Painting MDF architraves to a professional standard is one of those finishing touches that can make or break a room. Get it right and your door frames look crisp, clean, and factory-finished. Get it wrong and you'll end up with raised grain, brush marks, or paint that peels at the edges. This guide walks you through every step — from preparation to final coat — so you achieve a flawless result every time.
What You'll Need
- Fine-grit sandpaper (120 and 240 grit)
- MDF primer or high-build primer
- Water-based or oil-based topcoat (satin or eggshell recommended)
- Quality synthetic brush (2–2.5 inch)
- Small foam roller (optional, for flat faces)
- Flexible filler and filling knife
- Tack cloth or damp rag
- Painter's tape
Step 1: Fill and Sand the Joints
Before any paint goes on, inspect your mitred corners and any nail holes. Fill with a flexible decorator's filler — not a rigid one, as MDF can move slightly with temperature changes. Once dry, sand flush with 120-grit paper, then finish with 240-grit for a smooth surface.
Step 2: Seal the Edges
The cut edges of MDF are the most absorbent part of the board. Apply a coat of neat MDF primer or a 50/50 mix of PVA and water to all exposed edges before priming the face. Allow to dry fully. This step prevents the dreaded "furry edge" that ruins so many DIY paint jobs.
Step 3: Apply the First Coat of Primer
Apply a full coat of MDF primer to the entire architrave — face, edges, and back if accessible. Work with the grain of the profile, using a brush to get into the curves and recesses. Allow to dry fully (check the manufacturer's drying time — typically 2–4 hours for water-based primers).
Step 4: Sand Back
Once the primer is dry, lightly sand the entire surface with 240-grit paper. This knocks back any raised grain and gives the topcoat something to key into. Wipe down with a tack cloth to remove all dust.
Step 5: Apply the Topcoat
Apply your first topcoat in thin, even strokes. For flat sections, a small foam roller gives a smoother finish than a brush. Use a brush for the profiled sections and edges. Avoid overloading the brush — thin coats dry faster and level better. Allow to dry fully before applying a second coat.
Step 6: Final Sand and Second Coat
Lightly sand with 240-grit between coats, wipe clean, and apply your second topcoat. For a truly professional finish, a third thin coat is worth the extra hour.
Tips for a Factory-Smooth Finish
- Always use water-based products if you want a bright white that stays white — oil-based paints yellow over time.
- Satin or eggshell sheens are more forgiving than full gloss and hide minor imperfections better.
- Paint in a dust-free environment and keep windows closed while the paint is wet.
- If you're painting pre-primed architraves from Univers, you can skip Steps 2 and 3 — just sand lightly and go straight to your topcoat.