Most well known of the Zinnser finishing products are their range of shellac based products. Having lived in the US for a few years I am familiar with their products and I've used several.
Their shellac based finishes range from what we know as knotting-- their sealers, through brown polish to something they call SealCoat. Their range of polishes are formulations of the regular shellac products we are familiar with but with some slightly different names.
Most of their ready to use shellacs have preservatives in them to keep them workable over extended periods, say a year or more. If we mix shellac flakes with one of the forms of alcohol that dissolve the stuff we usually need to use the polish created within a month or so otherwise it won't cure properly. Old mixed/dissolved shellac can be tested by placing a blob on a bit of glass. If it goes hard quickly, it's fine. If it stays soft and rubbery, it's bad.
The Americans use a system of 'cuts' for denoting the strength of shellac polishes. A 2 lb cut denotes proportions of 2 lbs. of shellac flakes per gallon of alcohol. It has to be remembered that the US gallon of water is usually reckoned to weigh eight pounds. If you are aiming for a 2 lb cut in smaller volumes then there are 16 liquid ounces in a US pint, so you add 4 ounces of flakes to one pint of alcohol.
As to your original question regarding a 'wiping' shellac based polish, pretty much all shellacs can be applied with a rag, a brush, sprayed, or built up by french polishing with a rubber. My usual preferred method for large jobs is to get the stuff on fast with a spray gun. It's just a question of scale and time which settles me on a choice of application, although I mostly leave french polishing out of the equation. Slainte.
