I seriously doubt the Feds care about whether honey is sold by weight or volume. Please post an actual law. Barring that, it's state law that matters. i sell by volume, period. Here is the Texas law for honey sales:
SUBCHAPTER E. LABELING AND SALE OF HONEY
Sec. 131.081. USE OF "HONEY" ON LABEL. A person may not label, sell, or keep, offer, or expose for sale a product identified on its label as "honey," "liquid or extracted honey," "strained honey," or "pure honey" unless the product consists exclusively of pure honey.
Amended by Acts 1983, 68th Leg., p. 1884, ch. 350, Sec. 1, eff. Sept. 1, 1983.
Sec. 131.082. USE OF BEE, HIVE, OR COMB DESIGN. A person may not label, sell, or keep, expose, or offer for sale a product that resembles honey and that has on its label a picture or drawing of a bee, hive, or comb unless the product consists exclusively of pure honey.
Amended by Acts 1983, 68th Leg., p. 1884, ch. 350, Sec. 1, eff. Sept. 1, 1983.
Sec. 131.083. SALE OF IMITATION HONEY. A person may not label, sell, or keep, expose, or offer for sale a product that resembles honey and is identified on its label as "imitation honey."
Amended by Acts 1983, 68th Leg., p. 1884, ch. 350, Sec. 1, eff. Sept. 1, 1983.
Sec. 131.084. SALE OF HONEY MIXTURES. (a) A person may not label, sell, or keep, expose, or offer for sale a product that consists of honey mixed with another ingredient unless:
(1) the product bears a label with a list of ingredients; and
(2) "honey" appears in the list of ingredients in the same size type of print as the other ingredients.
(b) A person may not label, sell, or keep, expose, or offer for sale a product that contains honey mixed with another ingredient and contains in the product name "honey" in a larger size of type or print or in a more prominent position than the other words in the product name.
Amended by Acts 1983, 68th Leg., p. 1884, ch. 350, Sec. 1, eff. Sept. 1, 1983.