What is privacy glass on a car

Increasingly more models in the new car market are including a feature that is known as privacy glass.

It often comes as either one of the highlights of a car’s higher trim level or as purely an optional thing. But just what is privacy glass exactly and what are its benefits?

What privacy glass means and how it is made

Privacy glass is basically the formal term for windows on a car which have been tinted during the manufacturing process. Tinting is usually applied to the rear windows of a car.

While privacy glass usually comes from the factory the car was built in, some motorists may find it possible and opt to install privacy glass on their car via a third-party.

Privacy glass is usually created in an electrical process known as “deep dipping” which involves dyeing the inside of the glass used for a car with a dark pigment.

Family cars and executive models are predominantly the types of cars which have helped to make privacy glass a more common feature in the market in recent years.

When it is available as an optional feature, privacy glass tends to cost somewhere between £200 and £300 to add to a car.

Advantages of privacy glass

Putting privacy glass on cars can bring a few advantages. For one thing, it can filter out sunlight directed at the tinted windows.

Because it is difficult for outsiders to observe who or what is in the rear of a car with privacy glass, the feature can also benefit security. It is not a completely foolproof idea, but you could feel more comfortable about leaving items in the rear seating area or boot of your vehicle if privacy glass is installed to obscure what is in those areas.

On top of these advantages, some motorists may also appreciate having privacy glass from a fashion point too.

Having tinted rear windows can stand out on a car, especially when you compare them to the front windows which will have little to no tinting at all included. There are strict laws which cover how much tinting can be applied to front windows, which is why this luxury is usually reserved for the rear glass of a car.

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IT’S USUALLY in Spring that you start to see window tinting ads appear on TV, online and in newspapers. While it’s possible to purchase window tinting for your home and your car from auto accessories and even hardware stores most people turn to a professional service.

Most professional window tinters would be up to date with the relevant State and Territory laws regarding the allowed ‘darkness’ of window tinting but car owners should also be aware of the laws. Especially, if they’re attempting a DIY window tint.

Like a lot of legislation related to vehicles, the States and Territories are not all equal in what they allow. Here’s what you need to know about window tinting and the law.

Factory Window Tinting

These days, when you look through the brochure of almost any new car you’ll see reference to privacy glass, sometimes it’s standard and sometimes it’s an extra-cost option. Privacy glass at the factory level is a dipped and dyed tint rather than a film-type tint, although the glass can also be dyed at the dealership level. Usually, to stick within the law, privacy glass has a VLT (Visible Light Transmission) of between 15-26%.

This is type of window tinting involves a film being applied to the glass and this can be done by either by a trained professional or a handy DIYer. If you’ve ever covered a school exercise book with ‘contact’ or tried to put a screen cover onto a smartphone you’ll know that if you’re not extra careful when laying the film you’ll end up with bubbles in the surface.

Why tint your windows?

The most common reason people cite for wanting tinted windows is to keep the interior of their car cool and cut down harmful UV and UVB rays. But, according to the Cancer Council of Australia regular automotive glass cuts about 97% of UVB (short-wave ultraviolet light) which is the light that causes sunburn and more than 30% of UVA which is the sunlight that penetrates beyond the surface layer of your skin – it’s prolonged exposure to UVA that can lead to skin cancer. And laminated automotive glass is even more effective at cutting both UVA and UVB, indeed, it’ll cut down around 80% of UVA and it blocks UVB completely.

But what about keeping the interior of the car cool, does window tinting really help? According to a study by the RACQ in 2009 which explored the effects of windscreen sunshades and window tinting on the interior temperature of a car the temperature differences between them are minimal.

What the study revealed was that while clear automotive glass heats up quicker and with a higher interior temperature, but only by a few degrees C, than privacy glass and film-type window tinting, it was also quicker to cool if a shadow was introduced. The tinted windows took longer to reach ambient temperature and had a lower peak temperature than the clear automotive glass with the film-type tint recording a slightly lower peak temperature than the dye-type tint, but the difference was only 2 degrees C; the peak temperatures recorded were 59.7 and 61.8 degrees C, respectively.

