Before we move on, let's identify the pros and cons of using spray cans to better understand how we can use them effectively. Spray cans are readily available in hardware stores—one of the more popular brand is Bosny. These are cheap and a whole can can last for a whole 1/100 scale Gunpla kit. However, these are industrial-grade kits and are not primarily designed for scale models. There are also model-grade spray can available in most hobby shops—the most popular brands are Tamiya and Mr. Color. These are more ideal for scale models but will cost more.
Spray cans do not require tedious cleanup. After you consume a whole can, simple dispose it properly—as opposed to using an airbrush, which you have to clean after each batch of painting or when you change to another color. However, you are restricted by a spray can in terms of precision and the higher consumption rate makes it more expensive than airbrush paints.
Whether you prefer using industrial-grade or model-grade spray cans. Always to remember to wear a mask to prevent you from inhaling paint fumes.
Tip 1: Agitate the Paint Thoroughly
Usually, the instructions on the label tell you to shake the can for 30 seconds. I find it more effective to shake the can rigorously for at least a minute to thoroughly agitate the paint. This causes the paint to become smoother and allows it to fluidly pass through the nozzle when spraying. This produces a consistent spray of mist what will give you even coverage.
Tip 2: Test the Spray
Don't be too excited to start spraying on your kit. Do a spray test either on the air to see if you get a good mist, or on a piece of plastic, such a plastic spoon to see if you have a good, clean coverage. This also unclogs blots on the nozzle, especially on previously used spray cans. Your initial spray can cause these blots to stick to your kit.
Tip 3: Maintain Proper Spray Distance
Spray cans usually have a higher air pressure than what is recommended for model kits, which is 15-20psi. Industrial grade spray cans from hardware stores contain an air pressure of about 80psi. This is because the paint is thicker since they are intended for industrial use—usually, car paints. Model grade spray can usually have a pressure of up to 30-40psi, which is closer to the ideal pressure for model kits, and the paint is thinner. When you start spraying your kit, make sure that the spray can is at least 30cm away from the part that you are going to paint. This ensures that the right amount of paint is applied to your kit.
Tip 4: Use a Sweeping Motion
Don't point and spray. Usually, the initial burst of a spray can is stronger than the continuous spray, which results on a thicker coat of paint. Point you can outside of your kit and then use a sweeping motion—either sideways or vertically, whichever you prefer—across your kit while spraying to make sure you get an even coat.
Tip 5: Spray Thin Coats
Don't worry if your first coat of paint is a bit translucent. You can always come back and apply another coat of paint to make the color more opaque. Also, spraying thick coats also endangers your kit's panel lines.
Tip 6: Paint in Batches
Since spray cans contain higher pressure and covers a larger spray area than airbrushes, spray cans consume paint more quickly. Thus, it is not practical to paint each part of your kit individually. Take advantage of the spray can's large spray area by painting in batches.
One way you can paint in batches is by painting your kit while the parts are still on the runner. However, the problem with this is that it will be more difficult to clean up nub marks without ruining the paint. You can use a brush to touch up the nub marks after assembly of your kit.
Another way is use painting clips attached on barbecue sticks. Clip the parts and then arrange the them in a piece of Styrofoam. (I use a block of carton made from strips of corrugated boards stacked together, which is more reusable.) You can then paint the batch of parts at the same time.
