The art of snowfoam is its chemistry that is designed to foam and attack dirt.
Its designed to be put onto the paintwork which then agitates by movement down the panel and the fact it eats into the foreign matter on the panel in a soaking action. Once it has attacked the dirt or foreign matter it is then sprayed off, the snowfoam has now done its job.
The next stage is to then wash the panel with a quality shampoo which has a good lubricity, forget bubbles its the silkiness of the shampoo that matters which is why good quality shampoos hardly foams at all. Less friction = less swirls.
To apply a second layer of snowfoam and use with a wash mitt in my eyes is incorrect simply because its not the same product as shampoo it doesnt hold any lubricity properties in any form and if you add shampoo to foam it foams less.
Personally my opinion is that, to snowfoam more than once doesnt benefit the paint work if anything i believe its an extra process that can add swirls as any contact before shampooing can do this, hence snowfoaming in the first place for less contact.
See Snow foam in action.
Incorrect washing really does make a mess of your paint, so this FREE video guide has been put together to help you out. Car Wash vs Jet Wash vs £3 Hand Wash