Since you point me out by name, Ill attempt to explain my unscientific hypothesis on this. I tried this little test about 6 months ago, when I saw another of the many layering debates that Ive read. I believed that carnaubas would certainly build with each layer because I know for a fact that other waxes will build. I really tried to prove to myself that it layered.
Bear with me here....
In Florida, surfing is popular. Any surfer can tell you that waxing your stick is not optional. Waxes like Sex Wax are usually a paraffin base(different wax, I realize) that provides traction on an otherwise slick, wet surface. You dont wax the entire board, just certain areas for grip. This is done by vigorously rubbing the bar across the stick, from rail to rail, in these areas leaving the rest of the stick unwaxed. This wax builds very thick layers with every pass because the wax sticks to itself, leaving a rough grippy surface. The waxed areas are a yellow color and they are up to a half inch thicker than the stick surface. The build is even obvious to an idiot at just a glance. This was the reason that i believed that carnaubas would also build.
We'll just skip the maintanence, etc. of this wax.
Now....
To test carnaubas, I used a Jesse James toolbox painted in black single stage paint and a cheap, lighted magnifying glass from Harbor Freight. Side by side, I applied Sex Wax, PPG and Mothers Carnauba. The Sex Wax built up very fast with each pass, just like on a surfboard. It was an 1/8 inch thick in about 5 minutes. This wax will build on most any clean surface.
Both carnaubas were applied once a day, over 8 days consecutively. This was easy since Im in the garage with this tool box several hours every day Yeah, I know what a waste of time it was but it actually took less time than typing this conclusion. I tried each on 2 different areas for comparison. One area was buffed after each application, the other was not. This should show any build up pretty quickly if the wax wasnt self cleaning. This totals 4 different areas with carnauba.
With every application on both areas, there was no 'noticable' build. The unbuffed areas were cleaned by every reapplication of new wax (it got tough to rub here). After 8 applications of both carnaubas on each area, I applied a single coat of carnauba to a fresh area.
The only slight difference in any of the areas was that the area with 8 buffed coats was a lttle bit shinier. Even looking through a magnifying class, there was really no difference. I even tried scraping each with a credit card. All areas showed an identical amount of very, very fine powder after scraping about a 6" area, that I could only see with the MG.
My personal conclusion:
Even though I cant provide any actual conclusive evidence, Im satisfied from my informal little test that I wasted my time "layering" carnaubas. Im convinced that any sort of nano mil thickness that carnauba may,or may not, gain through layering is absolutely not worth any effort. Any amount of thickness that could be possible after even 8 coats would not make any difference in protection, in the real world, and certainly isnt worth the time and work.
Very unscientific, I know. But it was enough to change my opinion. The time spent repeatedly waxing over wax, is better spent doing something else... or hell, nothing at all.
Applying 2 coats will assure you of better coverage, but thats it. Buffing it over and over will make it shine a little more but probably removes more wax than any gain in shine. If you want that much shine, just get a poly. It lasts longer too.
Hey, its only one opinion. Im sure now I will read some posts on how carnauba layers so well that they now use carnauba instead of surf wax on their stick but at least you know why I no longer "layer" wax.
The car looks unbelievable -- I think I'm going to sleep in it tonight.
