Thank you for the measured response. Specs within the film industry are not regulated, so there is some debate as to actual validity of what some manufacturers are claiming. There is marketing gamesmanship to be considered as well. TSER rejection is commonly used to cross compare, but IR rejection has become an important up-sell tool in many instance and you will hear some speak to this (IR light) being what you 'really feel' as heat. True a point, which is why some shops have demo panels with IR bulbs shining through graduated tinted glass panels, in order to showcase IR rejection superiority of one film over another.
In truth, there are other factors that come in to play. Here is a quote from another tintdude thread (link below) where and manufacturer's rep summarizes some of the other elements:
"There are many other specs that affect the performance of a window film. You have TSEa, TSEt, TSEr, SHGC, SC, VLR......... All of these factor into the films performance. If this is all that you have to go by I can see why you think that GR is what affects the change in TSER. Films do 1 of 3 things...they either Absorb(TSEa), Reject(TSEr) or Transmit(TSEt) Solar Energy. You are correct in that IR is the sensation from the sun that we feel, but it is not what wholly makes up Solar Energy(Heat). Even in the representation MMM shows above, they are Highlighting TSER, because that is what is the most important spec. If they felt that IR was the most important spec, you can rest assured with a 97% IR rating they would be highlighting that instead of the TSER."
Even understanding all this, we still have industry specmanship used for marketing purposes. Case in point with 3M using a 97% IR number when it is pulling from a small band of the total spectrum vs. Huper Optik that quotes using the IR entire spectrum. 3M used an asterisk to point this out, but the point is usually missed by most casual readers. They make the argument that they're highlighting the only important part of the spectrum - true or not- it still distorts any apples-to-apples number comparisons.
The rejection/absorption/transmission distinctions are interesting as well. Eastman owns FormulaOne and it has been said from insiders that their F1 Stratos film is simply CTX with an additional layer of Air Blue sandwiched in-between layers, which does give them measurably better performance numbers, but causes the film to trap more heat on the film surface and in turn transmit it inside the vehicle, which has created some concern with tinters that this will prematurely cause the glue layer to fail down the road. You will also hear people discussing performance differences once the vehicle is moving and dissipating absorbed heat vs. a stationary vehicle.
All interesting for those of us fascinated with such things, but at the end of the day, there remains little reason (other than cost) to chose a dyed film when the technology has advanced to where it has, given that the price premium is not substantially greater; especially when amortized over the length of ownership. Dyed film will fade or turn purple over time, with that effect hastened in sunnier locations; it's usually only a matter of 'when'.
Film clarity is important to me, but I can understand that a value buyer may be willing to accept that as an offset for a smaller cash outlay. Thinner scratch layers may likewise be less of a concern if the price is right for some, but a more robust film may be something others would be willing to pay for, if they were aware of this upfront. There is no single best choice for all situations and budgets. If you can educate yourself to know what options matter to you and where spending more makes sense, then you are way ahead of the average person getting their windows tinted.
Link to mentioned thread:
Quoting Film Specs