When you haven’t spray painted much, if at all, it can feel a little intimidating. You have this spray paint can in your hand, and you’re thinking, “Okay, don’t mess this up. Spray from this distance, and spray across the model at this speed. Okay, I think I’m ready.” It’s not like painting with a paintbrush because the paint can is basically on or off. You’d better have good technique or you could end up with a crappy paintjob. Here are some tips for spray painting models so that you go in armed with some knowledge.
Tip 1: Practice and Safety
Of all the tips for spray painting models, this is the most important. Get a piece of cardboard, paper, old plastic or metal, and paint it. Paint it and every other piece of junk you find (as long as you own it), to your heart’s content. Feel what it’s like when you spray at different distances and sweep the can back and forth at different speeds. Pay attention to see when there’s not enough paint and when there’s too much and it starts to run. See how the paint bonds or doesn’t bond to different surfaces, to clean and dirty surfaces (hint: paint doesn’t bond very well to dirty surfaces), and how the material’s texture is changed after painting. As you do this, be aware of overspray and ventilation, and be sure to wear a good paint mask. You don’t want to inhale this stuff, and you don’t want to practice on top of your kitchen countertops. Also do not spray near flames or sources of heat because this stuff is flammable. I typically go outside and use a cardboard box as a makeshift spray booth whenever I do anything like this. You should also wear latex gloves so you don’t get paint all over your hands and fingers (it’s common to get paint on the tip of the finger that’s depressing the nozzle) and you should wear clothes that aren’t very important to you in case you get spray paint on them.
Tip 2: Prepare and Clean the Model
When you feel you have enough practice, don’t paint your model just yet. Make sure it is free of any defects and that it is clean. To free it of defects, such as seams left over from the injection molding process, simply take a sharp knife or fine-grit sandpaper and gently shave or sand the offending area such that it fits the contours of the part. If the part is glossy, lightly scuff it with sandpaper because paint doesn’t bond very easily to glossy surfaces. Now you can clean the part. There are products available that are specifically made for cleaning model parts before painting, but I rarely use those. I’ll simply use rubbing alcohol or warm, soapy water (be sure to rinse the soap off and make sure the model is dry before painting). You want to clean your model because you want to remove such things as dust or oils left over from the manufacturing process, or even from you touching the part. Speaking of, once you clean the model, avoid touching it. Handle it from surfaces that aren’t important (such as the interior of a model car body) or use latex gloves.
Tip 3: Secure the Parts
Spray painting essentially involves blasting a surface with paint-filled air. That’s why it’s important that you secure your part, especially if it’s small. There are several ways to do this, the only limitations being your ingenuity and what you have on hand. A few tips are to suspend the part using string, use double-sided tape or a loop of tape to secure a piece to a surface, or create stands out of wire for spray painting your models. I’ve even heard of people using super glue to glue straws to noncritical surfaces (a surface that will eventually be covered up as you assemble the model) and holding the part by the straw as it’s painted. Whatever you do, be sure it’s something that won’t cause permanent damage, and be prepared for later touch-ups. For example, if you used a string to hang your part, you’ll have to touch up where the string covered. If you decide to tape a part down that will require paint on both sides, after you’ve painted one side, you’ll need to remove any tape residue from the other, and when you paint the second side, you’ll have to secure the part again using tape that won’t affect the painted side (any decent masking tape should work just fine).
Tip 4: Warm the Paint
Spray paint works better when it’s warm. If it’s already a warm day, you probably don’t have to worry about doing this. If it’s not, place the can in a bowl or glass of warm tap water and let it sit there for a while. Don’t get the water too hot by using a stove or microwave and do not submerge the can. The can does not have to be hot, only warm. Dry the can off thoroughly once it’s warm. Above all, do not heat the can on the stove, in the oven, in the microwave, over a fireplace… Doing such can cause the can to explode.
Tip 5: Painting
When it’s time to paint, keep the can approximately a foot away from the surface you’re painting. Before you depress the nozzle to begin painting, aim the can so that it’s pointing off of the model. You then evenly sweep the spray back and forth over the model, being sure to cover the entire surface you want painted. When there’s enough paint applied, again point the can off the model and release the nozzle. You don’t want to start or stop painting on the model because doing so can create irregularities on the painted surface. When you’re done painting, turn the paint can upside down and depress the nozzle again. This will clear out paint from the nozzle so that it won’t dry in there and make the can unusable later. Point the can in a safe direction as you do this, and keep the nozzle depressed until paint stops coming out. The nozzle is clear when no paint is coming out. To let the model dry, place it in a dust-free area. If you think a second coat is necessary, you can apply it after about 30 minutes. To let the paint dry completely, let it sit for about a full day. Avoid touching it before it’s dry because semi-dry paint is tacky and can easily pick up fingerprints. To check if it’s completely dry, find an inconspicuous spot on the model and gently press into it with your fingernail. The paint is not dry enough if your fingernail leaves a dent.
Tip 6: Finishes
Improper painting can leave undesirable finishes behind. If the paint is running or dripping, you applied too much paint. This can be caused by not sweeping the can back and forth, or by holding the can too close. If the model was dirty or you held the can too far away while painting, the paint might be rough. A dirty model may also cause the paint to peel, as could painting over a glossy surface. Learning how to get the finish you want is why the practice in Tip 1 is so important.