear on within an hour of your last color coat.

                Duplicolor enamel has a 1 hour recoat window. This applies to every coat; color, clear or combination.
                Give yourself an afternoon so you can get all the coats on in time.

                Wait a week or 2 before polishing out.

                You might be seeing some advantage to lacquer at this point. You can achieve just as high a level of gloss and depth without many constraints, but maybe more work (maybe). Trouble is, it's a rather fragile finish compared to most others.

                Hope this is helpful to you.

                Originally posted by dosto233 View Post
                Thanks guys. @bobbarkto, your advice seems to echo what a lot of automotive painters say. I'll probably be using duplicolor enamels for this and part of the reason for wanting to sand the base coat before clear was to remove orange peel. If not sanding the base is the way to go, how do you deal with possibly adding orange peel again when laying another base coat after sanding smooth. Also, does the clear need to be laid down so soon after the base with the duplicolor as with the automotive paints that have such a barrow window for adding the clear?

                So far I'm leaning towards 3 base coats, sand smooth with 1500 grit, one more base coat, then 3 coats of clear and eventually polish with the rotary. Remember I'll be using the Duplicolor enamel black and clear for this.
                ~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

                Comment


                • #9
                  Re: A question for rattle can gurus....

                  This is all great advice. What method should one use to get a smooth but satin finish?

                  Comment


                  • #10
                    Re: A question for rattle can gurus....

                    Thanks everyone. This advice has been exactly what I was looking for. @bobbarkto, you're right about seeing the advantage of lacquers. I know duplicolor offers lacquer versions of some of heir products although I'm not sure I get my hands on them around here, but if I can I just might try them. The warming the can trick has worked well by the way when I have used it. I'm going to go with your exact advice above: black and clear over top immediately after within the 1 hour recoat window, then polish after 1 week + of curing. I'll post some pics when it's all done.

                    Cheers

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                    • #11
                      Re: A question for rattle can gurus....

                      Originally posted by dosto233 View Post
                      Remember, I'm using rattle cans here, not automotive paints. It appears that among automotive painters the consensus is not to wet sand the last base coat before the clear (as long as orange peel has been comepletely removed), although many have done it with great success.
                      It really depends on how nuts you want to go with it, and by that I mean (1) time, and (2) effort. If you are patient and don't mind working on it over the course of a few weeks or months, you can get really great results. I used to airbrush, but I mostly just use spray paint now because the paints are so good these days. I pretty much just use MDF or plywood for my projects - I'm not brave enough to try doing a "real wood" or veneer finish just yet :D Here's my basic process for spray painting MDF, everyone's secret recipe is a bit different, but it should point you in the right direction: (not sure if you're using MDF, but should apply to most any wood)

                      The basic process: (get ready for an information dump after this, haha)

                      1. Smooth coat
                      2. Seal coat
                      3. Prime coat
                      4. Paint coat
                      5. Clear coat
                      6. Wax coat

                      1. Smooth coat:

                      First step is to get the unpainted surface nice & smooth. Basically this involves a lot of sanding and using a fill product - this covers the seams and any holes or nicks you might have in the cabinet (such as screw or nail holes, or chipped MDF corners). I just use Elmer's wood fill in the tub from Home Depot, it's sort of like bondo for wood. Works great - let dry & then sand it. I use a mix of a small orbital sander (like $30 at Home Depot - I'll use Home Depot as the reference, you can use Lowes or whatever you have nearby), a hand block, and just plain sheets wrapped around my fingers. The idea here is to get the surface really nice and smooth, and free of any gouges - the paint is going to show everything you see here, so work on it until it's where you want it to be. The block sander & electrical sander work the best for getting large surfaces done smoothly.

                      As far as sandpaper goes, if you end up using a lot of wood filler, use a low-grit sandpaper like 80 or 120 to cut the shape down. When it's where you want it, use 200/300 to refine it and then finish up with 300 - that will give it some bite for the primer to stick on.

                      2. Seal coat:

                      I like Zissner B-I-N, available at Home Depot. Works great on MDF. MDF is like a sponge and really sucks up paint, so you'll still need a couple coats of this sealer paint, but it gives it a really nice paintable shell when you're finished. Usually takes at least 2 coats of sealer to completely coat the speakers.

                      Sand with 300-grit sandpaper. You want it smooth, but don't sand so much you can see the wood.

                      3. Prime coat:

                      Two coats a day over a 2-day period, 4 coats total. First day: do 1 coat, wait 1 hour, do the second coat. Let dry 24 hours. Second day: sand with 200 then 300 grit, repeat (1 coat, 1 hour dry, another coat).

                      For color, usually either go white, gray, or black. Depending on what final color you want. If you want a black piano finish at the end, obviously go with a darker color like black. If you want white or yellow, go with white. Sometimes people use gray ("silver") for the darker final metallic colors.

