Should I Get My Car Windows Tinted | The Top 10 Tips | Auto Expert John Cadogan

Time for a quick Jihad on bullshit: the top 10 things you need to know about window tinting Good idea or not? That’s next

Warning: This segment is rated ‘S’ for ‘science’ and ‘T’ for ‘thermodynamics’ I'm very sorry about that Occupational hazard I’m John Cadogan from AutoExpertcom

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In ‘Straya That's what I do Lots of people ask me about window tinting – last week, I got this: “Is aftermarket tinting of any value? Our whole family is fair skinned I believe the standard side windows are by default SPF 46 or 48 and custom darkest legal tint only improves that to SPF 50 Are these figures correct and if so what is the value of this accessory?” So – for those of you unfamiliar with ‘Straya: We love football, meat pies, kangaroos and … melanoma, sadly

And that last one is a real problem, driving along mid-summer in our sunburned country in our shiny new … ultraviolet ovens There are actually three flavours of UV light UVC, which never really makes it to the Earth’s surface – so, not really a factor UVB, which is what causes sunburn – but is not that prolific And UVA – the big one – 30 to 50 times more prevalent than UVB

Penetrates the skin more deeply And then has prison shower sex with your DNA, unpredictably UVA is what you bombard yourself with if you’re moronic enough to lie in a solarium There’s no case to be prosecuted that exposure to any of the flavours of UV is a good idea Especially if by ‘you’ it means you parking your caucasian/Celtic DNA in our sunburned shithole this summer

While we're talking flavours: There are two flavours of automotive glass – laminated and tempered Laminated glass is used for windscreens Where glass is the bread, and a layer of polycarbonate is the filling Happily enough, laminated glass blocks almost all UVA and UVB radiation The second flavour: Tempered glass – like the windows and the rear screen on most cars

It’s just normal glass that’s been heat treated That toughens it up and introduces high residual internal stresses so that when it breaks it does not form long shards that slice and dice you in a crash That's bad Sadly, tempered glass really only blocks almost all UVB radiation (the sunburn one) Unfortunately, tempered glass blocks only about 20 per cent of DNA-damaging UVA (that's the prolific one) In other words – it allows 80 per cent of UVAmore or less straight through And that’s just a rough guide – the actual amount transmitted depends on the composition of the glass and the thickness – it’s not like there’s a mandatory standard for UV transmission and automotive glass So – you’re definitely better off driving with the air conditioning on, and the windows up

But if you are driving along and the sun is streaming through the side glass, you probably won’t get sunburn but you are still being bombarded with about 80 per cent of ambient UVA So that’s hardly ideal Does it not therefore suck the big one that most sunroofs are tempered glass, and not laminated? I mean, if the world were perfect, I’d take laminated, and banish both UVA and UVB Unfortunately, that’s not a choice available to even the scientifically literate contemporary new car buyer And I hate that

Credible branded tint films – from a business you could conceivably believe, like (say) 3M – make claims about UV protection 3M says each of three of its automotive tint films (quote) “blocks up to 99 per cent of harmful UV rays” and for the other one it’s “up to 999 per cent” So that sounds pretty good Unfortunately though, I don’t know what “up to 99 per cent” actually means

Last time I looked, it meant “less than or equal to 99 per cent” – which is hardly reassuring I don’t know what “harmful UV rays” are, either Because, according to the Cancer Council, they’re all harmful I don’t know if this 3M “up to 99-whatever” business is just lawyers and their weasel-word bullshit, and/or generalised marketing department arse-covering and/or illiteracy But it hardly inspires complete confidence in the product

If you were to take these 3M claims in the most favourable inferential light possible, there is absolutely a case for window tinting if it could be guaranteed as a means of blocking all of that UVA that the side glass is so absolutely good at letting through to ravage your DNA According to the Cancer Council: “Clear or tinted films can reduce the amount of UV radiation penetrating through the side glass by over 99%” According to 3M, one of its four automotive tint films are (quote): “SPF of over 1000” but two are only (quote): “SPF of up to 1000” – damn those legal and/or marketing bullshitters to the pit of hell And the remaining one enjoys no SPF designation on 3M’s website 3M also says those three products that do enjoy SPF claims are Skin Cancer Foundation recommended products The scientifically illiterate are pretty good at conflating visible light, heat and UV – but they’re actually from different parts of the spectrum

So it’s worth noting that even a film that looks ostensibly clear – like the 3M Crystalline one – can allow 90 per cent transmission of visible light and still do the mad “up to 999 per cent” UV-blocking voodoo It’s also worth noting that while dark films are perhaps a bonus in the daytime, they might be a safety compromise at night Which is why there are regulations Here in ‘Straya, there are only regulations for visible light on window tint films, not UV

