Preparation for different substrates.

A wise man once said that there is no such thing as trying: you just do, or you don’t. That is exactly true of doing the correct preparation before painting for coating a surface. The prep work can be different depending on the substrate, so you must make sure you’re following the correct guidelines to give yourself the best results.

Bare Metal

The first thing that you need to do when preparing bare metal is to make sure that there is no debris or contamination on the surface. You can do this with a special cleaner or by applying Rust-oleum 2901. Then thoroughly rinse the surface.

When you have done this it is vital to leave it to dry before you try and apply the first layer of paint.

There are some paints that can be used directly onto bare metal without the need or a primer. Hard Hats and Combicolor both fit the bill in that sense. However for longer lasting, high quality results a primer is always recommended.

Vitally, you must first remove any loose rust with a scraper. Once the larger bits are off, then the surface needs to be sanded to remove some of the fixed rust and to provide a nice smooth surface to then paint on. Once this has been done then the process is much the same as with Bare Metal, but I would recommend using a rust prevention product such as 2169/2182 to prevent further issues with rusting. However this step is not essential as most Rust-oleum products already come with some level of rust prevention technology built within them.

Galvanised Steel

Galvanised surfaces are essential to proper preparation. They tend to get a build up of Zinc Oxide on the surface, which is fairly alkaline and can cause issues when painting onto it, so it is important to remove that first. So the first step is to use light sandpaper and water, and then use a product such as Surfa-Etch 108 to neutralise any alkaline residue and give better adhesion to the surface. The next step is to apply an adhesion primer before top coating. It is not recommended to apply 2 in 1 topcoats directly onto Galvanised Steel: the temperamental nature of the surface means that an adhesion primer will generate far better results.

Aluminium

Aluminium is very similar to Galvanised steel in that it gets a build up of Aluminium Oxide on the surface. This needs to be removed with light sandpaper and water. this will also roughen up the surface, allowing for better adhesion. But not matter how good your preparation of Aluminium is, you should always use an adhesion primer. An adhesion primer is always recommended over an ordinary primer or a 2 in 1 primer and topcoat system, as aluminium needs the extra help with adhesion.

 

 

Bare Wood

The most important thing when preparing wood is to ensure that the wood is completely dry. If it isn’t then the paint will get damaged from the underneath and you will have to start all over again.

The first step is to clean and sand the surface. Not only will this allow for better adhesion when you come to painting it, but it will also smooth out any unwanted bumps in the wood. Then you just ensure that all of the dust from the sanding is cleaned away before you apply the first layer of paint.

Plastics

As you probably already know, only hard plastic surfaces – such as PVC – can be painted.

Cleaning and degreasing the surfaces prior to painting is essential, as a lot of grease and oil can build up on plastics. Then, once you are satisfied that it is clean you will need to sand it down to roughen the surface and allow for better adhesion. To ensure that everything is clean after this it will need to be cleaned and degreased again, before applying an adhesion primer. As I have mentioned previously, 2102 and 3302 are very good for this. If you do not want to use a primer then a product such as Combicolor Multi-Surface can be applied directly to plastics, providing the other stages are completed properly.

Concrete

For the first 30 days, concrete cannot be painted. If you try to paint it before 30 days has passed then the paint will flake off. To check whether the concrete is ready to be painted, tape a plastic sheet to it (1mx1m) and leave it for 24 hours. If there is any moisture on the sheet, discolouration or condensation on the concrete afterwards then it is not ready to paint yet.

Then you need to clean the surface with a cleaner such as 2901. Smooth concrete will also need Surfa-etch 108 for added adhesion.

 

Correct Preparation makes the job a lot easier.