Contract matt is the no-frills end of the emulsion range — a thin, ultra-flat, highly breathable paint with minimal additives. It's cheap, it covers big areas fast, and crucially it lets fresh plaster keep drying out underneath. That breathability is the whole point: a standard vinyl emulsion can seal moisture into new plaster and end up flaking, whereas contract matt sits open and lets the wall finish curing.
So use it in two main situations. New plaster — thin your first coat down (a mist coat, roughly 70:30 paint to water on bare plaster) to key into the surface, then a couple of full coats of contract matt as your base. New builds and big commercial jobs where you want serviceable white walls fast without spending decorator money. That's exactly where the name comes from — contractors slapping it on new houses.
What it is not is your final decorative finish. Contract matt has no wipeability, marks easily, and the colour range is thin. Once your plaster's fully cured — give it a good few weeks — go over the top with a proper finish coat.
For that topcoat, this is where the supported brands earn their keep. Little Greene Intelligent Matt and Dulux trade emulsions are both fine workhorses over a contract matt base. If you want a flat, chalky designer finish, Farrow & Ball Estate Emulsion in something like Pointing or Slipper Satin gives you that soft depth. For a more durable, wipeable matt that still looks flat, Little Greene Intelligent Matt in French Grey - Pale is hard to beat in a hallway or family room.
One thing to watch: don't try to use contract matt as a budget shortcut on a finished wall expecting it to look like a premium paint. It won't. It's a base layer, not a destination.
Get the plaster fully dry, mist coat with contract matt, two base coats, then your chosen finish. That's the proper sequence and it'll never let you down.