How to Paint Metal so The Paint Doesn’t Flake or Scrape Off

Difficulty: Moderately Easy

Instructions

Step 1

First you need to get the right paint. Brushing paint onto metal never works nearly as well as spray painting it when it comes to a smooth coat so that’s what you’ll need to use. Paint doesn’t stick to metal very well though so you’ll need to put down some primer first. Go to your local hardware store and look for a spray primer labeled “auto primer.” You’ll see that it says it’s safe for basically any metal surface, not just cars, despite the name. It works as well on your fender as a plate of sheet metal. Make sure you pick the primer color closest to the paint that’s going to go over top of it. If it’s a dark color, choose black primer for example. I like Rustoleum auto primer because I’ve used it before and everything about it is great. Also most have a rust preventing ingredient. If you’re painting something that can rust like iron or zinc, you’ll definitely want to use primer with rust prevention. If you’re painting aluminum, you don’t need it though.
Step 2

While you’re at the store, you might as well pick up the spray paint at the same time as the primer. For the best results, pick a paint that’s the same brand as the primer because they’re made to go together. So put Rustoleum paint over Rustoleum primer for example. Also, putting regular paint over automotive primer will work better than paint alone but still not as well as using actual automotive paint. Right next to the auto primer should be all the auto spray paint. Keep in mind that if the metal surface gets hot, you’ll definitely need automotive paint rated for high temperatures. Usually the heat safe paint is titled engine paint or exhaust but works on any hot metal, not just car parts.
Step 3

Now that you have what you need, prepare an area to paint. Make sure that you’re in a well ventilated area. Read the back of each can of spray paint to see what temperatures and humidity levels the paint can be used in. Usually it’s 50-85F at 80% or lower humidity but it varies by brand. If it’s too cold, don’t close the room up tight and start up a heater because the fumes are flammable and the heater may ignite them. If it’s too hot, the paint will dry too quickly which is bad for long term adhesion so you should wait for night time when it’s typically cooler. Put down plastic painters sheeting to protect anything you don’t want particles blowing onto. Also make sure there’s no free dust, dirt, or other particles in the air that will settle on the wet paint while it’s drying.
Step 4

Now that the location is set up, prepare the metal for painting. All you really need to do is wash it with dish soap and water then dry it thoroughly so you have a nice, clean surface for the paint to stick on. You do not need to rough up the metal with sand paper but if there is existing paint, you’ll need to remove it that way or with paint thinner. Use proper breathing and skin protection if the old paint may be lead based.
Step 5

Now you’re ready to start painting. Coat the entire piece in one layer of auto primer. You’ll notice that the difference between normal spray primer and automotive/metal spray primer is the thickness of the paint. It’s more like spraying sticky tar on the metal than liquid paint. It also dries to a thinner, more powdery looking layer instead of the thick, sticky looking enamel that normal spray paints look like. You should have no problem coating the entire piece without the paint rolling off or even moving at all.
Step 6

Since you’re using primer and paint, you really don’t need two layers of primer. If it looks spotty though, wait for it to dry then apply another layer. Read the back of the can to see how long you should wait for the primer to dry before it’s considered “paintable.” Usually it’s an hour or less. Once it’s had that time to dry, get out the spray paint. Spray it the same way as the primer and make sure you apply a very even coat. Since this is the top coat, you’ll want it to look really good. Try to put down a very even, non-spotty layer of paint on the first coat so you don’t need a second one. Multiple coats make the paint more likely to flake or scratch off.
Step 7

Let the paint dry on its own until it no longer looks visibly wet. Then give it about 10 more minutes just to make sure it dries naturally then to completely set it, get out a hair dryer. Make absolutely sure that the propane distillates used to propel the spray paint have cleared out of the air so you don’t blow yourself up then turn it on maximum hot and blow it on the metal. After just a minute or two, the metal should be extremely hot to the touch. Be careful not to burn yourself. Once it is, stop blow drying it and let it cool down slowly in the air. Heating it up this hot once it’s already mostly dried will cause every tiny bit of moisture to evaporate resulting in a very dry, hard, thin layer of paint that is extremely tough. I used this exact process on the dust caps on my brother’s car after the factory paint flaked off and the metal rusted. My paint job paint has held up better than the factory paint now, a year later. It still looks like the day I painted it and that’s after a hot summer and below 0 winter so if you follow this exact process, you’ll be very satisfied with the results.

Comments

williamfjordan said

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on 2/24/2009 nice article ... 5*

copperhill said

on 2/10/2009 Just in time for spring. We have some vintage metal lawn furniture and I need to get them spruced up. This article was a must for us.

bethjess39564 said

on 1/9/2009 Primer is so important! Always prime or you'll only have to re-do the paint next year. Great advice.

WolfTech said

on 1/3/2009 Good article desolator! I have an old metal computer case laying around in storage, maybe I'll give it a new paint job and build a system in it! lol