                      Make sure that your spray environment is bug & dust free. I use some large cardboard boxes to cover the speakers with after I'm done with each painting pass so that stuff in the air doesn't float onto the finish while it's drying. Use a mask, even a cheap one is better than nothing.

                      There's some pretty simple tricks to priming/painting: first, shake the can for a full minute. Not just a 10-second shake. Second, do the spray in a sweep: hold your arm straight as you pass, and not in a circle/arc pattern, and start pressing the can before you hit the surface, and then let go of the nozzle after you pass the surface. When the paint first starts coming out, it tends to splatter (same at the end), so this way the splatter doesn't end up on your cabinets. Third, overlap half of the previous spray pass with the next one so it will come out uniform. You don't want to move super fast, but you want to move quick enough that it stays wet as you make the passes. And then it will look nice while it's wet and then dry and look like crap, this is normal :D

                      4. Paint coat

                      Now the fun begins! You will begin to loathe sanding at this point ;) So basically the same as priming, but we're going to start using higher-grit sandpaper. So sand down the primer from the day before with 300-grit. Now you do 2 or 3 days of painting, go for 3 if you want a serious finish. Same deal - two coats, let the first coat dry for an hour then let the second coat dry for 24 hours. On the second day, work up from 600 to 800 to 1000 grit then paint. On the third day use 1000. On the fourth day, use 1000. If things get messy, you can use a tack cloth and alcohol to wipe things up. So at this point the paint should be nice and smooth. Oh, and the paint technique is the same - keep it wet, overlap passes, start/stop the nozzle off the workpiece, shake for a full 60 seconds.

                      5. Clear coat

                      This is where things get a bit tricky. Clearcoat is not a magic glossy wet-look cover for your paint. You basically have to bring the shine out with a lot of elbow grease. Make sure to get a clearcoat to match what you are painting (ex. enamel, acrylic, etc.). You don't necessarily need to wet sand to get good results. You can do a few days of clearcoating just like painting - just use 1000-grit the whole time. And you can go totally nuts with this. Back in my airbrushing days, I saw a motorcycle tank that had 17 coats of clearcoat on it. It probably took two or three weeks to do, but the finish was like 10 years old and STILL looked brand-new because the owner would polish & wax it on a regular basis, but would never grind through those thick layers of clearcoat. Probably overkill for a speaker project though ;) Watch some videos to get an idea of what the clearcoating process looks like.

                      6. Wax coat:

                      If you want to wax it (and if you've done a lot of work on the clearcoat, it deserves a wax job!), wait about a month for the paint to outgas. There are two kinds of wax available - synthetic and carnauba. The secret to getting an amazing finish is to use *both* :D If you've ever been to a car show where they have ridiculously shiny cars, this is the trick they use. First, you put a layer of synthetic wax on, which acts as the glossy layer. Let that dry (ah, "cure") for 24 hours. Next, put 2 layers of carnauba wax on - put the first layer on, wait 24 hours, put the second layer on. This adds depth and gives the finish the traditional car wet-look finish. So 3 days total for the wax coat, 30 days after you paint to allow for outgasses. It's hard to wait, but the results are worth it. No one will have a clue you use spray paint!

                      If you want to mess around before you wax, you can also try polishing it (SwirlX is popular, or Ultimate Polish). I have seen claybars used on MDF too. You end up with a great finish. None of this is really expensive or anything, just takes some time & patience. Although again, you can go nuts with this - if you're doing a gorgeous black finish, P21S carnauba wax is the way to go for dark/black colors (starts at $33 a tub though...).

                      Notes:

                      I'm sure I left a couple things out, but you get the idea. If you give it the proper time (really a month or two) and do all the steps, you can get pretty ridiculous results from spray paint. Mostly it's just tedious - nothing's really hard, just a bit time consuming and a lot of steps, and then it feels like you're waiting forever. You can get a better idea of how the process works by watching some Youtube videos. You can also google for "spray paint a car" or "spray paint arcade controllers" (people who do DIY joystick controls do really great clearcoat & paint work!). Again the biggest frustration is not committing to doing it right by spreading out the steps over time. If you rush it, you'll risk ending up with a crappy paintjob and you'll have to start all over again (which I've done and is just about enough to make you throw up haha). Anyway, here's some starter links:

                      http://www.caraudio.com/forums/enclo...spray-can.html

                      http://shoryuken.com/forum/index.php...worklog.67501/

                      http://www.diyaudio.com/forums/const...ishing-35.html

                      As far as the paint schedule goes, about a month and a half total if you want to get serious about it:

                      Day 1: Smooth coat (wood filler) - 80/120, 200/300 grit sanding
                      Day 2: Seal coat (2 coats) - 200/300 grit sanding

