19th Aug 2021

When painting non-wooden surfaces, preparation is of paramount importance and this differs dependent upon the type, porosity and surface finish.
Painting on non wooden surfaces

Metal surfaces

Treating metal before it is painted will ensure a clean, crisp finish, and this is particularly important if the surface is exposed to the elements. Ferrous and non-ferrous metals react differently to climate conditions so preparation will vary. For ferrous metals, all rust must be removed using a wire brush and a rust inhibitor applied. This will stop flash rusting appearing on the newly painted surface. If the metal is exposed to the elements, a red oxide primer should be used to inhibit further corrosion. Once thoroughly prepped and treated, a standard exterior paint will produce an excellent finish (although there are spray on products available).

Non-ferrous metals tend to be less reactive but it is still essential to have a clean, corrosion-free surface before priming and top coating.

Plastic surfaces

Plastics are non-porous and often have a shiny finish, which create a problem with paint adhesion. Prepare the surface by cleaning with a mineral based cleaner and lightly sand to remove the shiny surface and establish a key for the paint. Do not over sand as this will scratch the surface and show through the finished job. Paint with the correct primer followed by the relevant top coat, for water based systems use a synthetic polyester brush.

If possible it is recommended to roll and if the finish requires ‘Lay off’ with a brush (try our Prestige Synthetic Laying Off brush)

Concrete surfaces

As always, the surface of concrete must be thoroughly cleaned and free of dust. Once clean, it is advisable to use a concrete etching product to ensure an even and sealed surface that is suitable to receive the paint. An elastomeric paint is the best paint for the task as it is flexible, thicker than regular exterior wall painting solutions and will last considerably longer. As a general rule, two coats of paint applied with a medium pile roller will suffice and give a smooth, resilient surface.

High Abrasive resistant paints are available for walkways and other areas where slippage is an issue. These are usually 2 pack systems (polyester or epoxy resin based. A freshly concreted area requires a minimum of twelve weeks to cure before a coating is applied.

Fresh plaster

As a general rule, new plaster should not be painted for 3-4 weeks as it needs to dry, however, this is not always an option, so there are products available that can reduce this time dramatically. Microporous paints can be applied to new plaster as they allow the wall to breathe and dry more naturally. These are Contract matt paints, do not use a vinyl or this will trap moisture leading to future problems with the finish.

It is still advisable to apply at least one mist coat(thin down by up to 40%) to satisfy absorbency of the substrate.

As can be seen, each surface requires a different approach to producing a quality finish. There are many different products available that can create a multitude of effects, but the key to success with all these surfaces is preparation.

Fail to prepare, prepare to fail!

You can see more of our guides in the Knowledge Room, or 

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