You’ve booked a carpet clean.

To get ready, you’ve decided to move some of the bigger furniture so you can clean the skirting board behind them and give the place a spring clean.

But, there is a problem – where the furniture was, the carpet has turned blue – or has it?

Yes, your carpet has blue squares that match your furniture exactly.  So how did they get there?

Easy – they always were there.  It’s the rest of the carpet that’s changed.

First a little bit of science.

Carpets are dyed with a mix of colours (remeber mixing paints together in primary school).

Of all the colours used, blue is usually the first to be removed by chemical reactions.

The possible reactions are wide and varied, but ozone fading is one and ultra-violet bleaching is another.

Some early nylon carpets used dyes that simply broke down over time with exposure to ozone and sunlight – both naturally substances.

With the blue component of the carpet colour being the most likely to react, it was the first colour to fade.

Hence, the carpet went from a blue-ish colour to a yellow-ish colour (yellow being more stable than blue).

So why are there blue squares on my carpet?

Easy – the furniture has protected the carpet from the chemical reaction – the ozone or the sunlight, so it stays blue.