After spending countless hours building a portable and working on your case, the final step before assembly is painting. A good paintjob goes a long way in making your portable look nice, so it can be frustrating when your paint doesn’t come out right. Hopefully this guide will help with finding out what may be causing your issues if you are experiencing trouble getting a nice finish on your project.
Before painting:
The best way to ensure a good paint job is to use a test piece. When painting your case, paint a scrap piece alongside it. You can scratch your test piece to see how dry it is without worrying about messing up your case. It’s a good idea to make another test piece using the same exact material as your case before painting your case to make sure it works right.
If you do experience issues with your paint, hopefully this guide will cover it. If the problem persists, it may be due to the paint. Your paint must specifically say that it works on plastic.
Bubbles:
The first thing you should check is your nozzle. If it has a buildup of paint around it, clean the nozzle off and then test paint on something.
If you are putting too thick of a layer, it can cause bubbles. You should be moving the can as you spray. Try moving the can farther away from your object while spraying. Start spraying to the side of your object, then pass over it completely before stopping the spray.
Wrinkles:
Wrinkles are usually caused by paint drying oddly as you spray.
If you are painting outside on a hot day in direct sunlight, that might be your problem. Weather can affect paint in odd ways, so it’s best to paint in the shade on a non-humid, non-windy day.
Putting too many layers in a short time period can make the paint wrinkle. Usually paint cans recommend applying additional layers within a few hours or after a day or two.
Putting too thick of a layer can also cause wrinkling in your paint. If it looks like your layer is thicker than a sheet of paper, you’re putting too much on.
Rough Texture:
If your paint has burrs, it could be from spraying from too far away. Try moving closer to your object.
Sanding lightly with a very fine grit in between layers can get rid of any burrs the paint develops.
Make sure it’s not windy or hot while painting.
Paint Is Soft/Won’t Dry:
The biggest reason for your paint not drying is applying too much at one time. It could be that you are applying a couple thick layers instead of many thin ones, or that you have too many layers overall.
How long has it been since you painted? I usually give my projects about a week to dry after completing before assembling. If it’s only been a day, your paint should be dry to the touch, but not completely solid.
If it’s automotive paint, it will take much longer to dry fully. “Regular” paint like Krylon Fusion and Rustoleum should dry within a week if used correctly, but certain paints can be very slow to dry.
Make sure you are drying your paint indoors or in a climate controlled area. If you live in a humid area and are trying to dry your paint in a humid garage, it can take longer to dry or not do so correctly.
Pieces Sticking Together:
If you are painting two pieces of plastic that are meant to be touching but still move, such as a battery cover, sometimes the pieces will stick together. It might be difficult to remove the battery cover if your object has been sitting a while. Sometimes forcing the parts away from each other can cause one piece to pull bits of paint off the other piece.
This is caused by putting the pieces together too soon after drying. Even if your paint appears dry enough to assemble, putting it in contact with other painted pieces can cause the paint to bind together (sometimes stronger than the bond from the paint to the plastic). The only way to avoid this is to allow more time for the parts in contact to dry.
Paint Won’t Stick:
Sand your surface. If it’s too smooth or has a polish on it, sanding can rough it up and give the paint a texture to stick to.
Use primer. Primer can be used to make your object an even, neutral, color for painting, but it can also help your paint stick to trouble surfaces.
Is your paint made to work on plastics? If it doesn’t say, it’s better not to use it.
If all else fails, try a different paint. I have found Tamiya brand to stick well to difficult surfaces.
Something Got in My Paint:
Paint will not fill holes, so if you have an indentation, your best bet is to let the paint dry and then sand it down around the affected area before repainting.
To prevent this, paint up off the ground. Dirt won’t usually be blown very high, so painting on a platform will reduce the number of things that get in your paint.
If there’s a breeze, paint inside of a box on its side. I use a storage bin to shield from wind on three sides.
