HB 4X4 said:If you use the search feature you would find numerous tint threads discussing these differences. Specifically threads by either myself, or Josh200. I do not have the time to do your research for you.
To give you an easily understandable conclusion.
3M: Either red or green from inside, with a green appearance from outside.
Formula 1: Charcoal in color, both inside and out, excluding when 5% is put over clear glass. Then the green that is seen, is from the glass, not the tint.
I have compared these side by side. I had formula 1 on the front windows, and 3M on the back. I had to do a second layer of tint on the back (formula 1) because the windows appeared green when looking out, and let in a red light which made my interior appear red. (How it let in red light when it looked green, I have yet to figure out. )
Even from higher end 3M dealers, such as Campbell Tinting, it's the same discolored material.
Does the Formula 1 have any brown color to it? I had my old runner tinted (can't remember the brand- Mc something?) and it had a slight brown to it- drove me crazy.