What the RACQ study concluded was while tinted windows are slower to heat up than clear glass, the difference is almost so little that it’s almost not worth it. Especially when the fact that the windscreen is not allowed to be tinted and is thus significant entry points for both heat and glare. The study also showed that tinted windows slowed the heat loss from the interior of a car.

What are the rules around window tinting?

In Australia, regardless of where you live, the windows rear of the B-pillar can be tinted as can both the driver’s and passenger’s front window, but the VLT differs with the driver and passenger front windows requiring a greater light transference rate than the rear wiondows.

And, while it’s allowed to fit film-type tinting over the top of privacy glass, the combination of the two tints can’t exceed the allowed VLT (Visible Light Transference) for the State or Territory you live in, which is 35%, 20% or 15%. And aftermarket tinting cannot be applied to the windscreen, although a visor strip is allowed on the windscreen with each State and Territory having guidelines on how big this strip can be, it is generally allowed to cover 10% of the windscreen at the top only and it can usually be any colour. However, all window tinting, be it dye-type or film-type, regardless of where you live in Australia, cannot be more than 10% reflective.

The basic window tinting rules for Australia are (as of June 2018) for rear windows (B-pillar back):

35% VLT – Victoria and Tasmania have the strictest tinting regulations;

20% VLT – NSW, QLD, SA, ACT, WA now allows a darker tint;

15% VLT – Northern Territory allows the darkest tint in the country.

How hot does the interior of your car get?

Your car is, essentially, an unconventional oven. A car parked in the sun can become 20-30 degrees C hotter than the ambient temperature and 75% of that heat build-up occurs in the first five minutes and 90% in the 15 minutes. Leaving the window open (slightly – 1cm) has virtually no impact on reducing the interior temperature of the car.

If you’re a new-car buyer, you will have noticed the back windows are much darker than the front. That’s because cars are coming off the production line with privacy glass. Because of the darkness of the glass, many owners only ask us to tint the front windows, thinking the back ones are already tinted. Unfortunately, that’s not the case. If you want maximum comfort in summer, it’s still a good idea to have all the windows tinted, including the privacy glass, and here’s why.

Privacy glass is made by dying the glass. The dye has minimal heat absorption capabilities and only cuts out a fraction of UVA rays. Privacy glass cuts out light and glare but very little heat. It has similar thermal properties to the clear-glass front windows, which means your car will be really hot when you first get into it in summer, and the air conditioning will use more energy to do its thing. It will also allow harmful UVA rays into the car. So, although many people don’t realise it, tinting these windows still has significant benefits. But what about the darkness of the windows, because privacy glass is often already at the maximum darkness allowable by law (20%)?

Every year, window films are becoming more sophisticated, which means there are more products available for more uses. One such product we recommend for your factory-tinted rear windows is Enersun’s UV Shield film. This film won’t add darkness to the rear windows as it’s fairly light, but it will cut out 30% of heat and 99% of UVA rays. It will also keep the glass from spraying everywhere if the window breaks, which is a great safety feature.

As great as privacy glass looks, and as much as it hides what’s in your car from outside observers, it provides no other benefit and living in such a hot climate, us Aussies need extra protection. So, when we tint your front windows, don’t forget to ask us about tinting the rear privacy glass too. You’ll reap the benefits of a cooler car that is safer and gives the passengers maximum protection from harmful UVA rays. We’re the sole supplier of Enersun window film, all of which is made in the US and is the highest quality on the market, backed by both a Solartint Lifetime Warranty and a manufacturer’s warranty.

So when you’re looking at getting your new car’s windows tinted, call Solartint Caringbah on 02 9525 3766 and ask about films for your privacy glass. We’re always here to help.