[Mortis]

My current car had 35% vlt in the start, 50% later and now no sunfilm. I can definitely feel the difference. Which form of UV are you working with ? UVA UVB or UVC ? AFAIK only uvc Requires quartz glass for better transmission, I don't think UVC is completely cut off by ordinary glass

[boniver]

The previous owner of my car got it fitted with sunfilms in 2004, when he took delivery. Those sunfilms did their duty for 15 long years, and the car was never stopped by the police. However, when my car turned 15 years old in April '19, I decided not to take a chance with the sunfilms and got them removed prior to the physical inspection at the RTO. During the inspection, I saw the inspector reject all the cars that had sunfilms, asking their owners to remove those and appear for the inspection again. Needless to say, my car passed the test without any hiccups.

I used the car for a month after that, sans sunfilms, and I won't be exaggerating when I say that it was nothing less than a living hell for me. Being parked in the sun, the cabin would be extremely hot when I'd get in. After turning on the AC, I'd feel the cool air, but I was always doubtful whether the rear passengers got any air or not. In short, the cabin would take forever to cool if it did at all, the AC system being 15 years old didn't help, and the lack of sunfilms made matters worse.

Therefore, I bit the bullet, and got sunfilms installed today, again. The dealer had two options, one that allowed 35% visibility and another that allowed 50% visibility. Decided to go with the 50% ones, as I was sure even the lazy Kolkata police would sit up and take notice if they saw a car with jet-black tints. The entire process took ~2 hours, and at the end of it I was a happy man. Got into the car, switched on the AC, and when I reached my house after a short 5 min drive, the cabin had become considerably cold!

Time for some pictures:

The car in its previous tinted avatar:



After removing the tints:



Picture taken an hour earlier after getting new tints:



Well, now I have 5 years with these tints before I appear for the inspection again when it's 20 years old. Keeping fingers crossed, hoping I won't have to get them removed earlier.

[Sebring]

3M can prove to you that their films reduce the cabin heat. Just go to any 3M car care and they have this Demo for CR 70 and CR 90. This convinced me to go for these. I'm comfortable inside, with the film on - as earlier the car used to heat up like anything! 3M is a billion dollar Corp, doubt that they would cheat.

Originally Posted by gostel

Visible light bears no heat hence reducing it does not actually reduce heat.

[rdst_1]

Originally Posted by Sebring

3M can prove to you that their films reduce the cabin heat. Just go to any 3M car care and they have this Demo for CR 70 and CR 90. This convinced me to go for these. I'm comfortable inside, with the film on - as earlier the car used to heat up like anything! 3M is a billion dollar Corp, doubt that they would cheat.

Do they use thermometers to prove it to you or just allow you to go by your feeling.

[Sebring]

Carry your thermometer, they wont stop you. I think the infrared thermometer should be best to test. I went with my feeling. The point, is I have actually installed the product and am seeing its efficacy.

Originally Posted by rdst_1

Do they use thermometers to prove it to you or just allow you to go by your feeling.

[rdst_1]

Originally Posted by Sebring

Carry your thermometer, they wont stop you. I think the infrared thermometer should be best to test. I went with my feeling. The point, is I have actually installed the product and am seeing its efficacy.

A proof requires measurement of at least some parameter. In this case, that parameter would be temperature. You said 3m proves it, hence my deduction, that they would have shown it to you how much temperature inside the car comes down.
As for trusting billion dollar corporations, I guess you haven't read about all the fines VW has to cough up because they were cheating on emissions or how juries are awarding millions of dollars to victims of Glyphosate, another product by another billion dollar corporation Monsansto, who released the product despite knowing that it causes cancer.

[Thad E Ginathom]

I think there is plenty of experience posted here, my own included (previous car) of the efficacy of 3M CR70. It works! It noticeably darkens the glass, but only a little. It is hardly noticeable from the outside.

CR90 I have not experienced, but it is almost clear. 3Ms own claims for heat reduction are modest compared to CR70, but my hunch would be that it would still be noticable.

CR90 would be my choice as my current car has a slight factory tint. I am not applying it for two reasons: the glass has too many small-chip imperfections to invest in expensive film, and, of course, law/police.

[haisaikat]

Originally Posted by boniver

Well, now I have 5 years with these tints before I appear for the inspection again when it's 20 years old. Keeping fingers crossed, hoping I won't have to get them removed earlier.

Thanks for this tip on sun films while verification for fitness. My Getz has 3 more years to cross 15 years and this will need to be kept in mind if it stays with me for that long. Of course there is only films on sides and rear windows that is hardly visible if they stand next to car but if they see at an angle a golden tinge will be visible for the VK 60 Goldust series films of V-Cool, its in 10th year and running strong as ever.

Originally Posted by rdst_1

Do they use thermometers to prove it to you or just allow you to go by your feeling.

