Yes, but the term rust is more commonly associated with the corrosion of carbon steels. Stainless steels can also corrode, some more than others. The higher the chromium content the less likely the stainless steel is to corrode.
The Complete Guide to Painting Stainless Steel
Stainless steels have an aesthetically pleasing appearance, and can be further polished or painted to enhance this feature. Painting may actually reduce the corrosion resistance, but may be required for other reasons such as product marking or identification, or for the protection of carbon steel welded to it.
Surface preparation prior to paint a stainless steel surface is as important as it is for carbon steel. The preparation required will depend on the surface finish of the stainless steel.
How To Prepare Stainless Steel for Painting
Cleaning is usually carried out after welding or fabrication, including removing heat tint from welds. The cleaning required depends on the intended application as well as the coating system to be used. The recommendations of the paint manufacturer should be followed. Also do not use steel wool during preparation as this is typical made of carbon steel which can leave residues causing rusting on the surface of the stainless steel surface.
Cleaning Methods
Pickling
Mill scale on HRA and welding or heat treatment heat tints can be removed by pickling with pickling paste, or by immersion in a mixture of nitric and hydrofluoric acids. Consult Austral Wright Metals for details. Thorough rinsing after pickling is essential.
Blasting
This method of cleaning is particularly useful for large structures and is highly effective in removing mill scale. Blasting media must be clean, free from metallic iron, not previously used on carbon steel and free from chlorides. Suitable blasting media are washed silica sand, stainless steel shot, glass beads. It is advisable to passivate the stainless surface with nitric acid after blasting to remove any possible carbon steel contamination and ensure optimum corrosion resistance.
Other methods of preparing stainless steel for painting
Small areas can be cleaned with a stainless steel wire brush, disc grinder, flap wheel or other abrasive. Use only clean, uncontaminated consumables intended for use on stainless steel.
Degreasing
All fabrications should be degreased to remove the shop soil almost inevitably picked up while being worked.
Water soluble solvent degreasers are most easily used. Consult the paint supplier for details.
Cleanliness can be checked by ensuring that the surface dries water break free.
How To Paint Stainless Steel
The appropriate paint system depends on the application, the surface condition of the steel, and the degree of protection required.
This guide covers generic paint systems. Manufacturers have their own proprietary versions of the systems, and will provide advice.
Cold rolled stainless steel with a 2B or BA finish has a smooth surface profile, and requires a primer coat to ensure good adhesion.
Undercoat and Primer…What are they and why are they so important?
Undercoat and Primer are key components in the Painting process. It is imperative that they are done and must be considered when painting your home.
Whether your painting a small internal or a large external project, understanding how to use Undercoat and Primer will influence the finish of your project dramatically.
Paintway give you a a brief run down on what Undercoat and Primer are and how to use both materials in your next painting project.
A primer or undercoat is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.
Prepcoats prepare the surface to be painted with a topcoat. Primers, on the other hand, adhere to timber surfaces and contain stain inhibiting tannin blockers, while an undercoat is ideal for preparing plasterboard.
Acrylic Primer: used to seal bare areas before painting the finish coats. For example bare plasterboard walls or ceilings.
Oil Primer/Undercoat: used as a binding coat between glossy surfaces such as windows, doors, frames and skirting and your finish coats. Most paint jobs older than 4 years would generally have been painted in enamel paints. For example repainting Enamel surfaces or bare hardwood.
Water based Undercoats: there are a few manufacturers that make a water based undercoat. Its best to talk to them and doing a test sample to check if it sticks. The key to these water based products sticking to enamel, is thorough preparation.
Note: if you want to check if you have enamel surfaces – get some methylated spirits and use a old rag and rub done the area to be tested. If the paint comes off its acrylic – if not its enamel. Be careful not to mistake paint rubbing off with old dirt.
If already have enamel painted surfaces and you have used the appropriate primer or undercoat you now have the option to convert from enamel to water based top-coat. The advantages are they are less smelly (low odour) and easier clean up paint – they are usually referred to as Acrylic Enamel. Not only are they easy to use you can wash up in water.