Dry your object inside. Garages have more bugs that could get into your paint than indoors. If you can’t dry your parts inside, at least let the very top layer dry before putting it outside so it will be resistant to imprints from flies and dust.
Before painting:
The best way to ensure a good paint job is to use a test piece. When painting your case, paint a scrap piece alongside it. You can scratch your test piece to see how dry it is without worrying about messing up your case. It’s a good idea to make another test piece using the same exact material as your case before painting your case to make sure it works right.
If you do experience issues with your paint, hopefully this guide will cover it. If the problem persists, it may be due to the paint. Your paint must specifically say that it works on plastic.
Bubbles:
The first thing you should check is your nozzle. If it has a buildup of paint around it, clean the nozzle off and then test paint on something.
If you are putting too thick of a layer, it can cause bubbles. You should be moving the can as you spray. Try moving the can farther away from your object while spraying. Start spraying to the side of your object, then pass over it completely before stopping the spray.
Wrinkles:
Wrinkles are usually caused by paint drying oddly as you spray.
If you are painting outside on a hot day in direct sunlight, that might be your problem. Weather can affect paint in odd ways, so it’s best to paint in the shade on a non-humid, non-windy day.
Putting too many layers in a short time period can make the paint wrinkle. Usually paint cans recommend applying additional layers within a few hours or after a day or two.
Putting too thick of a layer can also cause wrinkling in your paint. If it looks like your layer is thicker than a sheet of paper, you’re putting too much on.
Rough Texture:
If your paint has burrs, it could be from spraying from too far away. Try moving closer to your object.
Sanding lightly with a very fine grit in between layers can get rid of any burrs the paint develops.
Make sure it’s not windy or hot while painting.
Paint Is Soft/Won’t Dry:
The biggest reason for your paint not drying is applying too much at one time. It could be that you are applying a couple thick layers instead of many thin ones, or that you have too many layers overall.
How long has it been since you painted? I usually give my projects about a week to dry after completing before assembling. If it’s only been a day, your paint should be dry to the touch, but not completely solid.
If it’s automotive paint, it will take much longer to dry fully. “Regular” paint like Krylon Fusion and Rustoleum should dry within a week if used correctly, but certain paints can be very slow to dry.
Make sure you are drying your paint indoors or in a climate controlled area. If you live in a humid area and are trying to dry your paint in a humid garage, it can take longer to dry or not do so correctly.
Pieces Sticking Together:
If you are painting two pieces of plastic that are meant to be touching but still move, such as a battery cover, sometimes the pieces will stick together. It might be difficult to remove the battery cover if your object has been sitting a while. Sometimes forcing the parts away from each other can cause one piece to pull bits of paint off the other piece.
This is caused by putting the pieces together too soon after drying. Even if your paint appears dry enough to assemble, putting it in contact with other painted pieces can cause the paint to bind together (sometimes stronger than the bond from the paint to the plastic). The only way to avoid this is to allow more time for the parts in contact to dry.
Paint Won’t Stick:
Sand your surface. If it’s too smooth or has a polish on it, sanding can rough it up and give the paint a texture to stick to.
Use primer. Primer can be used to make your object an even, neutral, color for painting, but it can also help your paint stick to trouble surfaces.
Is your paint made to work on plastics? If it doesn’t say, it’s better not to use it.
If all else fails, try a different paint. I have found Tamiya brand to stick well to difficult surfaces.
Something Got in My Paint:
Paint will not fill holes, so if you have an indentation, your best bet is to let the paint dry and then sand it down around the affected area before repainting.
To prevent this, paint up off the ground. Dirt won’t usually be blown very high, so painting on a platform will reduce the number of things that get in your paint.
If there’s a breeze, paint inside of a box on its side. I use a storage bin to shield from wind on three sides.
Dry your object inside. Garages have more bugs that could get into your paint than indoors. If you can’t dry your parts inside, at least let the very top layer dry before putting it outside so it will be resistant to imprints from flies and dust.