I recall around 10 years back while getting V-Cool installed before the court restriction came in. They used to have a classic test in their showroom where a high powered halogen light would be lit in a rack and there are 3 sliding glasses. They used to ask to put your hand at a 6 - 8 inch distance from the light. First comes the clear glass in between and you feel the heat, then comes the glass with ordinary dye based films that reduce heat by blocking visible spectrum of light mostly and you feel that a semi dark film is indeed reducing heat. Finally comes the magic of a almost clear glass with VKool film on it and the moment it is placed in front of the light you almost stop feeling any heat altogether.

These specialty films (V-Cool used metal oxide sandwiched within their films) block less of visible spectrum and more of IR and UV so that you still get heat from the visible spectrum mostly. But another thing is the color of the dash and interior, beige will absorb less heat that darker tones and this adds to the effect of heating up. But do note that films will slow down the heating but things will heat up if your car is not running AC inside / parked outside.

If someone is sitting at front or window side even at the back they will be able to sit more comfortably in direct sun with films on the windows than without them.

Also there is a long term implication, UV burns your dash color badly and films on front windshield will protect that to a large extent.

See one example, here is the dash from my Getz in 2009 just weeks after putting the VKool films.



This is what it looks today after 10 years in 2019, you would be able to understand.

Originally Posted by Thad E Ginathom

my current car has a slight factory tint ..... expensive film, and, of course, law/police.

Sir, great to see you in action in this forum too as much as in Hifi Audio. While I have gained from putting expensive films yet I have also lost something in process. In one storm some heavy stuff fell on my car windscreen breaking it along with tearing the film. The insurance does not cover films as its plastic equivalent for them and its not factory fitted and non electrical, so no way to insure them. I did not want to shell out another 20K INR once again after this. The car now heats up more as front windscreen allows most heat entry but I have decided to move on.

But what you mentioned about tinted glass is probably the way to go. Some companies do offer heat rejection glasses as part of standard offering, if not in base models but definitely in higher models and those are the way to go as insurance will cover it in unfortunate case of an accident even if its glass and 50% will apply unless zero depreciation cover is there and the court ban is on putting things on the glass but not with tinted glass itself even if some tinted glasses sandwich similar material inside them So I would like to look for this option next time definitely.

[boniver]

Originally Posted by haisaikat

Thanks for this tip on sun films while verification for fitness. My Getz has 3 more years to cross 15 years and this will need to be kept in mind if it stays with me for that long. Of course there is only films on sides and rear windows that is hardly visible if they stand next to car but if they see at an angle a golden tinge will be visible for the VK 60 Goldust series films of V-Cool, its in 10th year and running strong as ever.

I had tints only on the sides and the rear too. The RTO inspector didn't check for sunfilm on the front windscreen though. Some people had clear sunfilms on their cars that didn't hinder the visibility at all, but the inspector rolled the windows down a little and checked for the edge of the sunfilm that is usually visible. In short, get all the films removed before the inspection process. Costed me Rs. 300 at the local garage.

I don't know how long I'm going to keep my car (I have no reason for letting it go either), but I know I'll have to peel off these tints in 2024 again. I also know that as soon as the inspection gets over in 2024, I'll get new tints installed again, unless the police becomes strict about the ban by then. I'd suggest you to do the same. Calcutta summers are really harsh, and you'll understand what I'm talking about when you'll have to travel in your car with clear windows.

My tints aren't clear though, and are very much noticeable. Adding a couple of more pictures I took today:





It's a different story on the inside though. Picture taken midway through the tinting process, showing absolutely no difference in visibility between the rear left window with tints, and the rear windscreen without them:



Doesn't hinder visibility on the inside, so no issues while driving

[hondatoyotafan]

Originally Posted by Thad E Ginathom

While surfing the net for film reviews,, I have noticed that sun film (I think they call it "tints" in USA) is restricted in at least some American states. Maybe it is in some other countries too.

In most states of US and Canadian Provinces especially the sun starved ones do allow full tint on the rear side glasses and partial tints in the front. The cops dont bother you as long as your driving visibility is not hampered or they shine too brightly like the silver tints we used to have on some cars before the ban. I stayed in 4 US states and 1 Canadian one and driven through 40+ of them.I always had tints on my cars as the North American summers even in the colder states is unbearable without them especially with most offices having open parking.

It is funny that a hot tropical country like ours has banned them when they were most needed. Below is a reference of sun film laws in North America

https://drivinglaws.aaa.com/tag/glass-window-tinting/

[Sebring]

In the UAE, you can go as dark as you want. Crime is well under control, so they don't resort to such rules. Now, if you look at any bus/medium-heavy vehicles - at least in the South - they're running full tints and thick curtains inside, to boot. Nothing changed there, post Nirbhaya. It's only the car-owning public who are put to great hardships!

Originally Posted by hondatoyotafan

In most states of US and Canadian Provinces especially the sun-starved ones do allow full tint on the rear side glasses and partial tints in the front.

