After going through all the work up to this point to get everything as perfect as you can so don’t get lazy here as a little more extra care will make sure that your paint job will be done right. The first thing you need to do is read the recommended direction on the product you will be using. Yeah, I know who reads this stuff but you can learn some important information like what is the best weather conditions to get the best results and such. Normally you will want a day that is about 70-75f and with none to a calm wind if you are painting outside. You also want to avoids days that have high humidity as the metal could collect micro water bubbles and the paint will not adhere or peel and it will cause you to start all over again
A good “self-etching” primer creates the needed layer between the surface and the paint. You see primer is a very key part of the painting process. This gives you a surface that the paint can adhere to rather than directly to the metal. Yes, you can paint right onto the metal but the primer will also help you hide any of the imperfection. Any minute scratches will be filled in by the primer thus creating a smooth surface. Too take this step even farther and help you get that glass smooth finish you need to do some wet sanding on the primer. Wet sanding is pretty much as it sounds. Using a liquid and some wet rated sandpaper, sandpaper that stays together even after extended use with water, you sand…err maybe a better word would be polishing the surface to a smoother finish. This process gives you the best results when done a few times. To do your wet sanding we need just a few items such as water, sandpaper, and an area that will be OK getting wet.
Apply your first coat of primer and let it dry completely. I like to make sure that my first coat of primer is left to dry for at least one full day or longer. If the ambient temperature is below the recommended one stated for the product then you might want to wait for a warmer day or find a place that the item can dry in that is warmer. Doing this will ensure that a good bond will be created between the primer and the metal surface. Plain water is used as your liquid to sand with and I like to add a few drops of liquid dishwashing soap into the water as it seems to make the area more slippery and helps clean the surface. A bowl, tub, garden hose or whatever you have can be used to hold or supply your sanding liquid. Place the wet sandpaper into the solution and start sanding your piece. You do not need to apply a lot force when doing this as you are not trying actually remove all the primer but you are just removing any of the high spots and make it all the same thickness. For those of you that to take a short cut can stop here, but I would really not recommend it. By repeating the above process of primer, drying, sanding you are guaranteed a better surface to paint on which is VERY important.
Another quick tip is to paint the non-important side first. Let us say that you are painting a panel that might get seen from the inside of the case, but the majority will be in plain sight with the rest of the case. Take your time and spray some paint on the less seen side first and thoroughly let it dry. Then start on the more visible side since this is the one that everyone will see. You really do not want to put all your time and effort on the front side and then run the chance of ruining it by having to place it face down and spraying the back and getting overspray all over the finished front side. If you do it the way I said and you get a little overspray on the backside, more than likely it will not ever be seen.
Using your typical spray can of paint you will need to make sure that the paint inside is mixed well. Firmly grab the middle of the can and then shake the can in an up and down motion and within a few moments you should hear the mixing piece “rattle” around, thus the nickname rattle can. Do this for about 60 seconds or more to thoroughly mix the paint. I like to also twist-shake the can from left to right for the final mixing. Take a look at the nozzle location and make sure that it is pointed toward the dot marked on the can. What this does is to ensure the when you slightly tilting the can to apply your paint that the pickup tube is always in a spot to put up the paint down to the very last of it.
When you start to apply your paint you should always start with any of the edges; have it be the edge of a window you made or the bent edge of a side panel. These areas will only take a small amount of the paint that the can is releasing which means that there will be a fair amount of leftover paint in the air, better known as overspray. This overspray will carry over on to larger surfaces like the flat spot of a side panel. This is perfectly fine as you have not applied any paint to the flat area of the panel, but if did paint it first and then did the edges last all the overspray could cause to much paint to be on the panel and cause runs in the paint which means that you have to sand down the paint and start the painting process over again. So as you can see it is better to have this overspray happen now when there is no paint on the large surfaces.
Take your spray paint can and point it away from your object and give the nozzle a pushes to force out the paint. This will make sure that the pickup tube is full and that the nozzle is not clogged and is spraying correctly. Once you know that everything is clear and working you are ready to paint. When you start to spray on the paint make sure that you are standing in the middle of the piece and that you have free movement from side to side. Starting for a point off of the item you want to paint, press down on the nozzle and begin to move your arm towards the panel. With a steady even stroke of your arms sweep from one side to the other, keeping the spray can at the same distance away. When you get to the end continue to spray off of the item by a few inches. Yes, you might waste a tiny bit of paint but you are making sure that you have full paint coverage and no need to go back over any areas missed which can cause to much paint to be applied and cause the paint to run. Repeat this process all the way to the end of what you are painting.