The usual surfaces requiring prep for painting will be plaster, drywall/plasterboard, and fibro sheets. These possess similar qualities in regard to preparing for paint. Regardless of whether the surface is a new one, or a repaint, preparation is much the same. Take care if painting on fibro in case the material was created with asbestos.
For new materials, your easiest prep is to first use a sealer or undercoat that will highlight any
If the surface is new it is easiest to apply an undercoat or sealer to the surface as that will make it easier to see any imperfections requiring amending before completion. After this coat, the procedure to follow is the same as a repaint.
If painting over an old coat of paint, it is necessary to ascertain the kind of paint you are over coating (consult our Test Paint Type guide to confirm if further undercoating should be done.) To make sure you are painting onto a surface fit for bonding to the paint, an Adhesion Test is needed. (At the same time, if there are any doubts as to the paints safety, a Lead Paint test is best carried out then, as it is most effective having scored through the surface while doing the adhesion test.) If the surface passes the adhesion test then you can be confident to start doing the preparation work.
Inspect the surfaces for gaps and cracking around frames of doors, windows and any other embellished areas, and pack with an acrylic filler or gapping compound, ensuring that the product you choose is suitable for painting on.
For holes and cracks in the substrate use a filler, which can be purchased as a powder and mixed, or bought made up. For small repairs requiring a single application of fill, use a product that is appropriate for sanding. For bigger holes and cracks, a quicker drying compound should be used, (which will be more difficult to sand), follow it with a coat with a filler that is easily sanded.
All fillers will require a final sand once thoroughly dry, prior to painting. Use fine grade sand paper or fine grade foam sanding block.
Then spot prime/undercoat all areas that have been filled and then you can continue with the painting project.