How To Paint Steel Using Brush And Roller

Painting steel may seem very similar to painting interior and commercial jobs but there are some major differences. Altho interior painting may seem more detailed Industrial steel painting is much more challenging. Any small mistakes can cause paint failure and rusting due to steel being out in the elements. In this article we will go over the basics step by step to make sure your steel paint lasts many years to come.

Step 1. Clean your surface

The first thing you want to do before painting and repairing the surface is to clean it. Steel is out in the elements around machinery and even birds. You are going to want to Pressure wash it .We recommend scrubbing greasy areas with simple green and washing with a strong power wash system. The main benefit of this is that when you go yo sand you are not rubbing contaminants into the paint you are sanding. Also using high pressure will cause loose paint to fall and chip, giving you an idea how much repairs you need to make.

Step 2. Repair Damaged areas

Starting from top to bottom , Left to right you are going to grind down every chip and rust spot. I personally use just a Dewalt 41/2 inch grinder and use a flapper wheel on it. (click link to check out the corded grinder we use) When you fix damaged areas with the flapper wheel there will be a little bit of rust behind the failing paint. It is critical you chase the rust and make the repair as big as needed. Taking a shortcut to keep repairs small will just cause paint failure sooner than expected. especially outside with temperature changes and rain. Once you are happy with your repair you should feather out the paint with a D.A sander. We use 60 to 80 grit on industrial jobs. You should see no hard edges around repair and feel smooth to the touch. Visually you will see the layers of paint underneath that you have sanded. After you feather out all the repairs now it is time to sand the whole area getting painted.

Step 3. Sand Area Being Painted

Sanding the whole area being painted is very easy with a D.A sander. any brand will work just make sure it is a D.A which stands for dual action. It spins both ways and leaves a very uniform even finish. We personally also use Dewalt for those and we use the old school cord sanders not battery. The reason you will want a cord sander is this can be a very time consuming job. It’s best to once again start top to bottom left to right to get in a good habit. In the trade this called working square which your boss will appreciate to keep track of the progress of the job. The best prep guys leave the steel looking dull and even all the way down the surface. If the paint is shiny and still has sheen it is not prepped enough. Sheen is left on purpose on a finish coat for appearance and to keep things from sticking to it , making it easy to wipe. Your brand new paint job will be useless and all that prep wasted if you do not rough up the paint and take that sheen off. New paint needs to bond too a rough surface and the 60 to 80 grit leaves a nice profile for the paint to stick.

Step 4. Blow down / Clean

By now your repairs should look perfect and the whole surface is sanded evenly. Now is the time to take a blower and blow down all dust and debris off the surface. This makes cleaning so much easier. Same idea as always blow down top down left to right ensuring you don’t spread dust everywhere. This is also your last chance to double check your work and make quick little fixes . To blow down having the most air pressure is ideal. If we have Chicago hoses and an air compressor I will use that but some jobs a small hand blower that runs off a battery is fine. We have a couple Makita blowers in the tool box that run off batteries. they are very convenient when working up high and a lift. Only down side they are a little slower but there is no set up required running hoses or cords. Once you have your dust off wiping down will be easy with a clean rag and some paint thinner. Some thinners are stronger than others . I’m not too picky on which thinner we have to clean as long as the proper thinner is used when it is time to paint.

Step 5. Mix Paint Properly

Finally time to mix the paint. I recommend having one designated person to do the mixing who is familiar with the paint being used. Please read all directions because some paints have 3 parts such as some type of zincs. Most mid coats are and finish coats are 2 parts . 1 part being paint the other part being the cure or hardener. I will give a brief example of how I mix mid coat Macropoxy for the crew the most easy way.

Macropoxy 646 by Sherwin Williams is very common in the industry. It mixes at a 4:1 ratio. First thing I’m going to do is open the can of paint up and mix it for a couple minutes at least until it turns all the same color and heavy paint at the bottom is mixed in. Let’s say the guys need 1 gallon, one gallon is is 128 ounces. I pour 128 ounces in a mixing bucket and then pour it into a paint bucket. Since it is 4 to 1 ratio i simply divide 128 by 4 which = 32 ounces of cure ( part B on can).  This paint takes 10 – 20 percent thinner depending on weather conditions.  A rough guess i add about 15 ounces into the dirty mixing cups we used clean them out with a brush getting all leftover paints and part B into the thinner to pour over our paint. Take your paint mixer and mix for a minute. Follow these steps and read paint directions for a prefect mix every time.

Step 6. Stripe coat/ Cut In

To begin painting we cut in or stripe coat the whole area. You will have just small brush . We use a radiator brush. For a roller you will have only a small 4 inch on you and will be working out of a gallon sized bucket.  A perfect stripe coat not only helps your paint job look better it protects from missing edges and tough to see areas behind bolts. A stripe coat gets everything you wont be able to get later with a 9 inch roller. I like to use my 4 inch roller along the whole perimeter being painted. The brush is for bolt patterns. Brush all bolts and remember to carry a mirror on you to double check the back side. Then take your roller and make a nice 4 inch square around your bolts so you don’t have to worry about it when rolling out the area with a 9 inch later. You also care supposed to paint any welds in your stripe coat before you roll out the whole thing. On bigger jobs with inspectors some may even require you to use a brush on all the welds ensuring no misses also called holidays in the trade.  A stripe coat is done on every coat. So if you are using a zinc primer, Macropoxy mid coat, and a Eurthane finish coat then you will be performing 3 separate stripe coats with each paint used.

Step 7. Roll out  9 Inch

Time to finally roll out the area and make it look perfect. You will want a small extension pole, 9 inch roller and handle, 5 gallon bucket, and paint grid/screen. This is the one part of the job you don’t want to rush. Nice slow and even overlap. Some guys back roll everything some don’t , We highly recommend back rolling everything down in the same direction. Most jobs wont appreciate this extra step but it does pay off. An example is  a giant gas tank we painted there was 2 of them. The one we painted looked smooth as if it was perfectly sprayed the other had dull spots. The reason was the sun reflection bouncing off the different directions the white paint was applied. Following all the small steps given combined make for a high quality job. I typically get 3 or 4 passes with my 9 inch before I back roll the Paint down at 50 percent overlap. On the finish coat is important the all the people rolling are on the same page and the paint mixer is mixing the exact same way all day. The goal is to paint like a robot and have the most consistent finish.

Closing thoughts

Following these steps will lead you in the right direction for the perfect industrial paint job. These are the basic steps and you can go in a lot more depth which we will cover later. Also on industrial paint jobs an inspector will be making sure these steps are done and proper paint is being used.