For v-j walls and ceilings, doors, trim and windows:
These will be painted in either enamel, or more recently, in acrylics. It is essential that the type of paint is determined before recoating - mixing systems can be a disaster. The simplest test is simply to rub it with some methylated spirits on a rag or paper towel. If you just clean the spot, then it’s probably enamel. If the paint starts to come off on the cloth, then you can bet it is acrylic.

We do not recommend the use of acrylic paints on doors or window frames, as they have a tendency to stick in warm, humid weather. However, overall, it’s best to stick with what is there, unless you’re willing to strip it back to bare timber. Again, preparation is the key - starting with thorough sanding and washing with sugar soap before you start the painting.

Plaster and Gyprock:

Normally inside - and fibro can be treated as plasterboard when it’s used inside - and these days normally painted with acrylic, vinyl or PVA. The best rule of thumb is stay with what you’ve got. For new surfaces, a sealer is essential (according to the Master Painters Association, amongst others) to avoid "gloss banding", that is, shiny stripes along all the gyprock joints and nailing points.