Okay, so what about Corn Starch?
I've never seen corn starch used on any type of paint nor have I ever used corn starch on any type of paint.
I've heard that in the old days, that would probably be from the 1960's and older, that some people would rub paint down with corn starch and the corn starch acted to fill in the swirls. At least this is the jist of what it was used for as I've read about the topic over the years.
From experience working on both single stage paints and clear coat paints I certainly would never try anything like this on a clear coat finish.
Also from experience, whenever I find someone using some seemingly wacky product or method to do something it's almost always because the person doesn't know there actually exists a specific product for the process they're trying to do.
That kind thing happens too when people start mixing chemicals to try to create the exact product they need, the problem isn't the product doesn't already exist, it's just they don't know about it.
Here's another old practice, throwing a bucket of ice water, that is ice and water mixed together, over a freshly waxed car. Again I've never done this but from what I've read the purpose was to speed up the hardening of the wax on a warm day. The cold water would would cool the surface down and cause the sheet metal and thus everything on it, (paint and wax in this case), to contract. The wax would harden, and at some level be trapped better into the paint at the microscopic level.
While I've never done the above I could see how this would work on a warm or hot day. I'm not sure why there would be a hurry to cool the surface down as that would take place, in most cases, during the night. As the temperature drops, the wax would that was warm and more liquid would become more firm. There's also the time factor and the wax would continue to dry as time went by, that is any carrying agents would completely flash-off or evaporate.
I'm of the school of,
KISS = Keep it Simple Simon
Don't make things any more complicated than they have to be which sometimes seems to be the opposite trend for extremely AR online enthusiasts.
:laughing: