Painting around windows sounds simple until you're standing there with a loaded brush and no clear plan. The glass is right there, the frame curves or rebates in awkward ways, and the margin for error is millimetres. Apex Painting handles window frames on projects across Melbourne every week, and the same mistakes come up repeatedly: wrong tape, no tape at all, or cutting in too fast. This guide covers what actually works.
Why window frames need their own approach
Window frames sit at the intersection of two surfaces that move differently. Timber frames expand and contract with temperature and humidity. The glass beside them doesn't. Paint bridging that join without the right preparation will crack and peel within a season, especially on exterior frames facing west or north. Interior frames are more forgiving, but they still need a clean edge and the right finish, because gloss paint on a timber sill shows every flaw.
The frame profile matters too. Flat-section frames are easy. But most Australian homes have frames with a stepped rebate where the glass sits, and that rebate is where paint bleed happens most often. A 1–2 mm overlap onto the glass at the rebate is actually intentional on exterior frames: it seals the glazing putty or bead and stops moisture tracking in behind the glass. Getting that overlap consistent is the skill.
What to tape and what not to tape
Masking tape is not always the answer. On interior work, a steady hand with a quality cutting-in brush is faster and cleaner than taping every pane. Tape on glass can leave residue, especially if it sits in direct sun for more than a couple of hours before you pull it. If you do use tape, use a low-tack painter's tape pressed firmly along the edge, and pull it off while the paint is still wet, not after it dries.
For exterior work, tape is worth the effort on large panes where a slip would mean a lot of glass to scrape. Press the tape edge down with a putty knife or a credit card so there's no gap for paint to bleed under. Don't stretch the tape as you lay it down: stretched tape lifts at the corners and fails exactly where you need it most.
One thing to skip entirely: using old newspaper held against the glass. It shifts, it smudges, and it gives you false confidence while the brush wanders.
Cutting in: technique that holds
Load the brush lightly. A heavy load on a cutting-in brush produces drips at corners and blob marks where the bristles first contact the surface. Wipe the brush on the rim of the tin, then work the bristles into a fine chisel edge against the palm of your hand before you go near the frame.
Start the stroke a centimetre or so from the glass edge, then draw the bristle tip toward the glass as the stroke progresses. This keeps the heaviest paint load away from the join and lets you guide the fine tip into place. Keep your wrist steady and move from the shoulder. Short choppy strokes leave marks.
On the rebate line itself, hold the brush at around 45 degrees to the frame and draw it along in one continuous pass. If the line wobbles, don't immediately go back over it. Let it set for 30 seconds, then correct with a barely loaded brush. Going back too soon just spreads the problem.
Cleaning paint off glass without scratching it
Even with care, paint gets on the glass. Don't panic. Fresh paint comes off with a damp cloth and no fuss. Dried water-based paint lifts cleanly with a plastic scraper or a fresh single-sided razor blade held at a low angle, around 20–30 degrees. Oil-based paint that's fully cured needs a razor blade and a little mineral turpentine on a rag afterward to remove the residue.
Never use the corner of a razor blade. It will scratch. Use the full flat edge, keep it wet (water works for latex, mineral turpentine for oil), and work in one direction rather than back and forth.
On textured or tinted glass, be more careful. A blade can dull a surface coating. In those cases, a plastic scraper and a little methylated spirits are safer.
Exterior window frames: extra considerations
Exterior window frames need more preparation than interior ones. Any existing paint that's flaking, chalking or lifting needs to come back to a stable base before you coat over it. Painting over a failing surface just traps the failure and the new coat peels just as fast. For more detail on spotting failing paint before you start, the article on the early signs of exterior paint failure covers the warning signs worth checking across the whole facade.
Primer matters here. Bare timber on exterior frames needs a quality oil-based or acrylic primer before any topcoat, or the paint will soak in unevenly and dry with a patchy sheen. Spot-prime any areas you've sanded back. Give the primer time to cure before topcoating: read the tin, and if the temperature is above 28°C, add 30 minutes to whatever it says.
On weatherboard homes especially, the window frame and the cladding behind it are often painted in the same operation, but they may need different products. If you're repainting weatherboards as part of a larger project, the technique for repainting weatherboards the right way covers surface prep and product selection for the cladding itself.
Common mistakes worth avoiding
- Painting in full sun. Direct sunlight dries the paint on the brush faster than you can work, leaving drag marks and lap lines. Paint window frames in shade or early morning.
- Skipping the sash detail. On double-hung windows, the sash rails and stiles need to be painted in the right sequence so they don't stick together. Paint the meeting rail first, then the stiles, then move to the frame. Leave sashes slightly open until fully dry.
- Using wall paint on frames. Interior wall paint (flat or low sheen) doesn't hold up on window frames, which get touched, cleaned and exposed to condensation. Use a semi-gloss or gloss in a trim formulation.
Window frames are a detail, but details are where a paint job either looks professional or looks rushed. Taking the extra time to tape correctly, cut in steadily, and scrape the glass cleanly afterward is the difference between a finish that holds for years and one that invites questions at every inspection.