Tint over tint

[Naughtysauce]

New to the forum, but I've been getting tint in my car ever since I could own one.

 

I just bought used 2018 Honda, back already came tinted and I tinted the front w/ XR Plus at 15% and 70% for the windshield(I'm not really impressed w/ the heat/IR rejection but that's another topic) I have a tint meter and the backs read it to be around 25% which is def not dark enough for me, plus it looks a bit silly having the front darker than the backs.

 

I spoke to my normal tint guy and he said that he's done plenty of dual layers as long as the existing tint is in perfect condition which it is. So he agreed that he can do it to save me the $200-300 removal fee, plus he says a double layer will provide better heat protection than a single layer, almost to the level of ceramic. I will test that as I have an IRR meter as well once it's all said and done. The only stipulation is he cannot warranty it and I was fine w/ that as I don't plan on keeping the car more than 2-3 years and I live in a very mild climate in Socal.

 

I'm also considering putting another layer of film over the 15% fronts, I want to get it down to around 10% and the only way to do that is to do a double layer as I could not find an installer w/ 10% in my area, this process is easier since I have a tint meter that we can test different films to see what gets me to the percentage I wanted, I'm thinking either 30-40% will darken it to my liking.

 

My question to anyone that has had double tint done, how long did it last you? Another question that I had is since the fronts are already ceramic, should I put another layer of ceramic or is regular tint just fine? Like I said, I wasn't impressed w/ the heat rejection of the XR plus so maybe putting the 3m ceramic IR over it will get me the heat rejection that I look for. But if its a case of diminished returns by doing double ceramic tint, I'm open to just doing regular tint.

[Guest Todd]

I think you should put three layers of film. Why not?

[About Window Tinting]

Film on film adhesion can be a problem. Gaskets are tight on some vehicles and the additional resistance from the thickness can cause the windows to auto down.  Scratches are more likely. The second layer will more likely peel and therefore why most companies will not warranty the film. 
The most common issue layering film is ‘low angle haze’. 3M Ceramic is a 2Mil film. Add that to an existing film and most likely you will see a haze in the film. 
Safest bet is to remove and apply new film.