[hondatoyotafan]

Originally Posted by Sebring

In the UAE, you can go as dark as you want. Crime is well under control, so they don't resort to such rules. Now, if you look at any bus/medium-heavy vehicles - at least in the South - they're running full tints and thick curtains inside, to boot. Nothing changed there, post Nirbhaya. It's only the car-owning public who are put to great hardships!

Also in Hyderabad or AP i see Innova's or Fortuners with the Ruling party emblem and a photo of the leader with complete dark tints with no visibility whatsoever. It is only the car owning public that is being troubled.

[ach1lles]

I know this is an older post but I'd just like to address this now.

Originally Posted by gostel

1.) The ordinary untinted glass is inherently opaque to UV, so where is the need for adding any gimmicks for UV?

This is false.
Glass will only reflect UVB. Most of UVA passes through, and it can be harmful.

Originally Posted by gostel

2.) Visible light bears no heat hence reducing it does not actually reduce heat.

False.
Like any part of the EM spectrum, visible light carries energy (which is why you're able to 'see' it), which is turned into heat when absorbed by the interiors and air once it passes through the glass of the car.
Visible light is majority of the source for the greenhouse effect here on earth, and for the car to heat up from inside when in the sun.

Originally Posted by gostel

3.) The infra-red region of sunlight bears heat and the only way to reduce its effect is to reflect it away from the OUTER surface of the glass window. Sun-films are banned and tinting does not reflect infra-red from the outer surface hence it is just a gimmick.

Glass is opaque to IR. Which is why the heat stays inside.
I suggest you read up on the greenhouse effect from a credible source.

Originally Posted by gostel

We see people walking in the hot sun without sun films. They don't use sun films but use caps, hats, face-covers, nettings, etc to reduce the direct radiation falling on their faces.

Yeah, but they're re-radiating that heat to the environment, without progressively heating up themselves. There's no heat-trap.

[gostel]

Originally Posted by ach1lles

I know this is an older post but I'd just like to address this now.

Thanks for your emotional outburst. Agreed about UVA and UVB, but please don't get emotionally disturbed about reflecting heat to the environment and about visible part of the EM spectrum. The electromagnetic energy spectrum goes from the very long wavelengths to the very short wavelengths. The heat is borne by the infra-red waves and not by the visible spectrum that extends from red to violet. You could stand before a bright LED light and you shall feel no heat impinging upon your face. You could also use a bolometer to measure the heat content of a purely visible spectrum and compare it with heat from an IR source. If you visit a Bawa bakery, you will find the smart Bawa stringing up our old incandescent lamps in series such that the lamps show a faint glow but it feels very hot inside the glass cabinet. The Bawa wants to keep the baked products warm, not lighted.

The sun-film is attached to the cabin-side of the glass, therefore, the heat from the sun has already entered your car. Now, if the film does not reflect the IR back out then it is useless in reducing the heating of your car because the heat energy has already entered your car. If the film does not transmit the IR but absorbs it then the radiated heat will not directly fall on your face but will dissipate in the inside of the car. People have argued that a multi-million dollar company could not cheat. I don't want to debate on that point but I must confess that I am amused. Let the company demonstrate to me that their film actually "reflects" back the IR radiation. Only then will I be convinced that the film is worth its price. For that, the company will have to set up an experiment consisting of collimators, an IR source, and a bolometer with a readout.
Thanks for reading my response.

[haisaikat]

Originally Posted by gostel

The heat is borne by the infra-red waves and not by the visible spectrum that extends from red to violet. You could stand before a bright LED light and you shall feel no heat impinging upon your face.

All spectrum of light carries heat including the visible spectrum. It is not a good idea to compare LED with sunlight as the intensity of the later is way more and makes you realise heat content instantly. As a comparison it is said that 8 hours of LED bulb light contains heat as much as 1 minute of sun exposure if only visible spectrum were to be considered. Hence the difference. If you could find a car with projector head lamps that concentrates the beam with lenses, put your hand in front of it and at 1 feet away your hand will feel more heat. So visible spectrum does carry heat.

With reference to link http://fosg.in/light-and-heat-management/ the solar spectrum is divided in to three bands i.e.

Ultra-violet (UV) – 290 nm – 380 nm
Visible light – 380 nm – 790 nm
Infra Red – 790 nm – 2500 nm

The energy distribution within the solar spectrum is UV = 2%

Visible Light = 47%
Infra red = 51%

So I agree to your POV where you say many manufacturers report the IR part incorrectly and purposefully in misleading ways. But I have found vkool report additionally how much energy is transmitted and how much is reflected and how much is absorbed.

Yes, I did not have a scientific gear to measure them but if you have one I can let you measure in my car. If there is a good product out there I am okay to fall for it sometimes going by trusted hearsay even if I cannot verify it.

It works the same way for TBHP reviews too, if they say a car is fun to drive and responsive we go for it considering the experiences of the people doing the reviews, we do not ask from them a live polygraph test hooked to their brains that indicate how much jump was observed in neural activities that indicate pleasure.

Yes, probably a dual pane window in cars would have been way better.

Attaching one spec sheet for vk70 for reference
VK70.pdf