Updated
Yellowed Or Grimy uPVC Frames
White uPVC that has gone yellow, grey or chalky, and will not come back with ordinary cleaner.
Find a window cleaner
What's happening?
There are two different problems that both look like dirty white frames. The first is surface soiling: traffic film, pollen, cobwebs and organic grime that builds in the profile's textured surface and in every corner, and comes off with the right cleaner and some patience. The second is the uPVC itself changing. Ultraviolet light gradually degrades the surface of white PVC-U, and on south-facing elevations, older profiles and frames that have been painted or attacked with an abrasive, the plastic yellows or goes chalky through the material rather than on it. Testing which one you have is simple, and it decides everything: soiling is a cleaning job, degraded profile is not, and no amount of scrubbing recovers it.
What usually causes it?
- Traffic film and airborne grime settling into the textured surface of the profile
- Cobwebs, pollen and organic film in the frame corners, rebate and behind the gasket
- Ultraviolet degradation yellowing the PVC surface, worst on south and west elevations
- Abrasive pads or cream cleaners burnishing the surface so it holds dirt and dulls
- Solvent damage from white spirit, acetone or a strong wheel cleaner softening the surface
- Old paint or an aftermarket spray coating breaking down and going patchy
- Nicotine, cooking film or heating fumes staining internal frames in kitchens and older properties
Is it dangerous?
No. This is appearance and property value. The one thing to avoid is the DIY solvent route: acetone, cellulose thinners and strong degreasers permanently damage the PVC surface, and the frame then holds dirt worse than before.
Can I fix it myself?
Test first. Clean a small patch thoroughly with warm water and a cleaner made for uPVC, using a soft brush rather than a pad. If that patch comes back white, the whole frame is soiling and a full clean will work. If it stays yellow after the dirt is gone, the profile has degraded and cleaning is not the answer. Never use a scouring pad, a magic sponge, a cream cleaner with grit, a pressure washer close to the gasket, or a solvent — every one of those makes the surface worse permanently.
When should you call a window cleaner?
Call a window cleaner when you want the full profile done properly — corners, rebates, behind the gaskets, drainage slots and the trickle vent covers — or when the frames are above ground level. Also call before buying a specialist uPVC restorer: they will tell you whether the yellowing is dirt or degraded plastic, which is the difference between a clean that works and money spent on one that cannot.
What will the window cleaner actually do?
- Test-clean a small area to establish whether the discolouration is soiling or UV degradation
- Wash the full profile with a uPVC-safe cleaner and soft brushes, including corners and rebates
- Clean behind and inside the gasket line where the dirt that reseeds the frame actually sits
- Clear the drainage slots and trickle vent covers rather than cleaning around them
- Finish the sill, drip bead and any cill end caps so nothing washes back down the frame
- Say plainly when a profile has degraded past cleaning, so restoration or replacement can be priced honestly
Frequently asked questions
We’re happy to answer all your questions.
Sources & References
Need a window cleaner?
Compare local window cleaners on Tradehand — coverage areas, accreditations and phone numbers, no middleman.