It’s called ‘Visible Light Transmission’ or VLT The minimum VLT is 35 per cent In other words, tint films are not allowed to block more than 65 per cent of the visible light No tinting is allowed on windscreens – not even a clear film – except in a strip up the top In the Northern Territory 16 per cent VLT is allowed on windows behind the driver (so – second seating row and back from there)

In WA and Queensland it’s 20 per cent If you breach the VLT specs in your state, and get pinged, the car is rendered unroadworthy, and then – in the immortal words of Gunnery Sergeant Hartman – you’ll be in a world of shit I really don’t think there’s that much of a safety component to tinting Dark films might reduce side vision a little bit at night, but might also reduce fatigue during the day In a crash where the side or rear glass gets shattered it might mean there’s fewer hail-sized residual stress relieved glass particles being shot around inside thanks to inertia

The film might bind them together Just like The Force Right about now we’re on the cusp of another six months of summery hell, here in ‘Straya So a key question among car buyers is: Will tinting make my car any cooler? And the clear answer is: Not really Tint film manufacturers – knock me down with a feather – make all manner of bullshit claims about cooling

Here’s one 3M prepared earlier “rejects up to 97% of the sun's IR rays and rejects up to 60% of the heat coming through your windows

” – 3M This is one of those bullshit claims that’s probably true – it’s just self-promoting and meaningless Inconsequential is probably the best word for it There are two main modes of heat transfer to and from your car – radiation and convection Radiation is from the sun streaming through the vacuum of space – those photons – for 500 seconds, or something, and then belting into your car and turning it into an oven And convection is the main mechanism for heat loss from or cooling from the hot car – essentially bleeding heat off into the surrounding air

That’s just how this works Heat transfer for dummies Eventually you get to a point of temperature stabilization – you might call it heat soaking, where heat loss to convection equals heat load from radiation (And I’m simplifying this just a bit, because the car also rejects heat by radiating) Anyway – the thermometer is stable, ultimately, in respect of the air temperature inside the car

Thought experiment time Summer Hottest part of the day The main radiant heat load is hitting the roof, not the windows Therefore, the windows are not a contributing factor in a major way to radiant heat load

They’re just not Therefore, tinting can’t help much, even if it does block radiant heat Tinting is also an additional layer of thermal insulation over the windows – and this will hinder convective heat loss Marketers – such bullshitters – the up until now undiscovered fourth law of thermodynamics If tinting actually made your car cooler, 3M and its competitors would be doing umpteen tests that demonstrate this everywhere from here to Dubai and Egypt

If you want your car to be cooler in summer – just park under a tree The leaves absorb solar radiation to photosynthesize Or fit a small adhesive solar panel and run a fan that draws ambient air into the car to improve convective heat loss from within Far more effective If you decide to go ahead with getting your car tinted you want someone credible doing the job of applying the film Make sure they give you a guarantee, and make sure they’re likely to be in business still, in three to five years – in case you need to make a warranty claim

Make sure they don’t exceed the VLT limitations in your state Make sure they use a credible film from a reputable manufacturer – not some cheap Chinese knock-off crap that looks suitably dark but which you have no way of knowing whether or not it actually blocks any UV radiation That’s kind of important Commercially, one of the ways a tinter can pump up his profit is using the lowest cost tint film The input materials, right? You definitely don’t want that

Finally, my number one tip is: Do not get the dealership to tint the windows for you They get the same tint guy you could get to do the job He’ll drive in, in his van and he’ll do it before you collect the car It'll be a convenient exercise It’s the same tint, done by the same guy – guaranteed

The only difference is: The dealership will screw him down on the price, and mark up that same price up for you – by the traditional dealership parts and accessories margin of one billion per cent On special – this month only (perhaps): We’ve slashed our margin on tinting down to just 500 million per cent That's 50 per cent off Don’t miss out (That statement brought to you by honestadvertising

com) The dealership will of course dangle the carrot of wrapping this over-the-top tinting cost in the finance – so you can generate even higher commissions for the dealership there, and pay even more, ultimately, for the tinting Lucky you In conclusion:Automotive glass does a decent – but not exemplary – job of blocking some UV Unfortunately it does allow quite a lot of damaging UVA straight through

Tinting – with the right film – is certainly a hedge against that The dark stuff for the rear glass – in the states that allow that – is a decent (but imperfect) hedge against prying eyes, too And it could help in a very minor way in a crash But blocking that UVA is the main rational reason for getting your windows tinted Up to you

I’m John Cadogan – thanks for watching

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