"How do I establish my weights? Do I weigh one brand and remain with it
forever?"
If only it were that simple. That will work for recipes written
specifically for that flour.
Problem is the recipe author may not make the same assumptions as the flour
mill. The mill may say 19 cups per 5# bag (4.2 ounces per cup), but the
recipe author may have packed the cup with 5 ounces of flour when they
wrote the recipe. So your best bet is to start with recipes/formulas
written in either weights or percentages. Fortunately, there are lots of
books and internet sites that provide recipes this way.
Also, switch to metric, or look for books that provide both imperial and
metric recipes. Liquids may be listed as ml, cc, or grams, all which are
(for *our* purposes) the same for all liquids (chemists may split hairs
here); and dries are always listed in grams.
HTH
Joe