Replacement Windows, Double Glazing, Double Glazed Conservatories and FENSA Information From The Window Man UK

The problem of discolouration of PVC-U does exist but is very rare, and I believe it is caused more by an accident, in an odd bad batch, rather than by deliberately including recycled or 'regrind' plastic in a mix.

If you have windows or doors that suffer 'Pinking' you will readily know that the framework is at fault, and no amount of elbow grease will make it better. Usually only parts of the frame are affected, with some white and some off colour.

There was a particular problem with one well known profile manufacturer in the late half of the 1990's (who I will not name) and a number of it's trade customers are in the 'piggy in the middle' situation of an unhappy home owner and their at fault material supplier. The problem is a difficult one for the blameless window fitting company as the proposal by their supplier is to mask up and spray all the windows on site with a special compound to make them white again. The problem with this solution is two fold: 1. The process (which is used to make coloured windows) is not best suited to outside conditions and is best performed in factory conditions. 2. The window company has the embarrassment of it's 'new' windows being what may look like them being 're-sprayed' for all the world to see, definitely not good for business.

The funny thing about real 'pinking' is that it seems to have nothing to do with ultra violet light stability, because the Sun tends to 'bleach out' the discolouration and in fact the problem shows up worst on the North side where there is less direct sunlight.

So what can you do if you have frames that are pinking then?

Well now you can get out the paintbrush and just DIY repaint them if your supplier is of no help, see PVC-U Colours and finishes, and repainting

Please be aware that the problem of profile being affected by discolouration is nowhere near as widespread as some salespeople make out, and it does not matter who you buy your new windows from, as this could happen if there was a bad mix with a particular type of Titanium Dioxide (Ti02). The main problem has been identified from tests which indicate that it is the the photo activity properties of the Ti02 used. Pinking seems to occur sooner and with higher intensity with high photoactive Ti02, and formulations made with low photo active Ti02 do not show the same signs of pinking. Concerning the other parameters such as fillers, impact modifiers and type of resin, no significant influence on pinking has been identified. Although no effect of the type of lead stabiliser has been established, I rather think that one day all lead and tin based stabilisers will be outlawed by the EC, with calcium zinc based stabilisers the way of the future. Analysis of pinked samples have been carried out by what is called the XPS technique, which stands for X-ray Photoelectron Spectroscopy of surface analysis. In a conclusion, the photo-activity of the Ti02 has been demonstrated to be the main influence in the pinking phenomena, and it is fair to assume that it is the Ti02 interacts with the stabiliser to oxidise it.

I am often asked by prospective customers "Are your windows and doors made from recycled plastic" or "Do your windows and doors contain any recycled plastic". Straight away I know that the likelihood is that some dodgy 'double glazing salesman' has given them the dubious line about how pure their window system is, compared to most of their competitors that go off-colour, which is probably just another sales tactic. See Can I believe the salesperson.

Years ago when a car 'pinked' the ignition was too far retarded, the compression was too high, or cheap petrol was being used, and it was 'pre-ignition', happening when the engine was put on load. I'm showing my age now, and you didn't really want to know all that, did you?

Read a lot more about this on my other related page called Regrind