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How To Fix Dry Spray In Paint/color Coat Before Clear Coat? Wet Sand Maybe?

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  • How To Fix Dry Spray In Paint/color Coat Before Clear Coat? Wet Sand Maybe?

    Hey guys, new member here!
    Okay, so I have been respraying an Ibanez flourescent green, and the paint looked magnificent, no imperfections, except for a small dust speck. So, to be diligent, I wet-sanded it out with 600 grit and resprayed for a final coat. Now I have no idea what happened between last night and tonight with the spray can, but as soon as it hit the body, I got immediate dry spray. I waited a few minutes, and then went over it again to see if that would level it, but the can decided to pull yet another abnormality and delivered far too much paint on the resprayed area, in an almost cloudy, ill-mixed blob which resulted in a run.

    So my question is: what do I do to remedy this before starting the clear coat? Should I wet sand with 600 and then 1000 grit and then apply the clear coat after I let the body sit for a few hours? Also, after I wet sand, I tend to get a lot of unwanted cloudy film on the body, even with constant wiping during the process. If I put clear coat over that, will the color coat still have that film on it?

    Keep in mind, one reason I didn't ask about the respraying option is because I've tapped out every supplier in the local area with this one color (only one can per store lol), and respraying with color could mean a week long wait time, which I honestly don't have if I am to deliver my client his guitar with a finished gloss coat by the date we decided on.

    Any help would be greatly appreciated! I have about 24 hours before I can really do anything with the body anyway, I think, so type away!

  • #2
    First I'd need to know what kind of paint you're using.

    The second you need to learn how to read the label. All rattle cans have a message on them that tell you to turn the can upside down and spray when you're done to clear the nozzle. Inside the can is a straw that reaches to the bottom. When you turn it upside down and spray the straw is above the liquid. When you spray it clears the straw with gas. This prevents coagulation in the straw which is what's coming out when you first spray.


    As far as fixing the problem it depends on what you're using. If its lacquer (hopefully) its alcohol based so you have no problem sanding then clear coating over it. Each new layer melts into the previous layer so you wind up with one thick layer. Any other paint or clear coat goes on like layers of an onion. Whatever sanding and scratches you left behind will be visible after a clear coat is applied. You also found out, over spraying defects doesn't hide them. You must ALWAYS, fix the problem before you add another coat.

    You also have to be careful when mixing chemical types.

    There are 4 basic types.

    Alcohol based finishes = Lacquer, Shelac
    Water based = acrylics, lacquers and enamels latex etc
    Oil / petroleum based paints and finishes = Tung oil, True oil, Linseed, Paints, Enamel, varnishes
    Plastic based paints and finishes = Polyurethane, epoxy etc

    Some of these can work together some cant. For example you cant apply poly over lacquer or oils. It will simply peel off like sunburn.
    Lacquers may apply over poly or oils but it can chip off with the slightest ding.

    One of the worst things you can use on guitars is oil based paints and enamels. These paints take years to fully cure and they can be reactivated into a liquid. Oils dry from the outside in and develop a skin. Heat and sunlight can cause them to re-liquefy. I had a guitar that had an Enamel paint job that had been on there 10 years. I left a guitar cord draped over the body when hanging. The vinyl vapors from the wire caused a chemical reaction and the cord melted into the painted finish. (took pictures of it)

    Best thing you can do is stick with the same chemical type when finishing. If you use a lacquer paint, use a lacquer clear coat. if you use poly paints, use a poly stick with poly. The only oils I use are Tung oils and varnishes and I've used poly's too.

    I've heard too many horror stories of people using water based acrylics and lacquers. You're supposed to be able to use them with alcohol based finishes but chemicals are expensive and I've learned it not worth wasting time money experimenting. I stick with finishes that work best on instruments.

    I do like Tung for natural finishes. Its easy to apply and dries rock hard, harder then Lacquer or poly. Lacquer is the easiest to repair which is why its used on instruments plus it feels goo because its made from a resin. Varnish is used on violins. It doesn't shine as much but its sounds best.

    I have used Tung over Lacquer before too. Apparently both contain similar resins which make them adhere well, but Tung does yellow the color compared to lacquer which is clear. I've used it mainly to give maple an antique look.

    Not sure what you're using for paint. I've used automobile paint which comes in various lacquer colors. The only problem with it is it dries super hard and when you get a ding it cracks like an egg shell in chips. Its blended for applying to metal surfaces so it has problems applied to softer woods. The Nitro lacquers sold by places like Reranch or Stuart McDonald are the best for instruments. They also have tutorials on their sites which I recommend reading. Getting a good finish has a high emphasis on preparation. If the body isn't shellacked and sanded to a baby smooth surface before applying paints it will never look professional because paint shrinks to whatever is below. Any scratches will come through and be visible.

    Here's the sites and their tutorial pages

    http://www.reranch.com/products.htm

    http://www.reranch.com/basics.htm

    http://www.stewmac.com/Materials_and...hing_Supplies/

    http://www.stewmac.com/How-To/Online...Finish_Repair/


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    • #3
      What is the exact product that you are spraying? What was your schedule - number of coats, drying time, sanding between coats? Without knowing the type of product it is pretty difficult to give specific advice.

      I general, however, the fix will be letting it cure completely (which may be several weeks or longer), then sanding back all of the problems - runs, dry finish, orange peel - usually starting with 400 or so, then spraying fresh coats on that. You also need to get the color as close to perfect as you can before shooting clear - you absolutely do not want to burn thru the clear back to color.

      Rattle cans makes anybody a "painter" but they have lots of problems as you are learning. They typically have fairly low solids content compared to shooting with a gun, and obviously nozzles plug and you have far less control. I only shoot lacquer (with a gun) and for solid colors I have a professional motorcycle painter who uses two part automotive finishes (and again, uses a gun and controlled spray booth). In general we use the same schedules - correct primer or base for the finish to be used, enough coats to level the surface and allow for perfect color sanding, then the clear coats. With lacquer I never sand finer that 400 grit before applying the clear - you want some tooth for the new finish to adhere to. I also make it a point to shoot two or three final color coats reduced at least 2 to 1 (or more) - these "flow coats" help hide any sanding scratches or imperfections.

      With lacquer I allow 30 days minimum cure time before the final sanding and buff - assuming there are no flaws I start with 1000 or 1200 and go thru the steps to 2000, then buff with medium and fine compounds. Auto finishes, particularly catalyzed ones will have different cure times but don't rush it.

      ps - it sounds like maybe you didn't allocate enough time in your agreement with your customer. Rather that rush it and make matters worse you might want to talk with him.

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