Pinking in uPVC windows

Pinking in uPVC is a pink or brownish discolouration that can appear on parts of white window frames. It is rare. I can’t point you to a published explanation of it, so this page is my experience from the trade, with the limits said plainly.

What pinking in uPVC looks like

If your frames pink, the frame itself is at fault, because no amount of scrubbing helps. Usually only some parts are affected. The openers might go pinkish-brown against a frame that has kept its white.

It isn’t confined to the frame. Trims and bay poles can do it too. I once photographed a plastic Georgian bar between the panes that had discoloured over about a decade. I replaced the sealed units, and used a white powder-coated aluminium bar instead, which doesn’t suffer from it.

Why pinking happens in uPVC frames

I am only giving you my opinion, because I haven’t found a published account that settles this. I believe it is a bad batch of material, not a general weakness in uPVC. A few things in my experience point that way:

• It affects some parts and not others on the same window.
• It seems to show up more on north-facing frames. Bright sun appears to bleach the colour back, so south-facing frames recover.
• I was told of one profile maker that had a problem in the second half of the 1990s. I won’t name them. Several of their trade customers were caught between an unhappy homeowner and a supplier at fault.

I was told that the cause was how a pigment, titanium dioxide, reacted with the stabiliser in the mix. That came to me second-hand and I haven’t been able to check it, so take it as a theory.

Is it recycled plastic?

Probably not, and be wary of the claim. Some salespeople say their frames contain “only virgin material”, unlike a rival’s. In my opinion that is a sales line to scare you into one brand. Any maker could have a bad mix. For how that pitch works, see our guide to the double glazing salesman.

What to do about pinking uPVC frames

1. Photograph the frames and note which sides of the house they face.
2. Find your guarantee and the installer’s details, and contact the installer in writing.
3. If the installer has gone, check whether an insurance-backed guarantee covers it. Our guide to buyer beware explains how that works.
4. Ask what is proposed. One fix I have heard of is spraying the frames on site. That is a coating process designed for a factory, so ask for the finish, the guarantee on it and how it will look.
5. If the supplier does nothing, a specialist coating is an option. Ask for a written guarantee and get the cost itemised.

Door panels that go off colour

Many people asking “does uPVC fade” have really seen a door panel that has gone off colour. That is a separate problem, and the history is old.

The earliest feature panels in uPVC doors were glass-reinforced plastic. They yellowed, and were dropped, but plenty of people saw them. The next kind was vacuum-formed uPVC sheet glued to a foam core, and the early ones also faded. In my experience heating them to form the shape damaged their resistance to sunlight. Panels made now rarely have the problem. I haven’t got a published source for this history, so treat it as what I saw.

What to ask about pinking before you buy

1. Which profile is it, and who makes it? Profiles for white frames are covered by BS EN 12608-1, the standard for light-coloured profiles, so ask whether theirs are made to it.
2. What is the guarantee on colour, and how long does it last?
3. Is the guarantee insurance-backed?
4. What would you do if the frames discoloured?

Our guide to wood grain effect uPVC covers coloured and foiled frames, and our quote checker shows whether a quote is in line. See windows explained for more.