                      Day 3: Prime coat (2 coats) - 200/300 grit sanding
                      Day 4: Prime coat (2 coats) - 200/300 grit sanding

                      Day 5: Color coat (2 coats) - 300/600/800 grit sanding
                      Day 6: Color coat (2 coats) - 1000 grit sanding
                      Day 7: Color coat (2 coats) - 1000 grit sanding

                      Day 8: Clear coat (2 coats) - 1000 grit sanding
                      Day 9: Clear coat (2 coats) - 1000 grit sanding
                      Day 10: Clear coat (2 coats) - 1000 grit sanding (tack cloth/alcohol for cleanup)

                      <wait 30 days for outgassing>

                      Day 40: Wax coat (optional claybar/polish, synthetic wax)
                      Day 41: Wax coat (carnauba wax)
                      Day 42: Wax coat (carnauba wax)

                      Initially buying all the stuff can add up...wax, paint, wood filler, etc., but you usually get enough to last through several projects (aside from the paint colors and clearcoat specifically for the project at hand). Try it out on a scrap piece of wood to get a feel for it and see how you like the results, and to develop your own procedure. HTH.

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                      • #12
                        Re: A question for rattle can gurus....

                        If you want it super shiny, you don't need to worry about a gloss coat of paint then clear. The clear gives the shine, the base (colour) coat does not. Make life easy, prime with a dark gray then prime with black. Use the dark gray as a guide coat to make sure the black layers are even. Black primer wet sands (or even dry sands, but why dry sand, it's a waste of sand paper) way, WAY, easier than gloss paint. Keep applying thin layers of primer wet sanding between. Get the black primer so it's even in colour and without pin holes or "chips". Sand up to 800. Drying in direct sunlight on a hot day is a great way to crack your corner seams. Don't do it. Opt for some shade.

                        Once the box is super smooth in black primer start appling THIN coats of gloss... don't get excited and get runs, it's a waste of time and work. Apply 4-6 thin layers of clear and let dry. Then wet sand. 600 in sets to 1200. Most likely you will see pin holes. Sand them down but don't worry about getting them out on the first round. I'd sand with 600 for the first application. Clear a few more layers, wet sand with 600 then 800. Apply some more clear, sand 800 and 1200. Look it over, if all pin holes and orage peel are gone then start buffing.

                        ALWAYS USE A SANDING BLOCK AND WATCH THE CORNERS (I like to spray the corners and edges first on every pass, build them up a bit)

                        here is a sub I did http://techtalk.parts-express.com/sh...ghlight=cerbus
                        all spray cans. Looks good, hiding behind a cupboad :rolleyes: I'd give the whole process 10 days, 1-2 hours a days.

                        Here is an example of the shine
                        Click image for larger version

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                        • #13
                          Re: A question for rattle can gurus....

                          As a motorcycle show nut, IF you have a strong arm, monton wax is even better a deeper looking than carnuba, but it's hard to find and expen$ive. Mother's Show Gold is monton, and you wipe it off with terrycloth, then buff with a chamois (and buff and buff and buff and buff....) The multi-million dollar cars at the Leake Auction are all polished with monton, especially the older "classics". It's not as "glossy", but it has a deeper "luster" which looks much more classy than a mirror finish. George Harrah's Dusenburg boat-tail chopped roadster that belonged to Clarke Gable that was shown at the Leake Auction this year, had that "luster" look as did all the older Rolls-Royce's and Caddies and V-12 Lincoln's and LaSalle's and big Packard Twin-Sixes. The little 256 Ferrari (Pigeon Blood Red) had the same "look three feet down into the paint" look.

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                          • #14
                            Re: A question for rattle can gurus....

                            An update on my progress: based on some of the things mentioned above, I decide to give Duplicolors Acrylic Lacquers a try. I've never worked with lacquers before so I figured I might as well get familiar with them. The gloss black base coat went down reasonably smooth although I feel like Duplicolor tips don't merit the bragging they do, they were hit and miss with these cans. Once the base was dry I laid down a few coats of Lacquer clear and after 24 hours dry, my god does this scratch easily! I knew lacquer was fragile but all I did was wipe off some dust it seemed to attract easily with a microfiber towel. I'm going to wait a week, and polish with some compound and see how it turns out on these two pieces before moving on to the speakers top pieces (these pieces are two lower pieces that will not be easily visible).

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                            • #15
                              Re: A question for rattle can gurus....

                              In all fairness, the duplicolor tips are far better than what Rustoleum gives you. They're certainly no equal to a compressed air HPLV sprayer, but they are an order of magnitude easier to use than the tiny cone of spray that lesser tips give.
                              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                              95% of Climate Models Agree: The Observations Must be Wrong
                              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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