I have been bubblewashing for three years now, and am intrigued by this different approach, especially the potential to use no water (we are in a decade-long drought), and less handling. Magnesol is a proprietary formulation of magnesium silicate that is purported to remove water, soap, and FFAs through adsorption and removal via filtration. One must first recover methanol to use this process. The commercial product adds about 10 cents/gallon, but regular talc may be less expensive. Any thoughts?

Ordinary talc is crystalline so doesnt work nearly as well as magnesol which is amorphous and porous. Magnesol is what is known as 'synthetic magnesium silicate' to distinguish it from talc. However, there are chinese versions of magnesol which are much cheaper eg http://www.chem-world.com/magnesium-silicate.htm
but the down side is you seem to need to buy these in large quantities.