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Repairing orange peel paint defect

March 8th, 2009 · 7 Comments

Following “Scooter and Motorcycle AirBrush Painting – doing it the right way” , on this article I will talk about how to repair a paint defect, or what’s known as “orange peel” paint defect.

Incorrect air brushing (lack of air pressure, too little spraying or too fast), will sometimes result in a surface with small dimples on it, very similar to how orange peel looks. Anyway, that’s something you can’t hide, and there is a way to repair it, assuming the top layer of clear coat has enough of “meat”. If it was two layers of clear coat, then most likely you have enough coat thickness to work with.

To know how to do things right you sometimes need to make mistakes. And this is how I was able to write this article. My first coat turned out good, but an unexpected delay, made me spray the second coat two hours later into the evening. I wasn’t prepared for evening time, so the lack of sufficient light, made it hard for me to see clearly, causing some areas to have an uneven coat.

Just a warning before we start – do this procedure only after a few weeks when the clear coat/paint is 100% dry. Don’t try to sand paper the paint the following few days right after the paint job, or you are risking cracking or smudging the paint.

The simple solution is to water sand the paint. That’s right. What we want to achieve is a smooth surface and that can be done only if we water sand the clear coat until all the dimples are gone. How do we know they are gone? As soon as we’ll start water-sanding the area, the dimples will turn to be more noticeable, cause the inside of each dimple will remain glossy while the outer part will turn matte from the sanding. As we proceed with the sanding and work deeper, the dimples will get smaller and smaller until we are left with a smooth matte surface.

To get the paint to shine once again, we need to polish the surface with a very fine polishing formula. I used RIWAX® RX 04 (“FINE”) to get the vespa paint shining again, it is liquid wax mixed with fine abrasive particles. Do not use a regular rubbing compound in those small metal cans, it is way too coarse and thick for this job.

This is the magic stuff. It is also good for just a polish to remove tiny scratches, renewing faded paint, etc.

Ok, so we went over the theory, let’s get practical. For that you will have to prepare:

  1. a half filled bucket of tap water, with a few drops of liquid soap for dishes
  2. five waterproof abrasive paper P2000 (super fine) and five  P1000 (fine). If you have ugly clear coat drips you want to work on, maybe get a few P800 paper too. (these quantities are an estimate for a fairly good paint on a Vespa sized scooter. If you have a ford mustang…you’ll need a few more..)
  3. a rectangular shaped (about 2X4 inch) flexible but thick rubber
  4. sponge or kitchen mop

Cut the abrasive paper, that usually comes in A4 size (that’s a standard size of paper you put in your home printer) , into 4 pieces. Soak them all in water for at least a few minutes before use. It is ok if you keep a few quarters in the water until use.

Start with one square of the P1000, and wrap it around your rubber rectangle like shown:

Making our “tool” – Just a piece of thick rubber wrapped with the sand paper.
Work with the smooth side of course, not the side that has the fold – in photo #2 that would be the down side. There are some tools that hold sand paper – they are made of hard plastic, that is not good for this job. Foam will be too soft, don’t use it too. You need the sanding side to be strait and firm, yet with the ability to bend a little, adopting itself to the contour of what you’re working on.

The steps are:

  1. Using the (rubber) tool, will insure surface will be sanded in a uniform manner , without the risk of sanding one area more than the other. Furthermore it’s more easy like this. Try to apply uniform pressure on all the tool, while sanding in a back and forth motion. Make sure the water paper is always wet. you can use soaked sponge and splash water on it, or just dip the sanding tool in the bucket of water. If it seem to weaken or wear, use a new square of sand paper.
  2. Just a bit before the dimples seem to be 75% smaller, start using the finer P2000 paper for your final sanding. Stop sanding immediately when you reach a matte but dimple-free paint surface. Be careful not to over do it, cause in this stage you haven’t got much clear coat thickness.
    Now, you may be tempted to use only the P1000 or P800, which are more coarse and will remove clear coat half the time – please don’t – they will leave too deep scratches (simply – tiny grooves) the polish won’t be able to remove, resulting in a dull finish. On the contrary, you CAN work just with the P2000 or even a 3000 paper , but those super fine sanding papers, will take you a LOT of time getting the dimples off, not to mention paint drips that have lots of “meat” to sand.
  3. Areas you should take more caution are edges and curves. While sanding these areas you should take consideration you are naturally putting more pressure on the edge or curve, risking in getting beyond the clear coat faster than you thought , damaging the underneath color coat, so stay alert and don’t work on one spot for too long. Again, the best way is to sand a bit, stop, wipe the area with the sponge or kitchen mop and asses your progress.
  4. If you are dealing with drips, you can use a coarser sand paper, maybe P800, and use your finger to apply pressure on your tool only on the drip itself, until it almost disappears and becomes uniform with the surrounding surface. At this stage continue sanding with a finer P2000 paper until the drip disappears and you have a smooth area.
  5. Now, if you made it to this stage alive, here is the fun part: take a big cotton ball or a very fine small towel, put an olive size RX 04 compound on the paint surface OR on your towel, and start buffing small areas, one at a time, in a back and forth motion.
    After a few back and forth motions – viola! you will start to see the paint shine again, but now, without the ugly orange peel dimples, just a clear shiny surface as you intended it to be. Continue until satisfactory and uniform shine builds up in the surface. Of course you can use a buffing machine if you have one.
  6. You can now wax your scooter or motorcycle and be proud!In any case, follow this manual, only if you feel comfortable with doing the job (and of course at your own risk). I have no idea how good and thick your clear coat is. You can try repairing a small area, and see how it goes. If you see you can handle it, continue.
    Always be alert, see how much you sanded. That’s it – good luck!



Tags: Crafts · Motorcycles & Scooters


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