Painting Metal: A Step-By-Step Guide

The rusty look has never been on trend and unfortunately for us, it is inevitable when we have exterior metal structures that are exposed to the elements. If you are a person who enjoys doing small renovations on your own, it's good to know that metal, especially rusty metal, requires specific maintenance if you want to achieve a professional end result.

In order to achieve a job that meets your expectations and that will require little retouching in the future, here are the steps to follow to paint metal properly.

Painting metal: a step-by-step guide

Removing rust: the preliminary step to paint the metal

First and foremost, it's important to remove rust from the metal surface. To remove it, you have the choice between several techniques, either chemical or manual.

Regardless of the technique used, keep in mind that rust often spreads from the edges of an object as well as from solder joints. It will therefore be necessary to pay special attention to these places. If luckily your structure is already rust-free, you can already move on to the next stage of the project! However, if the structure is very rusty, consider separating its various components in order to work more at your ease.

Manual techniques for removing rust

The manual technique involves scrubbing the metal surface with a wire brush or file (manual or electric), emery cloth (sandpaper) or a grinder with a saucer brush. If the weld marks come out, insist on this section until you get a smooth surface.

You could also remove rust with a brass or glass brush. Another handy tip would be to rub the metal with a simple aluminum foil sheet, being sure not to use the shiny side. However, it will take a little more patience to remove all the rust with this technique.

If the metal surface is completely rusted and you need to work quickly, it's possible to heat the surface using a blow torch or heat gun. The heat will cause the paint to blister and it will be much easier to remove it with a wire brush.

Chemical techniques to get rid of rust

As the title mentions, these techniques involve using a chemical liquid to destroy the rust. There are several options available to you regarding the type of product used, although phosphoric acid is an often prioritized choice. You can apply it with a brush or by dipping the object directly into the product if it is small. To avoid burns, protect yourself adequately with gloves, protective goggles and a mask.

For a technique that is a little more accessible and less aggressive, the use of an oven cleaner is of great help in removing rust. Just spray the product on a rag and apply to the rusty surface. Wait about a minute, wipe off and rinse.

A hybrid technique for removing rust

Apart from the previously mentioned techniques, one technique stands out from the others because of its high efficiency. It consists of making a mixture of citric acid and water, in the following proportions: two tablespoons of citric acid for ½ litre of hot water.

Apply this mixture and wait a few minutes. Then brush and dry the surface. Please note, however, that this technique is not recommended for aluminum. For this material, it is recommended to use a trisodium phosphate-based cleaner. The latter is a powerful and biodegradable cleaner, also used for cleaning stoves.

A flawless paint application on your metal surface

Primer: yes or no?

To properly prepare the surface for primer application, always wipe the metal with a damp sponge and dry the surface carefully with a rag. Now is the time to apply an undercoat (primer) to allow the paint to adhere to the surface. As a guideline, a zinc chromate-based rust preventative primer is a good choice. It should be noted that if your surface is aluminum, no primer is required.

Thereby, it should be mentioned that some brands of glycerophthalic paint do not require the application of a primer, so it's essential to check with the manufacturer on that matter. In addition, some types of primer may be incompatible with the paint chosen, so it's important to be vigilant in this regard.

When applying the primer, prioritize using a small round-tipped paintbrush. This will allow you to reach narrow surfaces easily while being able to dose the applied amount to the surface.

Paint application

Now apply the paint of your choice to the metal surface. In order to optimize the adhesion of the paint to the metal, prioritize glycero paint. The latter will penetrate quickly on the support, in addition to being able to effectively hide small imperfections that may remain following the removal of rust.

When purchasing your paint, you will have the choice of a matte, satin or gloss finish. In order to make a thoughtful choice, remember that the higher the gloss level of the paint, the longer the paint will take to dry. Fingerprints will also be more visible on paint with a gloss finish than on one with a matte finish.

In order to minimize the possibility of brushstrokes appearing on the surface of the metal, application with an aerosol or spray gun is strongly suggested.

Some recommendations for painting metal like a professional

At first, avoid painting in intense sunlight. This would cause the paint to dry very quickly, letting the brushstrokes appear on the surface. Ideally, work on warm days (when temperatures are between 15 degrees Celsius and 25 degrees Celsius).

A windy day will also have a detrimental effect on the drying time. In addition, the wind could cause impurities to settle on the fresh paint, which would be very annoying. Working in a context of high humidity is also to be avoided, the ideal rate should be between 35% and 55%. Likewise, avoid painting if it has rained in the last 48 hours or if precipitation is expected within that time.

WOULD YOU LIKE TO HAVE AN IDEA OF THE COST OF YOUR PAINTING PROJECT? Try our price estimator which allows you to calculate according to the dimensions of the parts and the number of colours.