I think we really need a sticky on spray paints... A compilation of information, methods, types of spray paints, techniques, pin striping, etc...
Afterall, these are what some of us use to make a nicely finished case.
When sanding or spray painting, it is vital to be in a well vented area and always use a face mask so you don't inhale any dust.
It is also advised to have protective eye wear to prevent any dust particles from going in you eyes.
To prepare the surface, thoroughly sand using medium to high (200-500 ish) grit sand paper going in a circular motion to prevent large noticable lines from appearing on the surface.
Whether you did wet or dry sand, get a clean damp cloth and clear all dust from the surface, and let the surface naturally dry.
(ShockSlayer:) If the surface is plastic, wash thoroughly with water and scrub it with dish soap before painting.
Whilst it's easier to spray in just one colour, picking multiple colours to compliment eachother is a skill to achieve the final design you want.
The easiest way to do this is to use colours on the same side of the spectrum, where white and black goes with everything.
(i.e, different shades of blues, different shades of red, etc.. )
Other colours do go together nicely, but it's a case of mixing and matching to get your desired effects.
One final tip. Don't rely on the lid of the spray paint for an accurate colour. Although they are close to what they will be, they are not exact. If there is a tester, try that first. It's always worth picking your colours on computer and printing it out to take as a reference.
Before applying the spray paint, do a test on a scrap piece of plastic to ensure the spray paint isn't blotchy as this can ruin your surface immediately.
Test the spray paint before each use as used spray paint is more likely to cause blotchiness than new spray paint.
If new spray paint causes it, get a refund (may be worth keeping your receipt).
Clean the nossle after every use by turning the spray can upside down and spraying until just air comes out (2 seconds).
Get a large piece of scrap cardboard and do this in a well vented room with a controlled atmosphere. If you're going to do this outside, make sure it's a nice calm or sunny day, not windy. Rapid changes in temperature can crack the paint job as it cures.
Spray a thin coat from around 30cm away from the surface, and go left to right in an even paced stroke.
Don't go over the same area twice in one go.
Don't aim to cover the whole surface in one go. It can take up to 7 applications of primer to cover the surface, or 5.
Doing it in any less can cause primer build up or pooling of paint, or even drips, which will take you back to step one.
Leave at least 30 minutes after applying primer before handling.
Between applying primer, lightly sand the surface with a medium to high grit sand paper (200 - 500) going in a circular motion. Don't strip off all of the primer that you applied.
Remember to use a damp cloth to remove any dust.
Repeat as necessary until the whole thing is covered.
Painting all depends on the finish you're going for.
As with the primer, apply thin coats, but leave around one hour between handling and sanding.
Start with a high grit sand paper (500), wipe off any dust with a damp cloth, apply another coat, and progressively sand using an ultra high grit (max 2000 grit), until you get a perfectly smooth surface.
When ready to apply the final coat, use some tack tag (which can be found at your local auto shop) to remove any dust particles that are too small for a damp rag or cloth to pick up.
After applying the last finish coat, do one more light sand with the ultra high grit sand paper, to get the surface nice and smooth and leave the surface to cure for about a day.
The surface will be smooth and has a matt finish with no bumps.
Next, take some rubbing compound and give the surface a thorough rub. This will start to bring out the final colour.
Repeat this until you can't get any shinier.
Next, switch to a car waxing compound, and keep rubbing away..
After a few hours you'll have a nice mirror to your paint job... This may take a few days.
I recommend leaving the surface for a further 5 days to let the paint fully cure before handling it.
I recommend using metalic paints for best effects, although these do cause issues with direct reflectivity from the paint work, but the surface will be mirror finish.
Don't use chrome spray paints. Although you'd expect to get a perfect mirror finish, they can take up to 2 weeks to cure on each application, and are easy to create pools of paint with.
Solid colours make better reflections.
If the final coat is matt finish spray paint, you may want to apply some lacquer after buffing up the matt finish, and then buff the lacquer up to give it a better finish.
Do not use any electric buffing tools, as this can cause the paint to strip off and gloop and ruin the finish.. Do everything by hand.
This is quicker, since sanding between coats isn't really necessary. The surface will be slightly textured giving it a matt finish, even if using glossy paint, it will still be textured.
It's good for hiding marks and impurities in the surface.
Metalic paints can be used but will give a satin effect, which does look nice.
Satin lacquer can be used to protect and mask noticable impurities in the final coat.
Alternatives for painting plastic:
There are alternatives to painting plastic that do not require much preperation or priming.
Vinyl based paints, such as the Krylon brand can be designed to cure the spray paint colour directly into the plastic, making the paint very chip resistant.
Do a light sand on the surface to help the vinyl dye adhere to the surface.
Remember to wash the plastic thoroughly with water and dish soap before painting.
Apply it in the same manner by applying thin coats, with light sanding between coats.
I recommend leaving approximately one hour between sanding as you may find the vinyl will peel straight off the plastic as if it has done very little.
The curing process can take up to a week. Once the plastic has cured, you can see the evidence using a test piece and cutting it in half, and notice the surface of the plastic has been penetrated by the new colour.
This allows for some deep sanding if required and will retain most of the original paint colour.
Pinstriping can be a tricky job, so a lot of practice beforehand on a sheet of plexi glass or acrylic.
When doing a long straight line, do it in an open area so you aren't likely to bang into anything. Instead of moving your fingers or wrist, move your arm to ensure the line is straight as moving the fingers and wrist can cause waves or mistakes. For added support, you can mask off the area you want to pinstripe to prevent any wavy lines.
Use a vinyl based masking tape as this allows bending and flexibility compared to paper based masking tapes.
Pinstriping dries relatively quickly, but wait at least 20 minutes before going over any cross over point.