MDF is brilliant stuff to paint — dead flat, no grain — and once it's sealed, the job really comes down to two decisions: which finish, and which board.
Prep, briefly. Prime the lot with a solvent-based primer — Zinsser Cover Stain or BIN are the trade go-to — and work primer well into the raw cut edges, sanding back and repeating; they're open fibre and drink paint. Two thin coats, sanded between with 240-grit, builds a glassy base. Keep water-based primers away from raw MDF — they raise the fibres and you'll be sanding forever.
Now the finish — this is where MDF jobs are won. Because primed MDF is so smooth, the sheen does all the talking. For built-ins, shelving and panelling, an eggshell is the sweet spot: forgiving, low-sheen, and it hides minor prep sins. Little Greene Intelligent Eggshell is a cracking choice, tough and self-levelling; Dulux Heritage Eggshell and Farrow & Ball Modern Eggshell also sit beautifully on primed MDF. Step up to a satinwood where the piece takes real punishment — kitchen units, boot rooms, anything that gets scrubbed or knocked daily. Full gloss looks superb but shows every ripple, so save it for flawless prep and a steady hand.
Colour-wise, MDF joinery loves a soft, architectural neutral. Farrow & Ball Pointing and Strong White are lovely off-whites for trim and shelving; Cornforth White gives a gentle warm greige; and if you want shadow-gap drama, Down Pipe on built-in units is a stone-cold classic.
The board matters as much as the paint. Standard MDF hates damp — it swells and never recovers. For bathrooms, kitchens, window boards or anywhere steamy, spec moisture-resistant (MR) board from the start: it's the green-tinted stuff, paints up exactly the same, and won't blow the first time it meets condensation.
Use a foam mini-roller for the faces and a good synthetic brush for edges. Light coats, patient sanding, and you'll get a finish that looks sprayed.