Why do Plastic Colours Fade?
Have you ever seen a Royal Mail delivery van that’s more than 5 years old, do you own a (once) brightly coloured T shirt that you wear in the garden, or have jazzy curtains in a sunny room? If so, you’ll be familiar with what fun the sun has with primary colours, and how quickly they can fade.
Take clothes for example. Notwithstanding that “faded = trendy” in some quarters, you still need to be careful about what you hang on the washing line all day, as in the before-and-after examples below:
Sunlight attacks dyes and pigments in all sorts of things, but most obviously fabrics, paint and plastics. Being more precise, it’s the Ultra Violet light that does the damage, sunlight being the obvious but not the only source – if you hang around in art galleries and photographic exhibitions like the Tubeway Blogger, you’ll have seen “no flash” notices in a vain attempt to preserve the colours in priceless (and all other) works of art.
Tubeway manufacture in rigid PVC, so let’s get a little more technical.
How does UV affect PVC?
Because PVC uses pigments for adding colour, it is vulnerable to UV light. The extent of this depends on choice of colour, however, as some shades use a lot of pigment whilst others need very little. The ones to watch are those using primary colours, whether on their own or mixed (so red, dark blue and purple are all attacked by UV light). Pigments for these colours are also more likely to be organic, making them easier for light to break down.
Does UV light only affect the colour?
No. Although fading is the most obvious change to a material, there will be other degradation as a result of UV. Plastic will age faster, going brittle over time and discolouring, being most visible in lighter shades.
How can you protect against UV in plastic?
There are a couple of ways to play it safe:
– make sure the plastic you are buying is External or Outdoor grade. This will mean that it includes UV stabilisers which block UV light and slow down the ageing process. Note that sunlight will eventually take its toll on these, but if you consider uPVC double glazing for example, this should last decades without problems.
– choose a neutral colour. Black, white and greys will usually be light on pigmentation, so there is less for the sun to attack. These colours can still degrade, but much more slowly than vibrant ones.
Why isn’t all plastic Outdoor grade?
Again there are two factors:
– UV stabilisers add to the cost of the raw material, so sometimes, buying cheap will be buying a lower grade of plastic.
– certain shades of rigid PVC have the colour affected by the stabilisers. Clear and Frosted shades for example become opaque with these additives.
How will you know what grade of plastic you are buying?
At Tubeway, we list all of the raw material colours we stock, along with their grade and RAL colour. If a manufacturer can’t tell you what grade the material is, it may be Indoor grade or generic regrind from another pre-used source.
Where can you find out more about Tubeway’s colours?
We thought you would never ask!
There is more information on both colouration and what shades we keep in stock at this address:
Can Tubeway make new colours?
Yes. It takes a little time to process, but almost any colour can be formulated, and most can be Outdoor grade. Tubeway will always manufacture to this grade if it possible, and inform you when it isn’t.
If you have any other questions, contact the Tubeway Sales team at [email protected]