Calculating final tint after tinting over factory tint

[HardyHarHar]

Hello,

My vehicle has factory tint on all but the two front side windows that I believe is 25% from the factory.

I wanted 12.5% so I added a tint film of 50% hoping for a final ting of 12.5%

My math was .25 x .50 = .125 or 12.5 percent (or so I thought)

 

The finished job BARELY looked any different from the factory tint.  It was maybe just a barely noticeable difference but I was expecting a much bigger difference.

To my eye, it looked like it went from 25% to maybe 24 or 23%

What I wanted was for it to be a bit difficult to see through.  Not quite Limo dark, but just one step up maybe.  Where did I go wrong?

 

Thanks

Edited June 19, 2018 by HardyHarHar

[Bham]

I don’t know the math for Tint on top Tint    

But look at it this way.  50% film is 50% darker than clear glass.  This is why you did not notice a difference.  The lower the percentage the darker the film.  70% film would be 20% lighter than the 50%.  30% film would be 20% darker than the 50%.  So on and so forth.  

 

To achieve a 12.5% by adding to a 25% existing shade, you would need to add at least a 30% film, if not a 25%.  

[highplains]

21 minutes ago, HardyHarHar said:

 Where did I go wrong?

There are a number of different variables. What was the actual (meter verified) vlt of the glass to start? What was the actual vlt of the film(I've seen the actual vlt of "50%" film be anywhere from 48-58%) added? Did you also tint the front two windows? What color is the interior? You may very well be at your desired 12-14% but with a light interior and/or untinted front windows it wont make much of a difference. I've seen Tahoes/Yukons with factory privacy glass that meters 20% butted up against 10-12% and the untrained eye would never notice the difference. 

 

Edited to add that rarely does "meter math" prove to be perfectly accurate in practice.

Edited June 19, 2018 by highplains

[Ryker]

Going from 25 to 12 percent is barley noticeable to the human eye.   You need to do more like 20% over factory to really be able to "see" a difference!

[Naples Tint Company]

I use my tint meter and a small sample to check and adjust accordingly. I can usually nail it down in the 11-14% range with the right pick but usually it’s 38 or 32 on top of a light factory tint. 

Edited June 20, 2018 by Naples Tint Company

[HardyHarHar]

Thanks for the advice.

I re-ordered.

This time 30%

That should do the trick.

I pulled all the 50% back off before it dried.

[Super Dave]

1 hour ago, HardyHarHar said:

Thanks for the advice.

I re-ordered.

This time 30%

That should do the trick.

I pulled all the 50% back off before it dried.

If you want it to be a little difficult to see inside, you should probably go ahead and order a 20% down to even a 15%. Hard to say for sure, without knowing the vehicle. I put 30% on top of factory tint for the dealership every day. You can see right through it.  I wouldn’t get too hung up on the actual % reading, the same % can look completely different on 2 different cars. In most cases, trucks and SUV’s need a little darker % on the back to achieve the privacy your after.

[quality tintz]

20 percent or 15 over  factory!!!

[HardyHarHar]

Thanks,

I know it won't be Limo dark but that's ok.

I decided 30% laid over factory would probably be the best compromise.

Did some more thinking and going too dark might make it a bit difficult to see out at night, for me anyway

I guess it's not that easy to see inside now except in the brightest sun light because the fronts are 20% so the 30% over factory in the back should do.

Plus the possibility of attracting LEO the darker it gets.

 

No big deal to change it later if I want to.

[ErieTint]

7 hours ago, HardyHarHar said:

Thanks,

I know it won't be Limo dark but that's ok.

I decided 30% laid over factory would probably be the best compromise.

Did some more thinking and going too dark might make it a bit difficult to see out at night, for me anyway

I guess it's not that easy to see inside now except in the brightest sun light because the fronts are 20% so the 30% over factory in the back should do.

Plus the possibility of attracting LEO the darker it gets.

 

No big deal to change it later if I want to.

 

I currently have 35% over my factory windows on my 2006 GMC Sierra. They meter to either 7 or 8 on my Enforcer II.

 

My most common request when going over factory has been 15%. I have had a small handful ask for 5% over their factory tinted windows. 

 

If you are just looking for a little extra and to still be a touch darker than the fronts you should be just fine adding the 30% over top.